Standard Test Procedure Rhd.bd

Government of the People’s Republic of Bangladesh Ministry of Communications Roads and Highways Department

STANDARD TEST PROCEDURES

MAY 2001

GaziSharif

Digitally signed by GaziSharif DN: CN = GaziSharif, C = BD, O = RHD, OU = NRD Reason: I agree to 'specified' portions of this document Date: 2009.10.23 16:29:59 +06'00'

INSERT THE NEW

FOREWARD

SIGNED BY

FAZLUL HAQUE

STANDARD TEST PROCEDURES (STP) Introduction To enable roads and bridges to be built in accordance with the Roads and Highways Department’s Technical Specifications (Volume 3 of 4 of the Standard Tender Documents), it is necessary for quality control tests to be carried out at both construction sites and regional testing centres. The results of these tests are intended to assist the Engineer in deciding whether or not a particular item of work is satisfactory and to provide a permanent record to show the work has been carried out in accordance with the Contract Specification. To be of use to the field engineer the results of many of the tests detailed must be submitted as soon as possible after completion of the particular item of work, as any work which does not conform with the Contract Specification may be rejected by the Engineer. The Standard Test Procedures detailed in this document are mandatory for the quality control of roads constructed by the Roads and Highways Department. The RHD Technical Specifications when including a test make reference to this document and the tests are referred to by their section number and title, for example, STP 4.3 – Standard Compaction of Soil. Standard Laboratory Test forms have been produced for the tests detailed in this document. Sample calculations are shown using these forms in the relevant sections of the document and copies of the blank forms are available for downloading from the Roads and Highways Department’s Internet Web Site at www.rhdbangladesh.org under the section covering Standard Test Procedures. Alternatively a computer ‘ floppy disc’ containing copies of the forms can be purchased from the Procurement Circle at RHD Sarak Bhaban, Ramna, Dhaka. This manual covers all tests which are needed to be carried out at site or regional laboratories; however, other more specialist or complex tests may be required and these can be carried out at the Bangladesh Road Research Laboratory and in this respect, or other matters concerning these Standard Test Procedures, queries should be referred in the first instance to the Director, Bangladesh Road Research Laboratory, Paikpara, Mirpur, Dhaka.

Roads and Highways Department Bangladesh Road Research Laboratory Table of Contents CHAPTER 1 : DEFINITIONS, SYMBOLS AND UNITS 1.1 1.2 1.3 1.4 1.5

Scope...............................................................................................................1.1 Terminology......................................................................................................1.1 Definitions ........................................................................................................1.1 Greek Alphabet.................................................................................................1.5 Symbols and Units............................................................................................1.6

1.6

Conversion Factors and Useful Data .................................................................1.6

CHAPTER 2 : SAMPLING 2.1. 2.2 2.3

General ............................................................................................................2.1 Sampling of Soils..............................................................................................2.1 Sampling of Bricks............................................................................................2.6

2.4 2.5 2.6 2.7 2.8

Sampling of Aggregates....................................................................................2.9 Sampling of Cement .......................................................................................2.12 Sampling of Concrete .....................................................................................2.13 Sampling of Bitumen.......................................................................................2.16 Sampling of Bituminous Materials ...................................................................2.17

2.9 2.10 2.11

Preparing and Transporting Samples..............................................................2.17 Sample Reception ..........................................................................................2.19 Sample Drying................................................................................................2.19

CHAPTER 3 : CLASSIFICATION TESTS 3.1 3.2 3.3 3.4

Determination of Moisture Content....................................................................3.1 Determination of Atterberg Limits ....................................................................3.11 Particle Size Distribution .................................................................................3.22 Determination of Organic Content...................................................................3.32

3.5

Standard Description and Classifications ........................................................3.34

CHAPTER 4 : DRY DENSITY - MOISTURE CONTENT RELATIONSHIPS 4.1

General Requirements ......................................................................................4.1

4.2 4.3 4.4 4.5

Sample Preparation..........................................................................................4.2 Standard Compaction using 2.5 kg Rammer .....................................................4.8 Heavy Compaction using 4.5 kg Rammer........................................................4.19 Vibrating Hammer Method ..............................................................................4.19

I

CHAPTER 5 : STRENGTH TESTS: CALIFORNIA BEARING RATIO AND DYNAMIC CONE PENETROMETER TEST 5.1

California Bearing Ratio (CBR) Test..................................................................5.1

5.2

Dynamic Cone Penetrometer (DCP) Test........................................................5.21

CHAPTER 6 : DETERMINATION OF IN-SITU DENSITY 6.1 6.2 6.3

Introduction.......................................................................................................6.1 Sand Replacement Method...............................................................................6.1 Core Cutter Method ........................................................................................6.10

CHAPTER 7 : TESTS FOR AGGREGATES AND BRICKS 7.1 7.2 7.3 7.4

Determination of Clay and Silt Contents in Natural Aggregates .........................7.1 Particle Size Distribution of Aggregates.............................................................7.5 Shape Tests for Aggregates .............................................................................7.9 Fine Aggregate : Density and Absorption Tests ...............................................7.15

7.5 7.6 7.7 7.8

Coarse Aggregate : Density and Absorption Tests ..........................................7.21 Aggregate Impact Value .................................................................................7.26 Aggregate Crushing Value and 10% Fines Value ............................................7.32 Tests for Bricks...............................................................................................7.39

CHAPTER 8 : TESTS OF CEMENT 8.1 8.2 8.3

Fineness of Cement..........................................................................................8.1 Setting Time of Cement ....................................................................................8.2 Compressive Strength of Cement .....................................................................8.5

CHAPTER 9 : TESTS ON CONCRETE 9.1

Slump Test .......................................................................................................9.1

9.2

Crushing Strength of Concrete ..........................................................................9.5

CHAPTER 10 : TEST FOR BITUMEN AND BITUMINOUS MATERIALS 10.1 10.2 10.3 10.4

Bitumen Penetration Test ...............................................................................10.1 Bitumen Softening Test ..................................................................................10.6 Specific Gravity Test of Bitumen ..................................................................10.12 Bitumen Extraction Tests .............................................................................10.16

10.5 10.6 10.7 10.8

Flash Point and Fire Point Tests of Bitumen .................................................10.33 Viscosity Test of Bitumen .............................................................................10.41 Distillation of Cut-Back Asphaltic (Bituminous) Products ...............................10.51 Float Test of Bitumen ...................................................................................10.57 II

CHAPTER 10 : TEST FOR BITUMEN AND BITUMINOUS MATERIALS 10.9 10.10 10.11 10.12

Marshall Stability and Flow ..........................................................................10.60 Bulk Specific Gravity of Compacted Bituminous Mixtures Test .....................10.76 Maximum Theoretical Specific Gravity of Paving ..........................................10.81 Spray Rate of Bitumen .................................................................................10.86

CHAPTER 11 : STEEL REINFORCEMENT TESTS 11.1

General Requirements ...................................................................................11.1

11.2 11.3

Tension Test of Steel Reinforcing Bar ............................................................11.8 Bend Test of Reinforcing Bar .......................................................................11.14

III

Standard Test Procedures

CHAPTER 1

Definitions, Symbols and Units

CHAPTER 1 DEFINITIONS, SYMBOLS AND UNITS

1.1

Scope

This standard sets out the basic terminology, definitions, symbols and units used in the various parts of the manual, and refers specifically to soils, although some terms may also be applicable when testing other materials. Only the terms commonly in use and most likely to be met in the more routine tests on soils have been included. Conversion factors and other useful data are also included. 1.2

Terminology

The following terminology applies to the soil testing standards. 1.2.1

Soil. An assemblage or mixture of separate particles, usually of mineral composition but sometimes of organic origin, which can be separated by gentle mechanical means and which includes variable amounts of water and air (and sometimes other gases). A soil commonly consists of a naturally occurring deposit, but the term is also applied to made ground consisting of replaced natural soil or man-made materials exhibiting similar behaviour, e.g. crushed brick, crushed rock, pulverised fuel ash or crushed blast-furnace slag.

1.2.2

Cohesive soil. Soil which because of its fine-grained content will form a mass which sticks together at suitable moisture contents.

1.2.3

Cohesionless soil. Granular soil consisting of particles which can be identified individually by the naked eye or by using a magnifying glass, e.g. gravel, sand.

1.3

Definitions

1.3.1

Sample. A portion of soil taken as being representative of a particular deposit or stratum.

1.3.2

Specimen. A portion of a sample on which a test is carried out.

1.3.3

Sampling. The selection of a representative portion of a material.

1.3.4

Quartering. Reducing the size of a large sample of material to the quantity required for test by dividing a circular heap, by diameters at right angles, into four more or less equal portions, removing two diagonally opposite quarters, and thoroughly mixing the two remaining quarters together so as to obtain a truly representative half of the original mass. The process is repeated until a sample of the required size is obtained.

1.3.5

Riffling. The reduction in quantity of a large sample of material by dividing the mass into two approximately equal portions by passing the sample through an appropriately sized sample divider (“riffle box”). The process is repeated until a sample of the required size is obtained. When dividing some coarse-grained materials a combination of quartering and riffling methods may be necessary on different sized fractions of the sample.

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Definitions, Symbols and Units 1.3.6

Dry soil. Soil that has been dried to constant mass at a temperature of 1050C to 1100C. Other drying temperatures. e.g. 600C, may be specified for particular tests.

1.3.7

Moisture content (w). The mass of water which can be removed from the soil, usually by heating at 105 0C, expressed as a percentage of the dry mass. The term water content is also widely used.

1.3.8

Liquid limit (LL). The moisture content at which a soil passes from the liquid to the plastic state, as determined by the liquid limit test.

1.3.9

Plastic limit (PL). The moisture content at which a soil on losing water passes from plastic state to semi-brittle solid state and becomes too dry to be in a plastic condition as determined by the plastic limit.

1.3.10

Plasticity index (PI). The numerical difference between the liquid limit and the plastic limit of a soil : PI = LL – PL

1.3.11

Non-plastic. A soil with a plasticity index of zero or one on which the plastic limit cannot be determined.

1.3.12

Liquidity index (IL). The ratio of the difference between moisture content and plastic limit of a soil, to the plasticity index :

IL =

w - PL PI

1.3.13

Shrinkage limit (ws). The moisture content at which a soil on being dried ceases to shrink.

1.3.14

Linear shrinkage (LS). The change in length of a bar sample of soil when dried from about its liquid limit, expressed as a percentage of the initial length.

1.3.15

Bulk density (ρ). The mass of material (including solid particles and any contained water) per unit volume including voids.

1.3.16

Dry density (ρd ). The mass of the dry soil contained in unit volume of undried material :

ρd =

100ρ 100 + w

1.3.17

Particle density (ρ s). The average mass per unit volume of the solid particles in a sample of soil where the volume includes any sealed voids contained within the solid particles.

1.3.18

Particle size distribution. The percentages of the various grain sizes present in a soil as determined by sieving and sedimentation.

1.3.19

Test sieve. A sieve complying with a recognised Standard.

1.3.20

Cobble fraction. Solid particles of sizes between 200 mm and 60 mm.

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Definitions, Symbols and Units 1.3.21

Gravel fraction. The fraction of a soil composed of particles between the sizes of 60 mm and 2 mm. The gravel fraction is subdivided as follows : Coarse gravel Medium gravel Fine gravel

1.3.22

Sand fraction. The fraction of a soil composed of particles between the sizes of 2.0 mm and 0.06 mm. The sand fraction is subdivided as follows : Coarse sand Medium sand Fine sand

1.3.23

60 mm to 20 mm 20 mm to 6 mm 6 mm to 2 mm

2.0 mm to 0.6 mm 0.6 mm to 0.2 mm 0.2 mm to 0.06 mm

Silt fraction. The fraction of a soil composed of particles between the sizes of 0.06 mm and 0.002 mm. The silt fraction is subdivided as follows : Coarse silt Medium silt Fine silt

0.06 mm to 0.02 mm 0.02 mm to 0.006 mm 0.006 mm to 0.002 mm

1.3.24

Clay fraction. The fraction of a soil composed of particles smaller in size than 0.002 mm.

1.3.25

Fines fraction. The fraction of a soil composed of particles passing a 63 µm test sieve. Note that this includes all material of silt and clay sizes, and a little fine sand. For most practical purposes, the limiting sieve size can be taken to be 75 µm.

1.3.26

Voids. The spaces between solid particles of soil.

1.3.27

Voids ratio (e). The ratio between the volume of voids (air and water) and the volume of solid particles in a mass of soil:

e = 1.3.28

ρs - 1 ρd

(see 1.3.16 and 1.3.17)

Porosity (n). The volume of voids (air and water) expressed as a percentage of the total volume of a mass of soil.

n =

e x 100 (%) l + e

1.3.29

Saturation. The condition in which all the voids in a soil are completely filled with water.

1.3.30

Degree of saturation (Sr ). The volume of water contained in the void spaces between soil particles, expressed as a percentage of the total voids:

Sr =

w ρs (%) e

(see 1.3.7; 1.3.17; 1.3.27)

1.3.31

Compaction. The process of packing soil particles more closely together by rolling or other mechanical means, thus increasing the dry density of the soil.

1.3.32

Optimum moisture content. The moisture content at which a specified amount of compaction will produce the maximum dry density. MAY 2001

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Definitions, Symbols and Units 1.3.33

Maximum compacted dry density. The dry density obtained using a specified amount of compaction at the optimum moisture content.

1.3.34

Relative compaction. The percentage ratio of the dry density of the soil to the maximum compacted dry density of a soil when a specified amount of compaction is used.

1.3.35

Dry density / moisture content relationship. The relationship between dry density and moisture content of a soil when a specified amount of compaction is used.

1.3.36

Percentage air voids (Va). The volume of air voids in the soil expressed as a percentage of the total volume of the soil :

 ρ ρ w  Va = 1 - d  w +   100 (%) ρ w  ρs 100    (see 1.3.7; 1.3.16; 1.3.17; 1.3.37) 1.3.37

Air voids line. A line on a graph showing the dry density / moisture content relationship for soil containing a constant percentage of air voids. The line can be calculated from the equation :

ρd = ρw

where,

ρd ρw Va ρs w

Va   1 - 100  1 w  +   100   ρs

is the dry density of the soil (Mg/m3); is the density of water (Mg/m3); is the volume of air voids in the soil, expressed as a percentage of the total volume of the soil; is the particle density (Mg/m3); is the moisture content, expressed as a percentage of the mass of dry soil.

1.3.38

Saturation line (zero air voids line). A line on a graph showing the dry density / moisture content relationship for soil containing no air voids. It is obtained by putting Va = 0 in the equation given in definition 1.3.37.

1.3.39

Limiting densities. The dry densities corresponding to the extreme states of packing (loosest and densest) at which the particles of a granular soil can be placed.

1.3.40

Maximum density (ρdmax). The maximum dry density at the densest practicable state of packing of particles of a granular soil.

1.3.41

Minimum density (ρdmin). The minimum dry density at the loosest state of packing of dry particles which can be sustained in a granular soil.

1.3.42

Maximum (minimum) porosity or voids ratio. The porosity or voids ratio corresponding to the minimum (maximum) dry density as defined above.

1.3.43

California bearing ratio (CBR). The ratio (expressed as a percentage) of the force required to cause a circular piston of 1935 mm2 cross-sectional area to penetrate the soil from the surface at a constant rate of 1 mm/min, to the force required for similar penetration into a standard sample of crushed rock. The ratio is determined at penetrations of 2.5 mm and 5.0 mm, and the higher value is used. MAY 2001

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Definitions, Symbols and Units

1.3.44

Penetration resistance. The force required to maintain a constant rate of penetration of a probe, e.g. a CBR piston, into the soil.

1.3.45

Consolidation. The process whereby soil particles are packed more closely together over a period of time by application of continued pressure. It is accompanied by drainage of water from the voids between solid particles.

1.3.46

Pore water pressure (u w). The pressure of the water in the voids between solid particles.

1.3.47

Excess pore pressure. The increase in pore water pressure due to the application of an external pressure or stress.

1.3.48

Swelling. The process opposite to consolidation, i.e. expansion of a soil on reduction of pressure due to water being drawn into the voids between particles.

1.3.49

Swelling pressure. The pressure required to maintain constant volume, i.e. to prevent swelling, when a soil has access to water.

1.3.50

Permeability. The ability of a material to allow the passage of a fluid. (Also known as hydraulic conductivity.)

1.3.51

Piping. Movement of soil particles carried by water eroding channels through the soil, leading to sudden collapse of soil.

1.3.52

Erosion. Removal of soil particles by the movement of water.

1.3.53

Dispersive (erodible) clays. Clays from which individual colloidal particles readily go into suspension in particularly still water.

1.3.54

Shear strength. The maximum shear resistance which a soil can offer under defined conditions of effective stress and drainage.

1.4

Greek Alphabet

A number of the symbols traditionally used in soils testing are taken from the Greek alphabet. This is reproduced below for reference purposes: Capital A B Γ ∆ Ε Z H Θ I K Λ M

Small α β γ δ ε ζ η θ ι κ λ µ

Name alpha beta gamma delta epsilon zeta eta theta iota kappa lambda mu

Capital N Ξ O Π P Σ T Y Φ X ψ Ω

MAY 2001

Small ν ξ ο π ρ σ τ υ φ χ ψ ω

Name nu xi omicron pi rho sigma tau upsilon phi chi psi omega

Page 1.5

Standard Test Procedures

CHAPTER 1

Definitions, Symbols and Units 1.5

Symbols and Units

The following symbols are used in the standards in the manual. The symbols generally conform to international usage. The units are those generally used. An asterisk indicates that no unit is used. Term Moisture content Liquid limit Plastic limit Shrinkage limit Plasticity index Liquidity index Bulk density Dry density Particle density Density of water Voids ratio Porosity Degree of saturation Percentage air voids Maximum dry density Minimum dry density Maximum voids ratio Minimum voids ratio California bearing ratio Mean particle diameter Percentage by mass finer than D Elapsed time Unconfined compressive strength

Symbol w LL PL ws PI IL ρ ρd ρs ρw e n Sr Va ρdmax . ρdmin. emax . emin. CBR D K t qu

Unit % % % % % * Kg/m3 Kg/m3 Kg/m3 Kg/m3 * % % % Kg/m3 Kg/m3 * * % mm or µm % minutes or second kPa

1.6

Conversion Factors and Useful Data

1.6.1

General. The modern form of the metric system is known as the SI system. SI is the accepted abbreviation for Systeme International d’Unites (International System of Units), the system finally agreed at an international conference in 1960.

1.6.2

Conversion factors. Conversion factors for SI and imperial units are given in Table 1.6.1.

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Definitions, Symbols and Units Table 1.6.1

CONVERSION FACTORS, IMPERIAL AND SI UNITS.

Imperial to SI Length

Area

Volume

Mass

Density Force Pressure

1.609 0.3048 25.4 0.4045 0.09590 645.2 0.764 0.02832 4.546 3.785 28.32 16.39 16387 1.016 0.4536 453.6 28.35 0.01602 9.964 4.448 0.04788 6.895 47.88

km m mm hectare (ha) m2 mm2 m3 m3 litre litre litre ml mm3 Mg (tonne) kg g g Mg/m3 (g/cm3) kN N kN/m2 (kPa) kN/m2 N/m2 (Pa)

: : : : : : : : : : : : : : : : : : : : : : :

mile foot (ft) inch (in) acre square foot square inch cubic yard cubic foot gallon (UK) gallon (USA) cubic foot cubic inch cubic inch ton pound (lb) pound ounce (oz) pound per cubic foot ton force pound force lb f/sq ft lb f/sq in lb f/sq ft

SI to Imperial 0.6215 3.281 0.03937 2.471 10.76 0.001550 1.3089 35.34 0.2200 0.2642 0.03531 0.06102 0.9842 2.205 0.03527 62.43 0.1004 0.2248 20.89 0.1450 0.02089

NOTE 1 litre (L) = 1,000 cm3 = 1,000 mL 1 kN = 1,000 N 1MN/m2 = 1 N/mm2

1 tonne = 1,000 kilograms (kg) 1 kg = 1,000 grams (g) 1 kgf = 9.81 N 1 tonne f = 9.81 kN

1 Megagram (Mg)/m3 = 1,000 kg/m3 1 Megagram/m3 = 1 g/cc

Examples To convert imperial to SI, e.g. to convert feet to metres, multiply number of feet by 0.3048. To convert SI to imperial, e.g. to convert metres to feet, multiply number of metres by 3.281. 1.6.3

Useful data and information

1.6.3.1

Standard gravity. The international standard acceleration due to the earth’s gravity is accepted as; g = 9.80665 m/s2 although it varies slightly from place to place. For practical purposes g = 9.81 m/s2, the conventional reference value used as a common basis for measurements made on the Earth.

1.6.3.2

Mass. The kilogram (kg) is equal to the mass of the international platinum prototype kept by Bureau International des Poids et Measures (BIPM) at Sevres. It is the only basic quantity to be a multiple unit : 1 kg = 1,000 g (grams) MAY 2001

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Standard Test Procedures

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Definitions, Symbols and Units

There is no SI unit of ‘weight’. When ‘weight’ is used to mean the force due to gravity acting on a mass, the mass (kg) must be multiplied by g(9.81 m/s2) to give the force in Newton’s (N). 1.6.3.3

Density. The megagram per cubic metre (Mg/m3) is the density unit adopted for soil mechanics. It is 1000 times larger than the kilogram per cubic metre, the basic SI unit, and is equal to one gram per cubic centimetre : 1 Mg/m3

= 1 g/cm3 = 1,000 kg/m3

The density of soil particles (particle density) is expressed in Mg/m3, which is numerically equal to the specific gravity (now obsolete). Using Mg/m3, the density of water is unity. 1.6.3.4

Force. The Newton (N) is that force which, applied to a mass of 1 kilogram, gives it an acceleration of 1 metre per second per second. 1 N = 1 kg m/s2 The kilonewton (kN) is the force unit most used in soil mechanics: 1 kN = 1,000 N = approximately 0.1 tonne f or 0.1 ton f

1.6.3.5

Pressure and stress. The Pascal (Pa) is the pressure produced by a force of 1 Newton applied, uniformly distributed, over an area of 1 square metre. The Pascal has been introduced as the pressure and stress unit, and is exactly equal to the Newton per square metre: 1 Pa = 1 N/m2 In dealing with soils the usual unit of pressure is kilonewton per square metre (kN/ m2), or kilopascal: 1 kN/m2 = 1 k Pa = 1,000 N/m2 The bar is not an SI unit but is sometimes encountered in fluid pressure: 1 bar = 100 kN/m2 = 100 k Pa = 1000 mb (millibars)

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Definitions, Symbols and Units 1.6.3.6

Comparison of BS and ASTM sieve sizes BS sieve aperture size 75 mm 63 50 37.5 28 20 14 10 6.3 5 3.35 2 1.18 600 µm 425 300 212 150 75 63

Sieves to ASTM D422 Nearest designation Aperture size 3 inch 75 mm 21/2 inch 63.5 2 inch 50.8 11/2 inch 38.1 1 inch 25.4 ¾ inch 19.05 3 /8 inch 9.52 No. 4 4.75 No. 6 3.35 No. 8 2.36 No. 10 2.00 No. 16 1.18 No. 20 850 µm No. 30 600 No. 40 425 No. 50 300 No. 60 250 No. 70 212 No. 100 150 No. 140 106 No. 200 75 No. 230 63

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CHAPTER 2

Sampling

CHAPTER 2 SAMPLING

2.1

General

This standard deals with the sampling of soils, bricks, aggregates, cement, concrete, bitumen and bituminous materials. A sample is a small quantity of material which represents in every way, a much larger quantity of material. In taking a sample we are not usually attempting to select the best or worst examples of the materials used but the typical material as used in the works. Sampling should therefore be done on a completely random basis and personal preferences should not be allowed to interfere with the selection. 2.2

Sampling of Soils

Samples are of one of two main types: disturbed or undisturbed. 2.2.1

Disturbed samples. Usually taken with a pick and shovel, scoop or other appropriate hand tool, care should be taken to prevent coarse material from rolling off the sides of the tool, which will leave behind too fine a sample. Disturbed samples can be taken in test pits, trenches or similar excavations, auger holes and boreholes. Disturbed samples can also be taken from stockpiles of material and from material laid during road construction. Small disturbed samples can also be available as the result of carrying out other work, e.g. samples from the Standard Penetration Test (SPT) shoe, and samples from the cutting shoe of undisturbed sample tubes.

2.2.1.1

Techniques. The sampling technique employed will be influenced by factors such as the type and quantity of material being sampled, the equipment available, physical constraints of the sampling location, the intended use of the material being sampled.

2.2.1.1.1 Test pits. Based upon the changes in moisture condition, colour consistency, soil type, structure etc., the sides of the test pit are inspected to their full depth and any observable change is recorded with depth. Any vegetation growing around the upper edge of the test pit should be removed. Now every distinguishable gravel, soil or sand layer should separately sampled by holding a spade or canvas sheet at the lower level of the layer against the side of the pit and by cutting a sheer groove to the full depth of the layer with a pick or spade. If the test pit had been dug sometimes before, then weathered material should be removed from the surface before sampling. The material obtained in this way should be placed in sample bags. The canvas sheet may also be spread out on the floor of the test pit if this is more convenient. Once all the layers have been sampled, all of the material from a particular layer must be combined on either a clean, hard, even surface or on a canvas sheet and properly mixed with a spade. The material sampled should not be contaminated with other material. Samples should preferably be sealed in airtight tins and should fill the tin completely. Duplicate or even triplicate samples should be taken. If the bulk sample is too large, quarter or riffle out into sample bags a representative sample of the layer as explained earlier. The sample bags must be clearly and indelibly marked, so that the samples can be identified in the laboratory. All test pits should be properly fenced to safeguard villagers and animals.

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Sampling Caution: It is recommended that in any case no excavation deeper than 1.5m should be made unless: a) It is properly propped and braced b) The gradient of the sides is at least equal to the natural angle of repose of the soil. c) It is in firm rock. 2.2.1.1.2 Stockpiles. When sampling from a stockpile the material on the top and sides of the pile must not be used as this is generally coarser than the interior of the stockpile. The correct procedure is to dig small holes in the stockpile (Figure 2.2.1) and sample the material from the base of these holes. At least ten holes must be made at different places on the stockpile and the materials obtained should be thoroughly mixed together. However, stockpiles are often scraped together in natural material with bulldozers, in which case it is better to wait until the stockpile has been completed before taking samples. Samples will be carried out using hand tools. Sampling can also be done using a mechanical loader-digger (in large stockpiles). Samples may be collected by using two shovels perpendicularly, one to prevent material falling on to the samples and one to clean off and take the sample (Figure 2.2.2). Samples may also be collected by digging a groove from the top to the bottom of the stockpile (Figure 2.2.3). Table 2.2.1 Type of Test Moisture content Atterberg limits Particle size distribution (sieving) Particle size distribution (sedimentation) Particle density MDD test California bearing ratio pH value

Finegrained 50 g 1 kg 150 g 250 g 1.5 kg 80 kg 6 kg 150 g

Soil Group* MediumCoarse-grained grained 350 g 4 kg 1.5 kg 2.5 kg 2.5 kg 17 kg 100 g** 100 g** 2 kg 4 kg 80 kg 80 kg 6 kg 12 kg 600 g 3.5 kg

Mass of sample required for each test on disturbed samples is given in Table 2.2.1. These masses include some allowance for drying, wastage and rejection of stones where required. Multiply these masses by the number of tests required. Where appropriate, these masses assume that soils are susceptible to crushing. ** Sufficient to give the stated mass of fine-grained material. * Soil group i) Fine-grained soils: Soils containing not more than 10% retained on a 2 mm test sieve. ii) Medium-grained soils: Soils containing more than 10% retained on a 2 mm test sieve but not more than 10% retained on a 20 mm test sieve. iii) Coarse-grained soils: Soils containing more than 10% retained on a 20 mm test sieve but not more than 10% retained on a 37.5 mm test sieve. A soil shall be regarded as belonging to the finest-grained group as appropriate under the above definitions. 2.2.1.1.3 Road pavement layers. When sampling from a partly constructed road pavement, for example in crushed brick consolidation work, several small areas should be marked out and all the material must be collected from the excavated holes or trenches of each area. Care must be taken to ensure all the fine material is collected by using small tools like brushes. Undisturbed samples are not generally taken in roadwork layers. Corecutters used primarily in fine grained soils for in-situ density determination can also provide an undisturbed sample.

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Sampling 2.2.2

Undisturbed samples. It is extremely difficult to obtain a truly “undisturbed” sample. Samples generally described as undisturbed can be taken in the form of excavated blocks, from which test specimens are later prepared, or in metal tubes fitted with sharpened cutting shoes. Sample tubes of this type are driven or jacked into the ground using a variety of methods and the sample are more frequently taken in boreholes using machine-operated equipment, but can also be obtained in test pits using handoperated equipment.

2.2.2.1

Techniques

2.2.2.1.1 Block samples. Cohesive material in test pits or other locations can be sampled in blocks by carefully cutting away surrounding material and then undercutting the block to remove it. 2.2.2.1.2 Samples in moulds and tubes. Metal tubes for taking undisturbed samples are commonly 75 mm or 100 mm φ and 450 mm long (known as U3 or U4 tubes) or 38 mm φ and 230 mm long. The latter are convenient for use in test pits, when they can be driven by using a hammer or preferably by a driving dolly. On ejection and trimming, the samples are suitable sizes for triaxial testing. The larger sample tubes are fitted with detachable cutting shoes and are generally driven using mechanised equipment or hand-operated hammering device. Considerable care is required to maintain the verticality of the tube when driving it. Samples in tubes or block sample should be carefully waxed after removing just enough of the top of the sample with a palette knife to form a flat surface. 2.2.3

Labeling sample. The sample must be comprehensively labeled. The label should include information from the following list, as appropriate; a) b) c) d) e) f) g) h) i) j) k) l) m) n)

Name of the project Name of the sampler Date and time of sampling Location within project: chainage; offset; carriageway; construction area, etc. Depth of sample below reference datum, e.g. finished road level Sample number Description of the layer Description of the material Test pit; borehole; auger hole number Type of sample Sampling method Supplier’s name Source of material Number and type of container(s), and the number(s) with which the containers are marked o) How samples are being sent p) Registration number of sampled truck q) Additional information, e.g. how the material was processed before sampling. Metal tubes should be labeled on the side of the tube and not on the end cap. The end of the metal tube marking the top of the stratum should be so marked (i.e. with a T). The present system uses pre-printed ‘Sample Record Cards’, shown as Form 2.2.1.

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Sampling 2.3

Sampling of Bricks

2.3.1

Scope. The scope of this standard is to provide methods of sampling bricks without bias and to give guidance as to the frequency and size of samples required for testing. The physical form of the consignment of bricks will normally dictate the choice and method of sampling. No special equipment is required for sampling bricks.

2.3.2

Sampling methods. The sample may be drawn either by a) random sampling; or b) stratified sampling. 1.

Sampling in motion

Whenever practicable a sample shall be taken whilst the bricks are being moved for example during loading or unloading. The lot shall be divided into a number of convenient portions (not less than ten) such that when equal number of bricks are drawn from each of these portions the number of bricks required for the inspection and testing is provided. 2.

Stacked materials

The number of bricks required for the tests should be sampled from a consignment of not more than 15,000 units for machine-made bricks and 5,000 units for hand-made bricks. The number of bricks required for all the various tests is detailed in Table 2.2. The bricks should be sampled at random so that each brick in the stack or stacks has an equal chance of being chosen, including those bricks within the stacks. This may require the dismantling of part of the stack in order to reach the bricks inside. This will be difficult unless the stacks are small. If possible, an equal sub-sample of not more than 4 bricks should be taken from at least 6 real or imaginary similarly-sized sections of the consignment. 3.

Brick soling

Bricks laid as whole bricks such as in herring bone paving or in shoulder work should be sampled from an area of one square metre marked on the road. All whole bricks within the marked area should be returned to the laboratory as one sample. Several such areas may require to be marked out in order to collect the number of bricks required for the various tests. 4.

Crushed brick

Crushed brick laid as a road pavement layer should be sampled in accordance with 2.2.1.1.3. It is most important that all fine material is removed from the test hole. 2.3.3

Treatment of samples. When the sample is to provide bricks for more than one tests the total number shall be collected together and then divided by taking bricks at random from within the total sample to form each successive sub-sample. Crushed bricks may be riffled or quartered if necessary before transportation, provided that the requirements for minimum test sample weights are met.

2.3.4

Number of bricks required Table 2.3.1 gives a guide as to the number of brick required against the specified test.

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Sampling Table 2.3.1 Number of bricks required for testing Purpose

Number of bricks required for sample

Dimensional checks Soluble salt content Compressive strength Water absorption 2.3.5

24 10 12 10

Sample identification. The following information should be clearly indicated on the sampling certificate by the sampling personnel. a) b) c) d) e) f) g) h) i)

Sampling agent Contract name / work name Client name Where the bricks will be used Supplier of bricks Date of manufacture Type of brick Size of consignment Type of test required.

A sampling certificate is shown as Form 2.3.1.

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Form 2.3.1

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Sampling 2.4

Sampling of Aggregates

2.4.1

Definitions a) Batch. A definite quantity of some commodity manufactured or produced under conditions which are presumed uniform. b) Sampling increment. A quantity of material taken at one time from a larger body of material. When sampling aggregates, the material taken by single operation of a scoop should be treated as a sampling increment. c) Bulk sample. An aggregation of the sampling increments. d) Laboratory sample. A sample intended for laboratory inspection or testing. e) Test portion. The material used as a whole in testing or inspection.

2.4.2

Equipment a) A small scoop, to hold a volume of at least 1 L (about 1.5 kg). This scoop is used for sampling aggregates of nominal sizes less than 5mm. b) A large scoop, to hold a volume of at least 2 L (about 3 kg.). This scoop is used for sampling any grading of aggregate but is required particularly for aggregates of nominal sizes greater than 5mm. c) Containers, clean and non-absorbent for collecting the increments of a sample. d) Containers, clean and impervious for collecting samples for sending to the laboratory. They should be durable and at least 100 micron thick. e) A sample divider, appropriate to the maximum size to be handled. A riffle box is suitable or a flat shovel and a flat metal tray for use in quartering.

2.4.3

Procedure for sampling coarse, fine and all-in aggregate a) Only an experienced person should be allowed to sample. b) Obtain a bulk sample by collecting, in the clean containers, sufficient number of increments to provide the required quantity of aggregate for all the tests to be made. However, the number of increments should be not less than those given in Table 2.4.1. Table 2.4.1 Minimum number of sampling increments Nominal size of aggregate

28 mm and larger 5 mm to 28 mm 5 mm and smaller

Nominal size of sampling increments Large scoop 20 10 10 half scoops

Nominal size of sampling increments Small scoop 10

Approximate minimum mass for normal density aggregate kg. 50 25 10

c) Take increment from different parts of the batch in such a way as to represent the average quality. d) When sampling from heaps of aggregates, take the required number of increments from positions evenly distributed over the whole surface of the heap. e) When sampling from ground level, care should be taken to avoid contamination of the material. f) When sampling form material in motion, calculate the sampling times to give the required number of sampling increments, ensuring that they are randomly distributed throughout the batch of aggregate. g) When sampling from a falling stream of aggregate, take increments from the whole width of the stream. h) When sampling from a conveyor belt, stop the conveyor at appropriate times and take all the material from a fixed length of the conveyor. MAY 2001

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Sampling i) j)

Combine all the increments and either dispatch the bulk sample or reduce it and then dispatch the smaller sample for testing. Never sample manually form a moving conveyor.

2.4.4

Reduction of sample. It is sometimes necessary to reduce the mass of bulk sample at site substantially. This shall be done in such a way to preserve at each stage a representative part of the bulk sample. The reduction of sample should be done in accordance with 2.9.1.1.

2.4.5

Dispatching of samples. The samples should be transferred completely to containers which shall then be sealed for dispatch. Individual packages should preferably not exceed 30 kg. a) Information accompanying the samples. Each sample should contain a card, suitably protected from damage by moisture and abrasion, giving details of the dispatcher and the description of the material. b) Sampling certificate Each sample, or group of samples from a single source, shall be accompanied by a certificate, from the person responsible for taking the sample. The certificate shall include as much as is appropriate of the following information. i.) ii.) iii.) iv.) v.) vi.) vii.) viii.) ix.) x.) xi.) xii.)

Name of testing agent Client name Contractor’s name Contract name Name and location of source Date and time of sampling Method of sampling Identification number Description of sample Tests required Any other information that may be useful to the tester Name and signature of sampler

A sampling certificate is shown as Form 2.4.1.

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Sampling 2.5 2.5.1

Sampling of Cement Introduction. In a general sense of the word, cement can be described as a material with adhesive and cohesive properties which make it capable of bonding mineral fragment into a compact whole mass. The main components of cement are compounds of lime. One of the properties of cements is to be able to set under water by virtue of a chemical reaction with the water. In civil engineering cement is normally confined to calcareous, hydraulic cement. The variability of the proportions of the individual mineral content in the cement renders it to different behaviours in both chemical and physical. Table 2.5.1 lists a number of cements and their designation. Table 2.5.1 Main types of Portland cement General description Ordinary Portland Rapid-hardening Portland Extra rapid-hardening Portland Low heat Portland Modified cement Sulphate-resisting cement White Portland Slag cement

ASTM description Type I Type III Type IV Type II Type V Type S

2.5.2

Scope. This test provides methods for sampling hydraulic cements for testing. The importance of sampling has already been underlined in the introduction.

2.5.3

Equipment. No special equipment is required for sampling cements other than the following: a) Square mouthed shovel; size 2 in accordance with BS 3388. b) Suitable flexible container capable of collecting cement from the nozzle of a pump. c) Other suitable sealable containers. Note. Containers to be used for sampling cement should be watertight and water resistant in order to prevent water ingressing into the sample.

2.5.4

Methods

2.5.4.1

Sampling from concrete batch plant 2.5.4.1a

Bulk cement

a.1 The flexible container is fitted around the discharge nozzle of the silo and cement is allowed to flow into it. a.2 The flexible container is fitted around the discharge nozzle of the cement haulage truck and cement is allowed to flow into it before discharge into the silo. 2.5.4.1b

Bagged cement

Using the random numbers method of sampling decide on the size of a lot and take at random one bag of cement to represent that lot. 2.5.5

Rate of sampling. The rate of sampling is governed by the particular tests required by the specification. Normally the manufacturer delivers cement in batches. One sample is normally taken from each batch.

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Sampling 2.5.6

Test type requirement. For pre-construction approval of cement all tests such as chemical composition, physical properties of: fineness, setting times and compressive strengths are normally required. Upon approval of the cement type, the supplier and manufacturer, cement is procured. The tests required to be carried out to confirm continuous quality during construction are limited due to the length of the tests, however, samples from each batch, for each type of cement, from each supplier from each delivery are taken for routine testing: a) compressive strength b) initial and final setting times c) fineness modulus Other physical tests and chemical tests are normally required once per month from each manufacturer, for each type of cement.

2.5.7

Sampling certificates. A sampling certificate should be issued every time samples of cement are delivered or collected for sampling. The certificate should include at least the following information: a) b) c) d) e) f) g) h) i) j) k)

Name of testing agency Client Manufacturer Client Cement type Location of sample Sample unique identification number Name and signature of sampler Purpose of sampling (test types to be performed) Date of sampling Any other relevant information

2.6

Sampling of Concrete

2.6.1

Scope. The purpose of this test is to provide methods which could be used on site for obtaining from a batch of fresh concrete, representative samples of the quantity required for carrying out the required tests and for making test specimens.

2.6.2

Definitions a) Batch. The quantity of concrete mixed in one cycle of operations of a batch mixer, or the quantity of concrete conveyed ready-mixed in a vehicle, or the quantity of concrete discharged during 1 min. From a continuous mixer. b) Sample. The quantity of concrete, consisting of a number of standard scoopfuls, taken from a batch of concrete. c) Standard scoopful. The quantity of concrete taken by a single operation of the scoop, approximately 5 kg mass of normal weight concrete.

2.6.3

Apparatus a) Scoop, made from minimum 0.8 mm thick non-corrodible metals suitable for taking standard scoopfuls of concrete. b) Container for receiving concrete from a scoop, made of plastic or metal, of 9L minimum capacity. c) Sampling tray, minimum dimensions 900 mm x 900 mm x 50 mm deep, of rigid construction made from a non-absorbent material not readily attacked by cement paste. d) Square mouthed shovel; size 2 in accordance with BS 3388. MAY 2001

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Sampling 2.5.6

Test type requirement. For pre-construction approval of cement all tests such as chemical composition, physical properties of: fineness, setting times and compressive strengths are normally required. Upon approval of the cement type, the supplier and manufacturer, cement is procured. The tests required to be carried out to confirm continuous quality during construction are limited due to the length of the tests, however, samples from each batch, for each type of cement, from each supplier from each delivery are taken for routine testing: a) compressive strength b) initial and final setting times c) fineness modulus Other physical tests and chemical tests are normally required once per month from each manufacturer, for each type of cement.

2.5.7

Sampling certificates. A sampling certificate should be issued every time samples of cement are delivered or collected for sampling. The certificate should include at least the following information: a) b) c) d) e) f) g) h) i) j) k)

Name of testing agency Client Manufacturer Client Cement type Location of sample Sample unique identification number Name and signature of sampler Purpose of sampling (test types to be performed) Date of sampling Any other relevant information

2.6

Sampling of Concrete

2.6.1

Scope. The purpose of this test is to provide methods which could be used on site for obtaining from a batch of fresh concrete, representative samples of the quantity required for carrying out the required tests and for making test specimens.

2.6.2

Definitions a) Batch. The quantity of concrete mixed in one cycle of operations of a batch mixer, or the quantity of concrete conveyed ready-mixed in a vehicle, or the quantity of concrete discharged during 1 min. From a continuous mixer. b) Sample. The quantity of concrete, consisting of a number of standard scoopfuls, taken from a batch of concrete. c) Standard scoopful. The quantity of concrete taken by a single operation of the scoop, approximately 5 kg mass of normal weight concrete.

2.6.3

Apparatus a) Scoop, made from minimum 0.8 mm thick non-corrodible metals suitable for taking standard scoopfuls of concrete. b) Container for receiving concrete from a scoop, made of plastic or metal, of 9L minimum capacity. c) Sampling tray, minimum dimensions 900 mm x 900 mm x 50 mm deep, of rigid construction made from a non-absorbent material not readily attacked by cement paste. d) Square mouthed shovel; size 2 in accordance with BS 3388. MAY 2001

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2.6.4

Sampling procedure. Estimate the number of scoopfuls required for the test(s) by reference to Table 2.6.1. Note. If a shovel is used or other defined apparatus, correlate between the quantity of the scoop and the quantity of the shovel. Note. When sampling from a batch mixer or ready-mixed concrete truck disregard the very first part and the very last part of the discharge. Preferably sample from the middle third of the batch. Note. If the batch to be sampled has been deposited in a heap or heaps of concrete, the parts should whenever possible be distributed through the depth of the concrete as well as over the exposed surface. Table 2.6.1 Quantities of concrete required Test specimen Slump Compacting factor Vebe time Flow index Air content Density 2 cubes 100mm x 100mm 2 cubes 150mm x 150mm 2 beams 100mm x 100 mm x 500mm 2 beams 150mm x 150 mm x 750mm 2 cylinders 150mm x 300mm

2.6.5

number of standard scoopfuls 4 6 4 4 4 6 4 4 6 18 6

Obtaining a sample. Ensure that the equipment is clean. Using the scoop obtain a scoopful of concrete from the central portion of each part of the batch and place it in the container or containers. When sampling from a falling stream pass the scoop through the whole width and thickness of the stream in a single operation. Take the container(s) to the area where the sample is to be prepared for testing or moulding. Sampling from a heap of concrete. Ensure that the shovel is driven into the heap and that concrete is taken to represent the whole mass of the heap by taking a sub-sample from different areas of the heap well spaced over its entire surface area. Combine all sub-samples, agitate and mix well and prepare the sample for testing or moulding.

2.6.6

Protection of samples. At all stages of sampling, transport and handling, the fresh concrete shall be protected against gaining or loosing water and against excessive temperatures.

2.6.7

Certificate of sampling. Each sample shall be accompanied by a certificate of sampling from the person responsible for taking the sample and the certificate shall include at least the following information: a) b) c) d) e) f) g)

Testing agency Client Contract name Location within the structure of concrete Sample identification number Delivery batch note number or any other means of identifying the batch Concrete temperature MAY 2001

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Sampling h) Ambient temperature and weather conditions i) Name of sampler j) Signature of sampler A sampling certificate is shown as Form 2.6.1.

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Sampling 2.7

Sampling of Bitumen Bitumen is normally contained either in metal drums or heated bulk tanks and different methods should be used for sampling each type.

2.7.1

From metal drums the sample must be taken by cutting holes in the side of the drum and removing a sample of bitumen from these holes. Samples should not be taken from the top and bottom of the drum as this may be contaminated during storage and transport.

2.7.2

From a heated bulk tank it is necessary to obtain a sample from the full depth of the tank. This is best done from the top access opening using a purpose-made tube with a closing plug at the bottom, as shown in Figure 2.7.1. The tube is pushed into the full depth of the bitumen, the flap closed and the tube withdrawn. The sample obtained from the tube must be fully mixed before removing a portion for test.

Handle

Cone

Figure 2.7.1

Bitumen Sampling Tube

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Sampling 2.8

Sampling of Bituminous Materials Pre-mixed bituminous materials may be sampled at the asphalt plant or at the site where the material is being laid.

2.8.1

When sampling at the asphalt plant, the whole batch should be discharged into a lorry and then a sample taken from the material in the lorry. This is done in a similar way to sampling from a stockpile with fractions of the sample being taken from at least five different points of the material.

2.8.2

Sampling at the laying site may either be from the paving machine or the laid material. a) When sampling from a paving machine, material should never be taken from the front hopper as segregation often takes place here. Samples should always be taken from the rear screws, a scoop being used to collect material from the ends of the screw. Samples must only be taken when the screws are fully loaded and samples should be taken from both ends. b) When sampling the as laid material, an area to be sampled is marked out and all the material within that area, to the full layer thickness should be removed. Generally it is better to obtain a sample from a number of smaller areas than one big area. On completion of sampling, care must be taken to ensure the areas are repaired to the standard of the original material. Samples of bituminous materials are best transported in a closed tin or small drum. The details of the sample should be recorded, including sample number, date, origin of material, type of material, time of mixing, time of laying, chainage of laid material and weather conditions. It is also necessary to record the temperature after mixing, the temperature at the time of laying and the temperature at the time of rolling.

2.9

Preparing and Transporting Samples

2.9.1

Sample preparation Many samples will require some preparation before being sent to the laboratory for testing, particularly if their large sizes makes them difficult to handle or because they require special protection.

2.9.1.1

Sample reduction. If the sample is delivered larger than required for a particular testing programme, it must be divided to obtain a sample of the required size. In order to ensure the test sample represents the original material, it is necessary to divide the original sample either by quartering or by using a sample divider (Riffle box).

2.9.1.1.1 Quartering. In this method the original sample is placed on a hard clean surface (preferably concrete) and made into a neat circular pile. Using a shovel, this pile is then separated into quarters by making two lines at right angles through the centre of the pile. Two opposite quardrants should then be put aside and the remaining two quadrants should be mixed together to give a smaller sample. If the divided sample is still too large, the procedure should be repeated. Figure 2.9.1 shows the procedure diagrammatically. 2.9.1.1.2 Sample divider. A sample divider, or riffle box, is a purpose-made tool for splitting samples and a riffle box is shown in Figure 2.9.2. The box consists of a number of slots or chutes, alternate ones leading to two separate containers. The total sample is placed into the top hopper and passes down the chutes, half of the sample being collected in each container. The width of the chutes shall be appropriate to the maximum particle

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Sampling 2.8

Sampling of Bituminous Materials Pre-mixed bituminous materials may be sampled at the asphalt plant or at the site where the material is being laid.

2.8.1

When sampling at the asphalt plant, the whole batch should be discharged into a lorry and then a sample taken from the material in the lorry. This is done in a similar way to sampling from a stockpile with fractions of the sample being taken from at least five different points of the material.

2.8.2

Sampling at the laying site may either be from the paving machine or the laid material. a) When sampling from a paving machine, material should never be taken from the front hopper as segregation often takes place here. Samples should always be taken from the rear screws, a scoop being used to collect material from the ends of the screw. Samples must only be taken when the screws are fully loaded and samples should be taken from both ends. b) When sampling the as laid material, an area to be sampled is marked out and all the material within that area, to the full layer thickness should be removed. Generally it is better to obtain a sample from a number of smaller areas than one big area. On completion of sampling, care must be taken to ensure the areas are repaired to the standard of the original material. Samples of bituminous materials are best transported in a closed tin or small drum. The details of the sample should be recorded, including sample number, date, origin of material, type of material, time of mixing, time of laying, chainage of laid material and weather conditions. It is also necessary to record the temperature after mixing, the temperature at the time of laying and the temperature at the time of rolling.

2.9

Preparing and Transporting Samples

2.9.1

Sample preparation Many samples will require some preparation before being sent to the laboratory for testing, particularly if their large sizes makes them difficult to handle or because they require special protection.

2.9.1.1

Sample reduction. If the sample is delivered larger than required for a particular testing programme, it must be divided to obtain a sample of the required size. In order to ensure the test sample represents the original material, it is necessary to divide the original sample either by quartering or by using a sample divider (Riffle box).

2.9.1.1.1 Quartering. In this method the original sample is placed on a hard clean surface (preferably concrete) and made into a neat circular pile. Using a shovel, this pile is then separated into quarters by making two lines at right angles through the centre of the pile. Two opposite quardrants should then be put aside and the remaining two quadrants should be mixed together to give a smaller sample. If the divided sample is still too large, the procedure should be repeated. Figure 2.9.1 shows the procedure diagrammatically. 2.9.1.1.2 Sample divider. A sample divider, or riffle box, is a purpose-made tool for splitting samples and a riffle box is shown in Figure 2.9.2. The box consists of a number of slots or chutes, alternate ones leading to two separate containers. The total sample is placed into the top hopper and passes down the chutes, half of the sample being collected in each container. The width of the chutes shall be appropriate to the maximum particle

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Sampling size of the sample and in general should not be smaller than 1.5 times the maximum particle size of the sample If the sample is still too large, one of the containers may be put aside and the material from the other container is passed through the sample divider again. 2.9.2

Sample transportation All samples should be carefully packed and labeled before transporting them to the laboratory. Sample bags must be strong enough to withstand rough handling and be of a type which prevents loss of fines or moisture from the sample, e.g. thick polythene bags inside jute bags. The use of steel drums for large bulk samples could also be considered. Water samples in glass or plastic containers will require particular care in handling. Undisturbed samples should be placed in wooden boxes and packed in sawdust or similar material to provide added protection. Collision between tubes in transit can easily damage sensitive samples.

2.10

Sample Reception

2.10.1

Registration. Full details of the sample, as written on the label is checked and amended and weighed and must be entered in the laboratory register. A unique number is allocated to the sample and this number is used subsequently on all test sheets for the sample. A copy of the formalised testing programme should accompany the sample through the various stages of testing.

2.10.2

Initial treatment a) Natural moisture content samples should be taken first, as quickly as possible. b) Air drying should be done by leaving the soil spread out in trays or on a hard, clean floor in the laboratory for 2-3 days. c) Oven drying must be done at the correct temperature (110±50C). d) No attempt should be made to quarter down or riffle material which is in lumps or is larger than the size of the riffle-box chutes.

2.10.3

Storage. Storage of all samples should be in an orderly and systematic manner so that they can be subsequently located easily. The storage facility itself should be a secure area, free from the risk of contamination or other harmful influences. Undisturbed samples may be damaged by vibration or corrosion of tubes and should be stored with especial care. Tubes containing wet sandy or silty soils should be stored upright (suitably protected against being knocked over), to prevent possible slumping and segregation of water. The end caps of tube samples which are to be stored for long periods should be sealed with wax, in addition to the wax seal next to the sample itself. Samples which have been tested should not be disposed of without the authority of the laboratory section head.

2.11

Sample Drying Many tests require the material to be drier at the start of the test than the sample as obtained from the field. Some means of drying the sample must, therefore, be utilised. In the case of liquid and plastic limit tests, it is essential that the material is air dried and, as a general rule, it is preferable to dry samples in the air as opposed to drying in

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Sampling size of the sample and in general should not be smaller than 1.5 times the maximum particle size of the sample If the sample is still too large, one of the containers may be put aside and the material from the other container is passed through the sample divider again. 2.9.2

Sample transportation All samples should be carefully packed and labeled before transporting them to the laboratory. Sample bags must be strong enough to withstand rough handling and be of a type which prevents loss of fines or moisture from the sample, e.g. thick polythene bags inside jute bags. The use of steel drums for large bulk samples could also be considered. Water samples in glass or plastic containers will require particular care in handling. Undisturbed samples should be placed in wooden boxes and packed in sawdust or similar material to provide added protection. Collision between tubes in transit can easily damage sensitive samples.

2.10

Sample Reception

2.10.1

Registration. Full details of the sample, as written on the label is checked and amended and weighed and must be entered in the laboratory register. A unique number is allocated to the sample and this number is used subsequently on all test sheets for the sample. A copy of the formalised testing programme should accompany the sample through the various stages of testing.

2.10.2

Initial treatment a) Natural moisture content samples should be taken first, as quickly as possible. b) Air drying should be done by leaving the soil spread out in trays or on a hard, clean floor in the laboratory for 2-3 days. c) Oven drying must be done at the correct temperature (110±50C). d) No attempt should be made to quarter down or riffle material which is in lumps or is larger than the size of the riffle-box chutes.

2.10.3

Storage. Storage of all samples should be in an orderly and systematic manner so that they can be subsequently located easily. The storage facility itself should be a secure area, free from the risk of contamination or other harmful influences. Undisturbed samples may be damaged by vibration or corrosion of tubes and should be stored with especial care. Tubes containing wet sandy or silty soils should be stored upright (suitably protected against being knocked over), to prevent possible slumping and segregation of water. The end caps of tube samples which are to be stored for long periods should be sealed with wax, in addition to the wax seal next to the sample itself. Samples which have been tested should not be disposed of without the authority of the laboratory section head.

2.11

Sample Drying Many tests require the material to be drier at the start of the test than the sample as obtained from the field. Some means of drying the sample must, therefore, be utilised. In the case of liquid and plastic limit tests, it is essential that the material is air dried and, as a general rule, it is preferable to dry samples in the air as opposed to drying in

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Sampling an oven or by other artificial means. The frequent need to dry samples quickly is more often a sign of bad planning than of an efficient laboratory. 2.11.1

Air drying. This is essential for liquid and plastic limit tests and is the preferred procedure for all other tests. The sample should be spread out in a thin layer on a hard clean floor or on a suitable metal sheet. Ordinary corrugated galvanised roofing sheets are perfectly satisfactory for this purpose. The material should be exposed to the sunlight and should be in a layer not more than 20 mm thick. Cohesive materials such as clays, require breaking by hand or with a rubber mallet into small pieces, to allow drying to take place without too much delay. The soil should periodically be turned over and a careful check should be made to ensure the material is removed to a sheltered place if it starts to rain. In the case of soft stone or gravels, care should be taken to ensure only lumps of cohesive fines are broken up and that the actual stone particles are not destroyed. In the case of fine-grained materials, it is generally beneficial to the later stages of testing to pass the dried particles through a No. 4 sieve. Air drying should not normally take longer than 2 to 3 days if carried out correctly.

2.11.2

Oven drying. Oven drying should only be employed where air drying is not possible. Oven drying will not normally have any detrimental effect on the results for sound granular materials such as sand and gravel, but may change the structure of clay soils and thus lead to incorrect test results. Oven drying must never be used in the case of liquid and plastic limit tests. In oven drying the temperature should not exceed 1100C and the material should be dried as quickly as possible by spreading in thin layers on metal trays. Periodically, the material should be allowed to cool before testing is commenced.

2.11.3

Sand-bath drying. In certain cases an oven may not be available but the sample must be dried quickly; sand bath drying may then be utilised. The sand-bath consists simply of a strong metal tray or dish which is filled with clean coarse sand. The sand bath is placed on some form of heater such as a kerosene stove, a gas ring or an electric ring. The sample to be dried is placed in a heatproof dish which is embedded in the surface of the sand. A low heat should be applied so that the sand becomes heated without causing damage to the bath. The sample should be stirred and turned frequently to ensure the material at the base does not become too hot. The material should be allowed to cool before testing is commenced.

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CHAPTER 3 CLASSIFICATION TESTS

3.1

Determination of Moisture Content

3.1.1

General requirements

3.1.1.1

Scope. Water is present in most naturally occurring soils and has a profound effect in soil behaviour. A knowledge of the moisture content is used as a guide to the classification. It is also used as a subsidiary to almost all other field and laboratory tests of soil. The oven-drying method is the definitive method of measuring the moisture contents of soils. The sand-bath method is used, where oven drying is not possible, mainly on site.

3.1.1.2

Definition. The moisture content of a soil sample is defined as the mass of water in the sample expressed as a percentage of the dry mass, usually heating at 1050C, i.e. moisture content, w = M W

x 100 (%)

MD where,

M W = mass of water M D = dry mass of sample

3.1.1.3

Sample requirements

3.1.1.3.1 Sample mass. The mass required for the test depends on the grading of the soil, as follows; a) Fine-grained soils*, not less than 30 grams b) Medium-grained soils*, not less than 300 grams c) Coarse-grained soils*, not less than 3 kg *Soils group i) Fine-grained soils: Soils containing not more than 10% retained on a 2 mm test sieve. ii) Medium-grained soils: Soils containing more than 10% retained on a 2 mm test sieve but not more than 10% retained on a 20 mm test sieve. iii) Coarse-grained soils: Soils containing more than 10% retained on a 20 mm test sieve but not more than 10% retained on a 37.5 mm test sieve. 3.1.1.4

Accuracy of weighing. The accuracy of weighing required for test samples is as follows; a) Fine-grained soils: within 0.01 g. b) Medium-grained soils: within 0.1 g. c) Coarse-grained soils: within 1g.

3.1.1.5

Safety aspects a) Heat-resistant gloves and / or suitable tongs should be used to avoid personal injury and possible damage to samples. MAY 2001

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b) If glass weighing bottles are used they should be placed on a high shelf away from heating elements. c) A heat-insulated pad should always be used to place hot glassware of any description. 3.1.2

Oven-drying method (standard method)

3.1.2.1

Apparatus 1) Thermostatically controlled drying oven capable of operating to 105±50C. 2) Glass weighing bottles or suitable metal containers (corrosion-resistant tins or trays). 3) Balance (to the required sensitivity). 4) Dessicator containing anhydrous silica gel. 5) Scoop, other small tools as appropriate. Optional: Test sieves - 2 mm, 20 mm, 37.5 mm (to check classification of sample, in order to confirm required sample size).

3.1.2.2

Test procedure a) One clean container with the lid (if fitted) is taken and the mass in grams is recorded (m1) together with container number. Note:

The container plus lid or bottle plus stopper should have the same number and be used together.

b) The sample of wet soil is crumbled and placed in the container. The container with the lid on is weighed in grams (m2). c) The lid is removed and both lid and container are placed in the oven. The sample is then dried in a thermostatically controlled drying oven which is maintained at a temperature of 105±50C. A period of 16 to 24 hours is usually sufficient, but this varies with soil type. It will also vary if the oven contains a large number of samples or very wet samples. The soil is considered dry when the differences in successive weighings of the cooled soil at 4 hour intervals do not exceed 0.1% of the original mass. Note. 1) For peats and soils containing organic matter a drying temperature of 600C is to be preferred to prevent oxidation of organic matter. 2) For soils containing gypsum a maximum drying temperature of 80 0C is preferred. The presence of gypsum can be confirmed by heating a small quantity of soil on a metal plate. Grains of gypsum will turn white within a few minutes, but most other mineral grains will remain unaltered. d) The container is removed from the oven. For medium and coarse-grained soils, the lid should be replaced (if fitted) and the sample allowed to cool. For fine-grained soils, the container and lid, or bottle and stopper if used, should preferably be placed in a dessicator and allowed to cool. After cooling, the lids or stoppers should be replaced and the container plus dry soil weighed in grams (m3). 3.1.2.3

Calculation and expression of results Moisture content, w =

=

mass of moisture x 100% mass of dry soil

( mass of container + wet soil) - (mass of container + dry soil) x 100% (mass of container + dry soil) - (mass of container) MAY 2001

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w=

i.e.

m2 − m 3 x 100% m3 − m1

For values up to 10% the moisture content should be expressed to two significant figures, e.g. 1.9%, 4.3%, 9.8%. For moisture contents above 10% express the result to the nearest whole number, e.g. 11%, 27%. Note. If the moisture content is to be related to the Atterberg limits, e.g. for determining the liquidity index, and the soil contains material retained on a 425 µm sieve, the measured moisture content, w (in %), can be corrected to give the equivalent moisture content, wa (in %), of the fraction passing the 425 µm sieve, using the equation :

 100  wa = w   pa  where,

pa is the percentage by dry mass of the portion of the soil sample passing the 425 µm test sieve.

If the particles retained on the 425 µm sieve are porous and absorb water, the amount of absorption should be determined and the value of water calculated from the equation.

wa =

 100 − p a  100 w − wr  pa  pa 

where; wr, is the moisture content of the fraction retained on the 425 µm test sieve. 3.1.2.4

Report. The test report shall contain the following information: a) b) c) d) e)

the method of test used; the moisture content; the temperature at which the soil was dried, if less than 105 0C; the comparison with Atterberg limits, if required (see Note to 3.1.2.3); full details of the sample origin.

The operator should sign and date test sheet. An example of the calculations made is shown in Form 3.1.1. 3.1.3

Sand-bath (subsidiary method)

3.1.3.1

Apparatus i)

Strong metal heatproof tray or dish containing clean sand to a depth of at least 25mm (sand-bath). ii) Moisture content containers for fine soils (excluding glass containers), as used for oven drying. For coarser soils heat-resistant trays 200-250 mm square and 50-70 mm deep, the size depending on the quantity of soil required for test. iii) Heating equipment, such as a bottled gas burner or paraffin pressure stove, or electric hot plate if mains electricity is available. iv) Scoop, spatula, appropriate small tools.

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Standard Test Procedures

Test procedure a) A clean dry container with the lid (if fitted) is weighed, in grams (m1). The number of the container is recorded. b) The sample of wet soil is crumbled, placed in the container and weighed in grams (m2). c) The sand-bath is placed on some form of heater such as a kerosene stove, a gas burner or an electric heater. The sample in its container is embedded in the surface of the sand in the sand-bath. Care should be taken to ensure that the container is not heated too much. The sample should be stirred and turned frequently so that the sample does not burn. Small pieces of white paper will act as an indicator and turn brown if over-heated. To check that the sample is completely dry it should be weighed and returned to the sand-bath for another 15 minutes. If the loss in mass after heating for a further period of 15 min does not exceed the following, the sample may be considered to be dry : Fine-grained soils Medium-grained soils Coarse-grained soils

0.1g 0.5g 5g

d) After drying, the sample is removed from the sand-bath, the container lid (if fitted) is firmly secured in place and the sample is allowed to cool. When cool, the container and the dry soil is weighed in grams (m3). Note. Do not place hot trays onto the unprotected pan of a balance. e) Normally, more than one determination of moisture content is made and the average value is taken. 3.1.3.3

Calculation and expression of results. Calculation and expression of results are identical to those for oven-drying method.

3.1.3.4

Report. Report is also identical to that for oven-drying method.

3.1.4

Speedy Moisture Test

3.1.4.1

General

3.1.4.1.1 Introduction. A rapid test method for determination of moisture in soils is by the use of a calcium carbide gas pressure moisture tester - commonly called the Speedy moisture tester. Soil samples are used in 6, 26 and 200 gram sizes. 3.1.4.1.2 Apparatus. The basic apparatus includes the moisture tester, a scale for weighing the sample, a cleaning brush, a scoop for measuring the calcium carbide reagent and a sturdy carrying case. For the 26 gm sample test, steel balls are used to break down cohesive materials. Calcium carbide reagent is available in cans. This may be a finely pulverized material and should be of a grade capable of producing at least 2.25 cu.ft. of acetylene gas per pound of calcium carbide. In performing the test, in the 26 gram sample unit, three scoops of reagent (approximately 24 grams) and two balls are placed in the large chamber of the tester. When using the 6 gram sample tester, place on level scoopful (approximately 8 grams) of calcium carbide in the larger chamber of the tester. Steel balls are not used with the 6 gm sample tester. MAY 2001

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Speed moisture tester is shown in Figure 3.1.1. 3.1.4.1.3 Preparation of the material. The speedy moisture test gives consistently accurate results in approximately 3 minutes. The material should be prepared for test as follows: a) Sands and fine powders : No preparation necessary. b) Clays, soils and other coarse materials: Use steel ball speedy moisture test. c) Aggregates: No preparation necessary. 3.1.4.1.4 Pre-caution. Five rules should be noted before testing. Make sure that: a) The body or cap, whichever is being used for the material, is perfectly clean and contains no active absorbent from a previous test. b) The material is truly representative of the bulk and carefully weighed. c) The material and the absorbent are kept separate until the cap is tightly secured to the body. d) The material has been thoroughly prepared – ground or pulverized or mixed with sand (if necessary) so that the absorbent can act freely on the material. e) Make sure that the steel ball pulverizes are used when testing clays, soils etc. 3.1.4.2

Procedure a) Weight the desired 6, 26, or 200 gram test sample on the scale. b) Place the soil sample in the cap of the tester. Then, with the pressure vessel in approximately horizontal position, insert the cap in the pressure vessel and seal the unit by tightening the clamp, taking care that no calcium carbide comes in contact with the soil sample until a seal is achieved. c) Raise the moisture tester to a vertical position so that the soil in the cap falls into the pressure vessel. d) Then shake the tester vigorously so that all the lumps will be broken up, permitting the calcium carbide to react with all the available free moisture. When steel balls are used in the tester, the instrument should be shaken with a rotating motion. This will prevent damage to the instrument and eliminate the possibility of soil particles becoming embedded in the orifice leading to the pressure diaphragm. e) Continue shaking for approximately one minute for granular soils and up to three minutes for other soils, to allow for complete reaction between the calcium carbide reagent and free moisture. Time should be permitted to allow dissipation of the heat generated by the chemical reaction. f) When the dial indicator stops moving, read the dial while holding the instrument in a horizontal position at eye level. g) Record the sample weight and the dial reading. h) With the cap of the instrument pointed away from the operator, slowly release the gas pressure. Empty the pressure vessel and examine the material for lumps. If the sample is not completely pulverized, the test should be repeated using a new sample. i) The dial reading is the percent of moisture by wet weight and must be converted to dry weight percent.

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Clamping screw Small weight Helicol

Small brush

Stirrup

Measuring scoop

Cap Large wire handled brush

Rubber cap gasket

Bushing to hold

Stirrup side screw

Adapter nut and filter

Nylon washer

Rubber gauge gasket Standard tester body

Gauges

Figure 3.1.1

a) Speedy moisture tester

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Knife-edge(square shape)

Scale pan

Knife edge (pear shape) Scale link

Scale cradle Agates

Platform base

Figure 3.1.1

b) Speedy moisture tester

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Standard Test Procedures

Expression of results and report Moisture content should be expressed to two significant figures, e.g. 1.9%, 4.3%. Wet weight / dry weight conversion Chart (when steel ball pulverizes are not used) is presented in Table 3.1.1 and the conversion chart (when using steel ball pulverizes) is shown in Figure 3.1.2. The test report shall contain the following information: a) Method of test used, b) The moisture content c) Full details of the sample origin. Table 3.1.1

Wet Weight / Dry Weight Conversion Chart Not Applicable When Steel Ball Pulverizes Used – See Figure 3.1.2 With Calibration Curves on Reverse Side SPEEDY READING Wet Weight Dry Weight 1.0% 1.0% 2.0% 2.1% 3.0% 3.2% 4.0% 4.3% 5.0% 5.4% 6.0% 6.5% 7.0% 7.6% 8.0% 8.7% 9.0% 9.8% 10.0% 11.0% 10.5% 11.7% 11.0% 12.3% 11.5% 13.0% 12.0% 13.6% 12.5% 14.2% 13.0% 14.9% 13.5% 15.6% 14.0% 16.3% 14.5% 16.9% 15.0% 17.6% 15.5% 18.3% 16.0% 19.0% 16.5% 19.7% 17.0% 20.4% 17.5% 21.2% 18.0% 21.9% 18.5% 22.7% 19.0% 23.4% 19.5% 24.2% 20.0% 25.0%

SPEEDY READING Wet Weight Dry Weight 20.5% 25.8% 21.0% 26.5% 21.5% 27.4% 22.0% 28.2% 22.5% 29.0% 23.0% 29.8% 23.5% 30.7% 24.0% 31.5% 24.5% 32.4% 25.0% 33.3% 25.5% 34.2% 26.0% 35.3% 26.5% 36.0% 27.0% 36.9% 27.5% 37.9% 28.0% 38.8% 28.5% 39.8% 29.0% 40.8% 29.5% 41.8% 30.0% 42.8% 30.5% 43.9% 31.0% 44.9% 31.5% 45.9% 32.0% 47.0% 32.5% 48.1% 33.0% 49.2% 33.5% 50.3% 34.0% 51.5% 34.5% 52.6% 35.0% 53.8%

MAY 2001

SPEEDY READING Wet Weight Dry Weight 35.5% 55.0% 36.0% 56.2% 36.5% 57.4% 37.0% 58.7% 37.5% 60.0% 38.0% 61.2% 38.5% 62.6% 39.0% 63.9% 39.5% 65.2% 40.0% 66.6% 40.5% 68.0% 41.0% 69.4% 41.5% 70.9% 42.0% 72.4% 42.5% 73.8% 43.0% 75.4% 43.5% 76.9% 44.0% 78.5% 44.5% 80.1% 45.0% 81.8% 45.5% 83.4% 46.0% 85.1% 46.5% 86.9% 47.0% 88.6% 47.5% 90.6% 48.0% 92.3% 48.5% 94.1% 49.0% 96.0% 49.5% 98.0% 50.0% 100.0%

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3.2

Determination of Atterberg Limits

3.2.1

Scope. As the moisture content of a soil decreases the soil passes from the liquid state to the plastic state to the solid state. The range of moisture contents over which the soil is plastic is used as a measure of the plasticity index. The points at which a soil changes from one state to another are arbitrarily defined by simple tests called the liquid limit test and plastic limit test. These tests are known as the Atterberg limits. The Atterberg limits are empirical tests which are used to indicate the plasticity of fine grained soil by the differentiation between highly plastic, moderately plastic and nonplastic soils. The tests enable classification and identification of the soil to be carried out and give a rough guide to the engineering properties.

3.2.2

Sample preparation. It is preferable not to dry the soil before preparation for the test. Two preferred methods of preparation are described, depending on whether the soil contains a significant proportion of particles larger than the 425 µm sieve.

3.2.2.1

Method for fine soils. If the soils contains few or no particles retained on a 425 µm sieve, take a representative sample weighing about 500 g, chop it up and mix thoroughly for at least 10 minutes with distilled water to form a thick homogeneous paste. Seal in an airtight container (e.g. a corrosion-resistant tin or a polythene bag) for 24 hours before testing. Mixing should be carried out on a glass plate with two palette knives. The required 24 hour maturing period may be shortened for soils with low clay contents. If only a few particles larger than 425 µm are present, these can be removed by fingers or with tweezers during mixing. If coarse particles are present determine their mass and the mass of the sample used. These weighings enable the approximate proportion of coarse material to be reported if required.

3.2.2.2

Wet preparation method. This is the preferred method for soil containing coarse particles, and should be used for all such soils that are sensitive to the effects of drying. Procedure 1. Take a representative specimen that will give at least 350 g passing a 425 µm sieve, and weigh it (m grams). This quantity should be sufficient for a liquid limit and a plastic limit test. Weighings should be carried out to an accuracy of within 0.01 g. 2. Take another representative sample for determination of moisture content (w %). Calculate and record the mass of dry soil in the test sample (mD ) from the equation:

mD =

100m 100 + w

3. Cut up the weighed sample in a beaker and just cover with distilled water. Stir to form a slurry. Do not use a dispersant. 4. Pour the slurry through a 2 mm sieve nested on a 425 µm sieve. Use the minimum amount of distilled water to wash clean the particles retained on both sieves. Continue until the water passing the 425 µm sieve is virtually clear. Collect all the washings. 5. Dry (at 1050C to 1100C) and weigh the retained material (mR grams) to an accuracy of within 0.01 g. 6. Allow the collected wash water to stand undisturbed, and pour or siphon off any clear water. A settling time of several hours may be required. It is important no to lose any soil particles during the siphoning procedure (see Note).

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7. Allow the suspension to partially dry in warm air, or in an oven at not more than 500C, or by filtration under vacuum or pressure, until it forms a stiff paste. But prevent local drying at the surface or edges, by repeated stirring. Note 1.

A suitable consistency for the paste corresponds to not less than 50 blows of the Casagrande apparatus.

Note 2.

When using this method, care should be taken with samples containing soluble salts. These samples should be allowed to dry by evaporation only, and not by siphoning or pouring off excess water.

3.2.2.3

Dry preparation method. If the use of a dry preparation method is unavoidable then the procedure should be followed as shown schematically in Figure 3.2.1.

3.2.3

Liquid limit test (Casagrande method) 1.

Apparatus a) b) c) d) e)

2.

Equipment for the determination of moisture content (weighing to 0.01 g). Soil mixing equipment (glass plate, spatulas, distilled water). Timer clock. Casagrande liquid limit device (Figure 3.2.2). Grooving tool and height gauge (Figure 3.2.3).

Calibration of apparatus The height of the underneath of the cup when fully lifted should be such that the 10 mm gauge will just pass between it and the base. Some grooving tools incorporate a block of the correct thickness. The locking nuts must be adjusted to maintain the correct height of drop. The device should be checked to make sure that the cup falls freely, that there is no side play in the cup, that the screws are tight, that the cup and base are not worn and that the blow counter works correctly and is set to zero. Details of the liquid limit device and how the cup fall is set are shown in Figure 3.2.4. The dimensions of the grooving tool are important and a reference (unused) tool should be available to check the tool being used against. When the tip of the tool being used becomes worn to a width of 3 mm it should be re-ground to the correct dimensions.

3.

Test Procedure a) Mix about 300 g of the prepared soil (after 24 hours maturing) with a little distilled water if necessary, using two spatulas, for at least 10 minutes. At this point the first blow count should be about 50 blows. If a plastic limit test is required it is convenient to set aside a portion of soil for this purpose. b) With the cup resting on the base, press soil into the cup being careful to avoid trapping air. Form a smooth level surface parallel to the base giving a maximum thickness of 10 mm (see Figure 3.2.5). c) Beginning at the hinge, and with the chamfered edge of the tool facing the direction of movement, make a smooth groove with a firm stroke of the grooving tool, dividing the sample into two equal parts. The tip of the grooving tool should lightly scrape the inside of the bowl, but do not press hard.

When using the tool, apply a circular motion so that it is always normal to the surface of the cup (see Figure 3.2.5).

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locking screw

locknut

pivot adjusting screw cam follower 10 mm

cup

direction or rotation

base handle a)

b)

Figure 3.2.4

a) The parts of the Casagrande device. b) The fully raised cup set to the specified height.

position of grooving tool

level surface

2

3

when cutting

thickness 10 mm

Figure 3.2.5

1

a) Soil placed in Casagrande bow

b) Use of the grooving tool

d) Rotate the handle at a speed of two turns per second – check with a seconds timer. Stop turning when the bottom of the groove closes along a continuous length of 13 mm (use the back of the grooving tool as a gauge). Record the number of blows. e) Add a little more soil from the mixture on the glass plate to the cup and mix in the cup. Repeat stages (b) to (d) stated above until two consecutive runs give the same number of blows for closer. Record the number of blows. f) Remove a portion of about 10 g of the soil adjacent to the closed gap with a clean spatula, transfer to a weighed container and fit the lid immediately. Record the container number and determine the moisture content. g) Repeat steps (b) to (f) stated above after adding increments of distilled water, mixing the water well in. At least two determinations should give more than 25 blows, and two less than 25, in the range of about 10 to 50 blows. Do not add dry soil to the soil paste. Protect the soil on the glass plate from drying out at all times. Each time the soil is removed from the cup for the addition of water, wash and dry the cup and grooving tool.

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4.

Standard Test Procedures

Calculation and Expression of Results After determining the moisture contents plot each moisture content against the number of blows on the printed test sheet. A line of best fit is drawn through the plotted points. This is called the ‘flow curve’. The liquid limit is defined as the percentage moisture content that corresponds to 25 blows as determined from where the ordinate at 25 blows intersects the flow curve. Record this value of moisture content to the nearest 0.1%. An example is given on the attached test sheet (see Form 3.2.1)

5.

Report The full report will include the sample details, method of preparation of the sample and the percentage passing the 425 µm sieve. The operator should sign and date the test form.

3.2.4

Plastic limit test 1.

Apparatus a) b) c) d)

2.

Equipment for the determination of moisture content (weighing to 0.01 g). Soil mixing equipment (glass plate, spatulas, distilled water). Smooth glass plate free from scratches, for rolling threads on. A length of rod, 3 mm in diameter and about 100 mm long.

Test Procedure a) Prepare and mature the test sample using wet or dry preparation method or take the sample previously set aside from the liquid limit test. b) Take about 20 g of the soil and allow it to lose moisture until it is plastic enough to be shaped into a ball without sticking to the fingers. Mould into a ball between the fingers and roll between the palms of the hands until slight cracks appear on the surface. Moulding and kneading is necessary throughout the test to preserve a uniform distribution of moisture and to prevent excessive drying of the surface only. c) Divide the sample into two roughly equal portions and carry out a separate test on each portion. d) Divide the first portion into four pieces. Mould one piece into a cylinder about 6 mm diameter between the first finger and thumb. e) Roll the cylinder under the fingers of one hand on a smooth glass surface, applying enough pressure to reduce the diameter to about 3 mm in about 5 to 10 complete forward and backward movements. Maintain a uniform pressure. Do not reduce pressure as the 3 mm diameter is approached. Use a metal rod of 3 mm diameter to judge the thread diameter. f) Pick up the soil thread, mould further and repeat the above. Repeat until the thread shears both longitudinally and transversely at a diameter of 3mm. Crumbling may consist of one of the forms shown in Figure 3.2.6 depending on the nature of the soil. g) Crumbling can usually be felt by the fingers. The crumbling condition must be achieved, even if greater than 3 mm diameter. If smooth threads of 3 mm diameter (like noodles) are formed, the soil is not dry enough, as illustrated in Figure 3.2.5. The first crumbling point is the plastic limit, do not attempt to continue reforming and rolling beyond this point.

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i) ii) iii) iv)

v)

Standard Test Procedures

Shearing and cracking both longitudinally and transversely. Falling apart in small pieces. Forming an outside tubular layer which splits at both ends. Breaking into barrel-shaped pieces. Heavy clay requires considerable pressure to reduce the diameter to 3 mm. No crumbling – soil too wet (like noodles).

Figure 3.2.6

3 mm

Some forms of crumbling in the plastic limit test

h) Gather the crumbled soil quickly, place in a small weighed container, and fit the lid immediately. Repeat the above process on second, third and fourth pieces of soil and place all fragments in the same container. Weigh it as soon as possible. i) Carry out the same operations on four pieces from the second portion, placing the fragments in a second container, and weigh. 3.

Calculation and Expression of Results Dry the specimens at 1050C – 1100C, weigh and calculate the moisture contents to the nearest 0.1%. If the two values differ by more than 0.5% moisture content repeat the whole test on another portion of soil. Otherwise, the average of the two values is the plastic limit. If it is not possible to determine the plastic limit this fact should be reported.

4.

Report The plastic limit is reported to the nearest whole number. The test sheet must be completed in full to give sample details, method of preparation and the percentage of material passing the 425 µm sieve. The test sheet should be signed and dated by the test operator. An example of a completed test sheet is attached (Form 3.2.1).

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3.2.5

Standard Test Procedures

Determination of the plasticity index 1.

Procedure The Procedure is a simple calculation and requires the determination of the liquid and plastic limits for the soil. The Casagrande method is to be used to determine the liquid limit. The plasticity index of a soil is the numerical difference between the liquid limit and the plastic limit: PI = LL – PL

2.

Report The plasticity index is reported to the nearest whole number. If both the liquid and plastic limits cannot be determined the soil is described as non-plastic (NP). Two special cases may be found. If it is possible to determine the liquid limit but not the plastic limit, the soil is reported as non-plastic. If the plastic limit is found to be equal to or greater than the liquid limit (as with some highly micaceous soils), the sample is also reported as non-plastic.

Determination of linear shrinkage 1.

Apparatus a) A drying oven capable of operating at 600C – 650C and 1050C – 1100C. b) Soil mixing equipment (glass plate, spatulas, distilled water). c) Vernier calipers measuring up to 150 mm and reading to 0.1 mm. Alternatively, a steel rule graduated to 0.5 mm. d) Silicone grease or petroleum jelly. e) Evaporating dish (approx. 150 mm ∅). f) Moulds made of brass or other non-corrodible material. They shall be semicircular in cross section with an internal radius of 12.5 ± 0.5 mm and 140 mm long, with square end pieces attached as supports which also serve to confine the soil (see Figure 3.2.7).

20

3 40

3.2.6

R=12.5± 0.5

140± 1.0 6 All dimensions are in millimetres.

Figure 3.2.7 2.

Mould for linear shrinkage test

Test Procedure a) Preparation of apparatus. Clean the mould thoroughly and apply a thin film of silicone grease or petroleum jelly to its inner faces to prevent the soil adhering to the mould.

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b) Prepare and mature the test sample using wet or dry preparation method. Place a sample of about 150 g on the flat glass plate or in the evaporating dish. c) Add distilled water if necessary and mix thoroughly using the palette knives until the mass becomes a smooth homogeneous paste with a moisture content at about the liquid limit of the soil. Note. The required consistency will require about 25 bumps of the Casagrande apparatus. This moisture content is not critical to within a few percent. d) Place the soil / water mixture in the mould such that it is slightly proud of sides of the mould. Gently jar the mould to any air pockets in the mixture. e) Level the soil along the top of the mould with the palette knife and remove all soil adhering to the rim of the mould by wiping with a damp cloth. f) Place the mould where the soil / water can air-dry slowly in a position free from draughts until the soil has shrunk away from the walls of the mould. Then complete the drying, first at a temperature not exceeding 65 0C until shrinkage has largely ceased, and then at 1050C to 1100C to complete the drying. g) Cool the mould and soil and measure the mean length of the soil bar. If the specimen has become curved during drying, remove it carefully from the mould and measure the lengths of the top and bottom surfaces. The mean of these two lengths shall be taken as the length of the oven dry specimen. Note. Should a specimen crack badly, or break, such that measurement is difficult, the test should be repeated at a slower drying rate. 3.

Calculation and expression of results Calculate the linear shrinkage of the soil as a percentage of the original length of the specimen, LO (in mm), from the equation:



Percentage of linear shrinkage =  1 -



LD   100 LO 

Where, L D is the length of the oven-dry specimen (in mm). 4.

Report The linear shrinkage is reported to the nearest whole percentage. The test sheet (see Form 3.2.2) must be completed in full to give sample details, method of preparation and the percentage of material passing the 425 µm sieve. The test sheet should be signed and dated by the test operator. An example of the calculation is shown in Form 3.2.2.

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3.3

Particle Size Distribution

3.3.1

Introduction. The determination of the particle size distribution of soil is an important part of classification. The particle size distribution of a granular material such as road base or a concrete aggregate, is an essential guide to the stability of the material for use in the works, as the engineering properties of the material are strongly dependent upon the grading. In the case of fine grained cohesive soils which contain only a small percentage of sand and silt, it is not generally necessary to carry out a particle size distribution, as the Atterberg limits will provide sufficient guide to the properties of the soil. Particle size distribution can be done by dry sieving or wet sieving. Wet sieving may be used on any material and is more accurate than dry sieving but takes slightly longer to perform.

3.3.2

General requirements

3.3.2.1

Sample mass. Mass of soil sample required for sieving is shown in the Table 3.3.1. Table 3.3.1 Mass of soil sample for sieving Maximum size of material present in substantial proportion (more than 10%) Test sieve aperture mm 63 50 37.5 28 20 14 10 6.3 5 3.35 2 or smaller

3.3.2.2

kg 50 35 15 6 2 1 0.5 0.2 0.2 0.15 0.1

Accuracy of weighing. The accuracy of weighing required depends on the size of the sample or sub-sample and the following values should be used.

Fine grained soils Medium grained soils Coarse grained soils 3.3.2.3

Minimum mass of sample to be taken for sieving

Minimum accuracy of weighing 0.1 gms 1 gms 10 gms

System of sieve sizes. Different systems of sieves are used at present time. Anyone of these sieve systems may be used in the test, provided all sieves in one set are of the same system. Slight differences in aperture (mesh) sizes can easily be accounted for when the results are plotted on a logarithmic grading chart. Sieves designation and their sizes are shown in the Table 3.3.2.

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Table 3.3.2 Sieves designation and their sizes BS sieve aperture size

Sieves to ASTM D422 Nearest designation Aperture size 75 mm 3 inch 75 mm 63 21/2 inch 63.5 50 2 inch 50.8 37.5 11/2 inch 38.1 28 1 inch 25.4 3 20 /4 inch 19.05 14 3 10 /8 inch 9.52 6.3 5 No. 4 4.75 3.35 No. 6 3.35 No. 8 2.36 2 No. 10 2.00 1.18 No. 16 1.18 No. 20 850 µm No. 30 600 µm 600 No. 40 425 425 No. 50 300 300 No. 60 250 No. 70 212 212 No. 100 150 150 No. 140 106 No. 200 75 75 No. 230 63 63 * Sieves marked with * have been proposed as an International (ISO) Standard. It is recommended to include, if possible, these sieves in all sieve analysis data or reports. 3.3.2.4

Care and use of sieves a) If too much material is placed on a sieve at any one time, some of the fine material will not reach the mesh and will be retained on the sieve, thus giving errors. It is therefore important to ensure the sieves are never overloaded. Table 3.3.3 gives the maximum mass of material to be retained on each sieve at the completion of sieving.

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Table 3.3.3 Maximum mass of material to be retained on each sieve at the Completion of sieving Test sieve Aperture size

Maximum mass on sieve of diameter

mm 50 37.5 28 20 14 10 6.3 5 3.35 2 1.18 µm 600 425 300 212 150 75

(3/8 in) (1/4 in) (4) (6) (10) (16)

450 mm kg 10 8 6 4 3 2 1.5 1.0 -

300 mm kg 4.5 3.5 2.5 2.0 1.5 1.0 0.75 0.5 -

200 mm g 1000* 500* 350* 300 200 100

(30) (40) (50) (70) (100) (200)

-

-

75 75 50 50 40 30

(2 in) (11/2 in) (3/4 in)

Note 1. Numbers in brackets indicate equivalent ASTM sieve sizes or numbers. Note 2. *It may be more appropriate to use a larger diameter sieve for material of this size, depending on the size of the fraction in the sample. 1 mm = 1000 microns (1000 µm) b) The fine sieves must not be overloaded, because this not only leads to inaccuracy but also reduces the life of the sieve. c) It is very difficult to prevent overloading, when using mechanical sieve shakers and mechanical sieve shakers are not recommended except for coarse grained materials. d) Particles larger than 20 mm may be placed through the sieve by hand, but must not be forced through. All smaller sizes must be shaken through the sieves. e) The sieves must be kept clean by brushing with a brass or camel hair brush and washing through all sieving. Fine sieves should be inspected for holes in the mesh before use. Care in the use of sieves and prevention of overloading will lead to longer lives. 3.3.3

Wet sieving method

3.3.3.1

Scope. When a perceptible amount of clay or silt or if fine particles are found connected with the larger particles, then wet sieving must always be used.

3.3.3.2

Apparatus. (1)

A typical range of aperture or mesh sizes would be : 75 mm, 63 mm, 50 mm, 37.5 mm, 28 mm, 20 mm, 14 mm, 10 mm, 6.3 mm, 5 mm, 3.35 mm, 2 mm, 1.18 mm, 600 ± = µm, 425 µm, 300 µm, 212 µm, 150 µm, 75 µm. Lids and receives of appropriate size are required.

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Notes a) The aperture sizes to be used will vary from sample to sample. Only the necessary aperture sizes should be used, except that, for convenience or to prevent overloading, additional sieves may be used so that the requirements of Table 3.3.3 are complied with. b) The defining size separating fine sand and silt grades is 60 µm. The aperture size normally found closest to this is 63 µm. However, in practice the 75 µm sieve is more commonly used because it is more robust and less time-consuming to use. This standard suggests the continued use of the 75 µm sieve as the washing sieve. Some manufacturers’ offer a special ‘washing’ sieve which is of 200 mm diameter and 200 mm deep with a 75 µm mesh. c) It can be useful to have two sets of sieves, one for the wet sieving and one for the dry sieving processes. (2) (3) (4) (5) (6) (7) (8) (9) (10) (11) (12) (13) (14) (15) 3.3.3.3

A balance readable to 1.0 g. A balance readable to 0.1 g. Sample divider(s) of appropriate slot width (riffle boxes). Thermostatically controlled drying oven capable of maintaining 105±50C. An evaporating dish about 150 mm diameter. A corrosion-resistant tray, a convenient size being about 300 mm square and 40 mm deep. Two or more large corrosion-resistant metal or plastics watertight trays with sides about 80 mm deep, or a bucket of about 12 L capacity. A scoop. Sieve brushes, and a wire brush or similar brush. Sodium hexametaphosphate (dispersing agent). A quantity of rubber tubing about 6 mm bore. A sprayer such as a small watering can use. Appropriate number of enamel or porcelain dishes. A mechanical sieve shaker (optional).

Test procedure (1)

(2) (3)

The representative riffled sample is oven-dried at 105±50C to give a minimum mass complying with Table 3.3.3. If separation of the silt and clay fractions is to be carried out, or if the particle size distribution is to be extended below 75 µm, a second riffled sample shall be obtained for a fine analysis. Weigh the cooled oven-dried sample to 0.1% of its total mass (m1). Sieve the sample through all required sieve sizes of 20 mm size and larger. The mass retained is recorded on the test sheet in each case. Any fine particles adhering to the retained material should be removed with a stiff brush during sieving. The brushing should be done carefully to avoid losing material. Take care with soft materials to ensure that the brushing does not remove parts of the large particles. Note.

If adhering fine material cannot be removed easily by brushing, the following procedure may be followed.

a) Remove the fine material from the coarse particles by washing. b) Dry and weigh the coarse particles to 0.1% of their mass. c) Dry the washings, add them to the material passing the 20 mm test sieve, and mix thoroughly. (4)

The mass passing the 20 mm sieve is determined to 0.1% of its total mass (m2) and the sample is then divided (riffled) so that about 2 kg of material remains. The mass of this sub-sample is then determined to 0.1% of its total mass (m3).

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(6) (7)

The sample shall then be placed in a large tray, enamel or porcelain bowl or in the bucket, and covered with water. If the soil is cohesive add sodium hexametaphosphate first at the rate of 2 grams per litre of water and stir until dissolved. Sodium hexametaphosphate is a dispersing agent and helps to prevent fine particles sticking together. The sample should be soaked for a minimum of 1 hour and frequent stirring should be given during this time. The sample is then washed through the 75 µm (No. 200) sieve with a 2 mm mesh sieve placed on top of it to protect it. Washing is most easily done by the decantation method. In this method, water is slowly added to the bowl or tray and the contents are vigorously stirred. Allow the contents to settle for a few seconds before pouring. The excess water is decanted carefully over the side of the bowl through the 2 mm sieve and into the 75 µm sieve, making sure all the water passes through the 75 µm sieve before running to waste. This process is continued until the water leaving the bowl is perfectly clear and all clay and silt particles have been washed through the sieve. Make sure that the fine sieve does not become overloaded, either by retained soil or by water. Note.

(8) (9) (10)

(12)

(13)

During this process DO NOT rub the material on the 75 µm sieve with your fingers or otherwise. This is likely to damage the sieve and give errors in the test results.

On completion of washing place the washed sample in a tray or evaporating dish and place in the oven to be dried at 105±50C. After drying and cooling, weigh the sample to 0.1% of its total mass before commencing sieving (m4). Fit the largest size test sieve appropriate to the maximum size of material present to the receiver and place the sample on the sieve. Fit the lid to the sieve. Note.

(11)

Standard Test Procedures

If the sieve and receiver assembly is not too heavy to handle, several sieves, in order of size, may be fitted together and used at the same time.

Agitate the test sieve so that the sample rolls about in an irregular motion over the sieve. Particles may be placed by hand to see if they will fall through but they must not be pushed through. Make sure that only individual particles are retained. Weigh the amount retained on the test sieve to 0.1% of its total mass. Keep each fraction separate so that check weighings may be carried out at a later date if required. Transfer the material retained in the receiver to a tray and fit the receiver to the next largest sized sieve. Place the contents of the tray on the sieve and repeat the operation in (11). Be careful not to lose fine material by using a brush to clean the sieve mesh and the receiver. Use of the lid helps to reduce loss of fines. Sieving is then continued through progressively smaller sizes until the sample has been passed through the 6.3 mm sieve. The mass of soil passing the 6.3 mm sieve is determined to 0.1% of its total mass (m5). If the mass of material passing the 6.3 mm sieve is too big (i.e. substantially more than 150 grams), the actual mass passing should be recorded and the sample divided again by riffling to give a reduced sample of about 100 to 150 grams. The mass of the sub-sample is then determined to 0.1% of its total mass (m6). Sieving is now continued through the remaining sieve sizes. The mass retained on each sieve is recorded to 0.1% of its total mass. The mass passing the 75 µm sieve should be determined (ME). This mass will be very small if washing has been carried out thoroughly. If any of the sieves are in danger of becoming overloaded the sample should be sieved a little at a time and the material MAY 2001

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retained each time placed in a clean porcelain or enamel dish ready for weighing. Note 1. If a mechanical sieve shaker is available this may be used to perform the sieving operation provided that all the sieves are the same diameter and that they are not overloaded during the process. A minimum shaking time of 10 minutes is required. 2. Sample dividing is carried out to prevent having to sieve large amounts of material through the fine sieve sizes with the consequent risk of overloading. If only one or two fine sieves are to be used it may be quicker not to divide the sample and to sieve the total sample through these sieves a little at a time. If 20 mm or 6.3 mm sieves are not being used, dividing may be carried out for convenience at the sieve closest to 20 mm and 6.3 mm. 3.3.3.4

Calculation and expression of results (1)

Summation Check. The first stage in the calculation is to check that all the weights retained add up to those of the original sample or sub-samples making due allowance for the weights passing the smallest sieve and any sieve where the sample has been divided. If these weights are not close to the correct total (i.e. within 1%) it is then possible to re-weigh the containers and to locate any errors before the sample is discarded. If this check is left until a later date it will be necessary to repeat the complete test if any error is found.

(2)

Calculation of correction factors a) It is necessary to calculate the correction or riffle factor for the first sieve size where the sample has been divided: Correction factor, f1 =

Original mass passing sieve size Mass of sub - sample after dividing =

m2 m3

b) The correction factor is then applied to each sieve smaller than the one where the sample was divided until the sample is again sub-divided. Where a second sub-division takes place the new correction factor is given by : New correction factor, f2 = f1 x

=

Original mass passing sieve size Mass of sub - sample after dividing

m2 m x 5 m3 m6

c) The adjusted mass retained MAR is then obtained for each sieve size by multiplying the actual mass retained MR by the respective correction factor. Adjusted mass retained MAR = f x MR d) The percentage retained is obtained by dividing the adjusted weight retained by the total sample weight and expressing the result as a percentage: MAY 2001

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M

% Retained =

AR x 100% m1

e) The cumulative percentage passing is then obtained by deducting the percentage retained on the largest sieve size from 100% and then deducting the percentage retained for each smaller size from the previous cumulative percentage. f) The percentages retained on each sieve and cumulative percentages passing each sieve should be calculated to the nearest 0.1%. The values can be expressed in tabular form and / or in graphical form. An example of a sieve test calculation is shown in Form 3.3.1, and the results are shown plotted on a semi-logarithmic chart in Form 3.3.3. 3.3.3.5

Report. The report should include the tabulated results of the test calculated as cumulative percentages passing to the nearest whole number. The results should be plotted on a semi-logarithmically form (see Form 3.3.3). The method of test should be reported and the operator should sign and date the test sheet.

3.3.4

Dry sieving method

3.3.4.1

Scope. This method covers the quantitative determination of the particle size distribution of a soil down to the fine sand size. It should only be used with clean, free running or washed sands and gravels.

3.3.4.2

Apparatus. The apparatus used in the wet sieving method are also used in the dry sieving method.

3.3.4.3

Test procedure

3.3.4.4

(1) Oven dry the riffled sample at 105±50C to give a specified minimum mass and then cool and weigh to 0.1% of its total mass (m1). (2) Sieve the sample through all required sieve sizes of 20 mm size and larger. The mass retained is recorded on the test sheet in each case. (3) The mass passing the 20 mm sieve is determined to 0.1% of its total mass (m2) and the sample is then divided so that about 2 kg of material remains. The mass of this sub-sample is then determined to 0.1% of its total mass (m3). (4) Then sieve the dried and weighed sample through the largest sieve size required and the mass of the sample retained is recorded on the data sheet. Use of the lid will help to reduce loss of fines. (5) Sieving is then continued through progressively smaller sizes until the sample has been passed through the 6.3 mm sieve (m4). If the weight of the material passing the 6.3 mm sieve is too big (more than 150 gms). The actual mass passing should be recorded and the sample is divided to give a reduced sample of about 100 to 150 gms. The mass of the sub-sample is then determined to 0.1% of its total mass (m5). (6) Sieving is now continued through the remaining sieve sizes. The mass retained on each sieve is recorded to 0.1% of its total mass. The mass passing the 75 µm sieve should be determined (ME). If any of the sieves are in danger of becoming overloaded the sample should be sieved a little at a time and the material retained each time is placed in a clean porcelain or enamel dish ready for weighing. If a mechanical sieve shaker is used, a minimum shaking time of 10 minutes is required. Calculation and expression of results. The procedure is the same as of wet sieving method (section 3.3.3.4). An example of a sieve test calculation is shown in Form 3.3.2. MAY 2001

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Form 3.3.1

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Standard Test Procedures Form 3.3.2

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Standard Test Procedures Form 3.3.3

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3.4

Determination of Organic Content

3.4.1

Scope. The “Loss on Ignition”: method for the determination of organic content is most applicable to those materials identified as peats, organic mucks, and soils containing relatively undecayed or undecomposed vegetative matter or fresh plant materials such as wood, roots, grass or carbonaceous materials such as lignite, coal, etc. This method determines the quantitative oxidation of organic matter in these materials and gives a valid estimate of organic content.

3.4.2

Apparatus

3.4.2.1

3.4.2.5 3.4.2.6 3.4.2.7

Oven-Drying oven capable of maintaining temperatures of 110±5 C (230±9 F). Gravity, instead of blower convection may be necessary when drying lightweight material. Balance-(to required sensitivity) Muffle Furnace-The furnace shall be capable of maintaining a continuous temperature of 445±10 C (833±18 F) and have a combustion chamber capable of accommodating the designated container and sample. Pyrometer recorder shall indicate temperature while in use. Crucibles or Evaporating Dishes-High silica, alundum, porcelain or nickel crucibles of 30 to 50 ml capacity or Coors porcelain evaporating dishes approximately 100 mm top diameter. Desiccator-A desiccator of sufficient size containing an effective dessicant. Containers-Suitable rustproof metal, porcelain, glass or plastic coated containers. Miscellaneous Supplies-Asbestos gloves, tongs, spatulas, etc.

3.4.3

Sample preparation

3.4.3.1

A representative sample weighing at least 100 grams shall be taken from the thoroughly mixed portion of the material passing the 2.00 mm (No. 10) sieve. Place the sample in a container and dry in the oven at 110±5 C (230±9 F) to constant weight. Remove the sample from the oven, place in the desiccator and allow to cool.

3.4.2.2 3.4.2.3

3.4.2.4

3.4.3.2

Note 1.

This sample can be allowed to remain in the oven until ready to proceed with the remainder of the test.

3.4.4

Ignition procedure

3.4.4.1

Select a sample weighing approximately 10 to 40 grams, place into tared crucibles or porcelain evaporating dishes and weigh to the nearest 0.01 gram. Note 2.

3.4.4.2

3.4.4.3

Sample weights for lightweight materials such as peat may be less than 10 grams but should be of sufficient amount to fill the crucible to at least ¾ depth. A cover may initially be required over the crucible during initial phase of ignition to decrease possibility sample being “blow out” from the container.

Place the crucible or dish containing the sample into the muffle furnace for six hours at a temperature of 445±10 C. Remove the sample from the furnace, place into the desiccator and allow to cool. Remove the cooled sample from the desiccator and weigh to the nearest 0.01 gram.

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3.4.5

Calculation

3.4.5.1

The organic content shall be expressed as a percentage of the mass of the oven dried soil and shall be calculated as follows:

Percent Organic Matter =

A - B x 100 A - C

where: A = Weight of crucible or evaporating dish and oven dried soil, before ignition B = Weight of crucible or evaporating dish and dried soil, after ignition. C = Weight of crucible or evaporating dish, to the nearest 0.01 gram. 3.4.5.2

Calculate the percentage of organic content to the nearest 0.1 percent.

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3.5

Standard Description and Classifications

3.5.1

Scope. The description of soils is an important stage in the process of sampling and testing of soils for civil engineering purposes. In order to be readily understood, the descriptions should be carried out in a standard and methodical manner. The terms “soil description” and “soil classification” are sometimes confused. Although interconnected, the use of the two terms can be separated and definitions are given in 3.5.2 below. Given individually, both a description and a classification may be useful. When used together, a greater understanding of the likely engineering characteristics of the soil can be obtained.

3.5.2

Definitions

3.5.2.1

Soil description. A full description gives detailed information on the grading, plasticity, colour, moisture and particle characteristics of a soil, as well as on the fabric and strength condition in which it occurs in a sample, borehole or exposure.

3.5.2.2

Soil classification. A classification places a soil in a limited number of groups on the basis of grading and plasticity of a disturbed sample. These characteristics are independent of the particular condition in which a soil occurs, and disregard the influence of the structure, including fabric, of the soil mass.

3.5.3

Soil groups and field identification methods

3.5.3.1

Coarse soils (over 65% sand and gravel sizes) (1) (2) (3) (4) (5)

3.5.3.2

Sands and gravels are coarse soils. Cobbles and boulders are very coarse soils. Coarse soils are visible to the naked eye. A small hand-lens may be useful for the examination of finer sands or the surface of larger particles. If required, a set of sieves may be used to determine approximate proportions (as judged by eye) of gravel sizes, e.g. 60 mm 20 mm, 6 mm and 2 mm. Sands, particularly those mixed with clay or silt fines, may usefully be examined mixed with a little water in the palm of the hand or in a small enamel bowl. Observations on the ease of excavation will be helpful. Whether the soil can be easily excavated with a spade, or requires a pickaxe or hoe for excavation will determine the consistency aspect of its description. If may also be useful to have available a wooden peg approximately 50 mm square with one sharpened end. The ease with which this can be hammered into the ground is an indication of the density of the soil.

Fine soils (over 35% silt and clay sizes) (1)

(2)

(3)

Fine soils require to be examined by hand to obtain an adequate description, preferably with the aid of a plastic was bottle containing water. This should readily aid the distinction of the soil between a clay and a silt. Silts can be detected by carrying out a test for dilatancy. A small sample of soil is mixed with water so that it is soft but not sticky, and held in the palm of the hand. The edge of the hand is jarred gently with the other hand and the sample observed. The appearance of a shiny film of water on the surface indicates dilatancy. Squeeze the soil by pressing with the fingers, and the surface will go dull again as the sample stiffens and finally crumbles. These reactions indicate the presence of predominantly silt-sized material or very fine sand, provided that the amount of moisture is not excessive. Moist silt is difficult to roll into threads since it crumbles easily. The most significant properties of clay are its cohesion and plasticity. If when pressed together in the hands at a suitable moisture content the particles stick MAY 2001

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(4)

(5)

3.5.3.3

Standard Test Procedures

together in a relatively firm mass, the soil shows cohesion. If it can be deformed without rupture (i.e. without losing its cohesion), it shows plasticity. Clay dries more slowly than silt and sticks to the fingers; it cannot be brushed off dry. It has a smooth feel, and shows a greasy appearance when cut with a blade. Dry lumps can be broken, sometimes with difficulty, between the fingers, but cannot be powdered. A lump placed in water remains intact for a considerable time. Clay does not exhibit dilatancy. Lumps shrink appreciably on drying, and show cracks which are the more pronounced the higher the plasticity of the clay. At a moisture content within the plastic range, clay can easily be rolled into threads of 3 mm diameter (as in the plastic limit test) which for a time can support their own weight. Threads of high - plasticity clay are quite tough; those of low-plasticity clay are softer and more crumbly. If it is important to know the composition of fine soils accurately then a particle size distribution test should be carried out subsequently in the laboratory.

Organic soils (1) (2)

Organic soils may be organic clay, silt or sand, or may be a form of peat. Examination in the field will be by visual and manual inspection in the same way as for other soils, paying particular attention to compactness and structure. Peat often has a distinctive smell and low bulk density. Laboratory testing will be necessary to accurately determine relative proportions of organic and mineral matter.

3.5.4

Methodology of description

3.5.4.1

General. In describing a soil, attention is given to a number of different aspects in a methodical manner, determined using the techniques outlined in Section 3.5.3 above. These aspects are summarised as follows, and are used in the order given, as far as is practicable. Descriptions made in the field may require to be modified subsequently in the light of the results of laboratory tests, or when better facilities are available for inspection. The preferred order of description is conveniently remembered as MCCSSO : a) b) c) d) e) f)

Moisture condition Consistency (compactness/strength) Colour Structure Soil type Origin

Examples of test forms 3.5.1 and 3.5.2 for use in the field are included at the end of this section. The test forms refer to the various elements of description as explained in detail in 3.5.4.2 below. 3.5.4.2

Descriptive terms (1)

Moisture condition. The moisture condition of the sample can be indicted by use of the following terms:

a) b)

Dry Slightly moist

: :

c) d) e)

Moist Very moist Wet

: : :

Soil will require the addition of water to attain the optimum moisture content for compaction (OMC). Near OMC for compaction Will require drying to achieve OMC From below water table.

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(2)

Standard Test Procedures

Consistency. Consistency or compactness/strength of the soil is described using different terms for different soil types. These terms and the field tests for them are given in Tables 3.5.1 to 3.5.5. Table 3.5.1 Very coarse soils -boulders and cobbles Term Field test Loose By inspection of voids and Dense particle packing Table 3.5.2 Coarse soils - gravels and sands Term Field test Very loose Crumbles very easily when scraped with geological pick. Loose Can be excavated with a spade; 50 mm wooden peg can be easily driven. Medium dense Between loose and dense. Dense Requires pickaxe or hoe for excavation; 50 mm wooden peg hard to drive. Slightly cemented For sands. Visual examination; pickaxe or hoe removes soil in lumps which can be abraded. Table 3.5.3 Fine soils - silts Term

Field test Easily moulded or crushed in the fingers. Can be moulded or crushed by strong pressure in the fingers. Exudes between fingers when squeezed in hand (like toothpaste).

Soft or loose Firm or dense Very soft

Table 3.5.4 Fine soils - clays Term Very soft Soft Firm Stiff Very stiff or hard

Field test Comes out between fingers (like toothpaste) when squeezes in hand. Moulded by light finger pressure. Can be moulded by strong finger pressure. Cannot be moulded by fingers. Can be indented by thumb. Can be indented by thumbnail.

Table 3.5.5 Organic soils Basic Soil Type Organic Clay, silt or sand

Term Firm Spongy

Field test Fibres already compressed together Very compressible and open structure

Peats Plastic

MAY 2001

Can be moulded in hand, and smears fingers.

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Chapter 3 Classification Tests (3)

Standard Test Procedures

Colour. The colour of soil samples should be assessed in a freshly excavated condition. This colour may be different from a dried sample, and from the sample mixed with water. Under some circumstances it may be important to know these differences. It is preferable to use a standard colour chart such as that developed by Munsell. If standard colour charts are not available, use colour descriptions which are readily understood, e.g. red, brown, green, yellow, white black, pink etc. These can be supplemented by the use of words like: light, dark etc. Soils can also be one colour mottled with another, or one colour blotched or veined with another.

(4)

Structure. The soil being sampled may have a distinct structure and if so this should be recorded in the description. Tables 3.4.6 to 3.4.10 present guidelines for the descriptive terms to be used. Table 3.5.6 Coarse and very coarse soils. Boulders, cobbles, gravels and sands Term Homogeneous Interstratified

Heterogeneous Weathered

Field identification Deposit consists essentially of one type. Alternating layers of varying types or with bands or lenses of other materials. Interval scale for bedding spacing may be used (see Table 3.5.7). A mixture of types. Particles may be weakened and may show concentric layering.

Table 3.5.7 Scale of bedding spacing (see Table 3.5.6) Term Very thickly bedded Thickly bedded Medium bedded Thinly bedded Very thinly bedded Thickly laminated Thinly laminated

Mean spacing, mm Over 2000 2000 to 600 600 to 200 200 to 60 60 to 20 20 to 6 Under 6

Table 3.5.8 Fine soils – silts and clays Term Fissured

Intact Homogeneous Interstratified Weathered Slicken sided

Field identification Break into polyhedral fragments along fissures. Interval scale for spacing of discontinuities may be used (see Table 3.5.9). No fissures or joints. Deposit consists essentially of one type. Alternating layers of varying types. Interval scale for thickness of layers may be used (see Table 3.5.7). Usually has crumb or columnar structure. Indicates the presence of fissures with polished or scratched surfaces.

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Chapter 3 Classification Tests

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Table 3.5.9 Scale of spacing of other discontinuities (see Table 3.5.8) Term Very widely spaced Widely spaced Medium spaced Closely spaced Very closely spaced Extremely closely spaced

Mean spacing, mm Over 2000 2000 to 600 600 to 200 200 to 60 60 to 20 under 20

Table 3.5.10 Organic soils – peats Term Fibrous Amorphous (form is lacking) (5)

Field identification Plant remains recognizable. Recognizable plant remains absent.

Soil type a) The basic soil type to be described, their limiting sizes and visual identification are given in Table 3.5.11. In the description the predominant soil type is written in capital letters, e.g. GRAVEL. Typical grading curves which would be obtained on well graded, uniformly graded and gap graded coarse soils are shown in Figure 3.5.1.

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Chapter 3 Classification Tests

Standard Test Procedures

Table 3.5.11 Soil types

Very Coarse soils

Basic soil type BOULDERS

Particle size, mm

Visual identification Only seen complete in pit or exposures.

200 COBBLES

Often difficult to recover from boreholes. 60 coarse

Easily visible to naked eye; particle shape can be described; grading can be described. 20

Coarse soils (over 65% sand and gravel sizes)

GRAVELS

medium

6

Well graded : wide range of grain sizes, well distributed. Poorly graded : not well graded. (May be uniform : size of most particles lies between narrow limits; or gap graded : an intermediate size of particle is markedly underrepresented.

fine 2 coarse SANDS

Visible to naked eye; very little or no cohesion when dry; grading can be described. 0.6

medium

0.2

Well graded : wide range of grain sizes, well distributed. Poorly graded : not well graded. (May be uniform : size of most particles lies between narrow limits; or gap graded : an intermediate size of particle is markedly underrepresented.

fine 0.06 SILTS

coarse

Organic soils

Fine soils (over 35% silt and clay sizes)

0.02

Only coarse silt barely visible to naked eye; exhibits little plasticity and marked dilatancy : slightly granular or silky to the touch. Disintegrates in water; lumps dry quickly; possess cohesion but can be powdered easily between fingers.

medium 0.006 fine 0.002 CLAYS

ORGANIC CLAY, SILT or SAND

varies

PEATS

varies

Dry lumps can be broken but not powdered between the fingers; they also disintegrate under water but more slowly than silt; smooth to the touch; exhibits plasticity but no dilatancy; sticks to the fingers and dries slowly; shrinks appreciably on drying usually showing cracks. Intermediate and high plasticity clays show these properties to a moderate and high degree, respectively. Descriptions should include an indication of plasticity if possible. Contains substantial amounts of organic vegetable matter. Predominantly plant remains usually dark brown or black in colour, often with distinctive smell; low bulk density.

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Chapter 3 Classification Tests

Standard Test Procedures

b) Many (most) soils exist as composite soil types, i.e. mixtures of basic soil types. Examples would be a slightly clayey GRAVEL, or a silty SAND. In these examples the clay and silt are secondary constituents. The secondary constituents are included in the description according to a set scale. This scale of proportions for secondary constituents for secondary constituents for coarse soils is set out in Table 3.5.12 and for fine soils in Table 3.5.13. Table 3.5.12 Scale of secondary constituents with coarse

soils

Term

% of clay

Remarks

or silt slightly clayey

GRAVEL or SAND

slightly silty - clayey

GRAVEL or

- silty

10.5

very clayey

GRAVEL or SAND

very silty Sandy GRAVEL Gravelly SAND

under 5

5 to 15

Percentage of clay

or silt has to be estimated in the field.

15 to 35

Sand or gravel and important second constituent of the coarse fraction

Note : For composite types described as: clayey : fines are plastic, cohesive: silty : fines non-plastic or of low plasticity Table 3.5.13 Scale of secondary constituents with fine soils Term sandy gravelly

% of sand or gravel

CLAY or SILT

35 to 65 (Assessed by eye)

- CLAY : SILT

under 35 (Assessed by eye)

c) Coarse and very coarse soils can be given a supplementary description for their shape and for the texture of their surface. Standard descriptive terms for shape are given in Table 3.5.14, and for texture in Table 3.5.15. Figure 3.5.2 shows typical shapes for descriptive purposes.

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Chapter 3 Classification Tests

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Chapter 3 Classification Tests

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Table 3.5.14 Angularity and form of coarse particles

Angularity

Term Angular Subangular Subrounded Rounded

Form

Equidimensional Flat (flaky) Elongated Flat and elongated Irregular

Remarks Possessing well-defined edges formed at the intersection of roughly planar faces. Corners slightly bevelled. All corners rounded off. Fully water-worn or completely shaped by attrition. All dimensions roughly equal. Having one dimension significantly smaller than the other two dimensions. Having one dimension significantly larger than the other two dimensions. See Figure 3.5.2. Naturally irregular, or partly shaped by attrition and having rounded edges.

Table 3.5.15 Surface texture of coarse soils Typical descriptive terms rough smooth honeycombed pitted glassy (6)

Origin. This part of the description consists of information on the geological formation, age and type of deposit. This information may not always be available to persons carrying out field descriptions but should be included where it is available. Examples of the kind of information to be included would be: a) b) c) d) e) f)

Girujan Clay Dihing Formation Tippam Group River deposit (alluvium) Beach deposit (littoral) Lake deposit (lacustrine)

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Chapter 3 Classification Tests 3.5.4.3

Standard Test Procedures

Examples (1)

Coarse soils An example of a completed test sheet for coarse soils is shown as Form 3.5.1. Two further examples of descriptions for coarse soils are given below: Example 1

Example 2

(a) Moisture condition :

damp

moist

(b) Consistency :

loose

dense

dark brown

yellow

homogeneous

+ thin lenses of soft

(c) Colour : (d) Structure :

grey silty CLAY (e) Soil Type :

sandy rounded smooth textured fine medium

Fine and medium (FM) SAND

and coarse (FMC) GRAVEL (f) Origin :

beach deposit

Recent Alluvium

Composite description for Example 1 : Damp loose dark brown homogeneous sandy smooth textured rounded fine medium and coarse GRAVEL. Beach Deposit. Composite description for Example 2 : Moist dense yellow fine and medium SAND with thin lenses of soft grey silty CLAY. (2)

Fine soils An example of a completed test sheet for fine soils is shown as Form 3.5.2. Two further examples of descriptions for fine soils are given below: Example 1

Example 2

(a) Moisture condition :

wet

dry

(b) Consistency :

soft

firm to stiff

blue-grey

grey mottled brown

(d) Structure :

+ closely spaced partings of firm brown SILT

widely fissured

(e) Soil Type :

sandy CLAY

silty CLAY

(c) Colour :

(high plasticity) (f) Origin :

Recent Alluvium

-

Composite description for Example 1 : Wet soft blue-grey sandy CLAY of high plasticity with closely spaced partings of firm brown SILT. Recent Alluvium. Composite description for Example 2 : Dry firm to stiff grey mottled brown widely fissured silty CLAY. MAY 2001

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Chapter 3 Classification Tests

3.5.4.4

Standard Test Procedures

Standard symbols. Soils descriptions carried out as part of a site investigation programme can be shown in borehole and trial pit records in the form of symbols. Standard symbols for soils are presented in Figure 3.5.3.

Made ground

Boulders and cabbles

Gravel

Sand

Silt

Clay

Peat Note. Comsite soil types will be signified by combined symbols, e.g. Silty sand

Figure 3.5.3 Note.

Standard soils symbols

Made ground means a soil which is artificially placed, e.g. in embankment.

An example of how these symbols might be used in a borrow area investigation is shown in Figure 3.5.4. Representing soil types in this manner should enable a clearer picture to be obtained of the soils in the area being investigated. Such a representation should be accompanied by a scaled plan to enable available quantities to be calculated. A second example of the use of standard symbols is shown in Figure 3.5.5. This is taken from a site investigation report for a road project.

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Chapter 3 Classification Tests

Standard Test Procedures

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Chapter 3 Classification Tests

Standard Test Procedures

MAY 2001

Page 3.47

Chapter 3 Classification Tests

Standard Test Procedures

MAY 2001

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Chapter 3 Classification Tests

Standard Test Procedures

MAY 2001

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

CHAPTER 4 DRY DENSITY – MOISTURE CONTENT RELATIONSHIP

4.1

General Requirements

4.1.1

Introduction. Compaction is defined as the process of increasing soil unit weight by forcing soil solids into a tighter state and reducing the air voids and thus increasing the stability and supporting capacity of soil. This is accomplished by applying static or dynamic loads to the soil. Laboratory compaction tests provide the basis for control procedures used on earthworks, sub-grades and also for pavement works on site.

4.1.2

Scope. Based upon the site conditions, nature of the works, the type of soil and the type of compaction equipment used, two types of tests are applied (1) Using rammer methods of compaction and (2) using vibrating methods of compaction.

4.1.3

Definitions and terminology. Definitions for the terminology used in compaction tests are given in Chapter 1. The terminology used in compaction tests is illustrated in Figure 4.1.1.

0% 5%

Air void lines for a given particle density

% 10

Dry density Mg/m

3

Maximum dry density

Compaction curve

0

Optimum moisture content

Saturation line

Moisture Content

Figure 4.1.1 Terminology used in compaction tests 4.1.4

Choice of compaction procedure A 1L internal volume compaction mould is used when not more than 5% of the soil particles are retained on a 20 mm sieve. Both the 2.5 kg and 4.5 kg rammer methods may be used. If there is a limited amount of particles up to 37.5 mm equivalent tests are carried out in the larger California Bearing Ratio (CBR) mould. The second type of test makes use of a vibrating hammer and is intended mainly for granular soils passing 37.5 mm test sieve, with not more than 30% retained on a 20 mm test sieve. The soil is compacted into a CBR mould. MAY 2001

Page 4.1

Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

4.2

Sample Preparation

4.2.1

General. For soils containing particles not susceptible to crushing, one sample is required for test and it can be used several times after progressively increasing the amount of water. For soils containing particles which are susceptible to crushing it is necessary to prepare separate batches of soil at different moisture contents. Consequently, a much larger sample is required. It may be necessary to carry out a trial compaction to determine whether the soil is susceptible to crushing. For stiff, cohesive soils, suggested methods are to shred the soil so that it could pass through a 5 mm test sieve, or to chop it into pieces, e.g. to pass a 20 mm sieve.

4.2.2

Preliminary assessment of soil. An assessment of the soil is required in order to determine which method of compaction should be used and the sample size required. The first assessment is to decide if the soil is susceptible to crushing, i.e. whether it contains weak particles which will crush during compaction with a 2.5 kg rammer. If sufficient sample is available it is preferable to use a method which assumes that the soil susceptible to crushing. The second assessment is to decide the approximate percentages (to an accuracy of ±5%) by mass of particles passing the 20 mm and 37.5 mm sieves. Having determined the approximate percentages passing the 37.5 mm and 20 mm sieves, the compaction test sample can be assigned to one of six grading zones. These are numbered 1 to 5 and (x) and defined in Table 4.2.1.

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

Table 4.2.1 Summary of sample preparation methods Grading zone

Minimum percentage passing test sieves

Preparation procedure Table reference

Minimum mass of prepared soil required

20 mm

37.5

(a)

(a)

(1)

100%

100%

(2)

95

100

(3)

70

100

(4)

70

95

(5) (X)

70 Less

90 Less

) ) ) ) ) ) ) ) ) )

(b)

) ) 4.2

4.4

Type of

(b)

kg 6

kg 15

1L

4.3

) ) 4.5 ) 16 40 ) ) (Tests not applicable)

CBR

(a) Soil particles not susceptible to crushing during compaction. (b) Soil particles susceptible to crushing during compaction. 1L = one-litre compaction mould. CBR = CBR mould. Table 4.2.1 also gives the method of sample preparation, the minimum mass of soil required and the type of mould to be used for the compaction test. 4.2.3

Preparation procedure. The procedure to be adopted depends on the grading zone into which the sample falls (see Table 4.2.1) and whether the soil is susceptible to crushing. The procedures are given hereafter in a series of tables, detailed as follows; a) Table 4.2.2. Using 1L compaction mould for soils not susceptible to crushing. Grading Zones : 1 and 2. b) Table 4.2.3. Using 1L compaction mould for soils susceptible to crushing. Grading Zones : 1 and 2. c) Table 4.2.4. Using CBR compaction mould for soils not susceptible to crushing. Grading Zones : 3, 4 and 5. d) Table 4.2.5. Using CBR compaction mould for soils susceptible to crushing. Grading Zones : 3, 4 and 5. MAY 2001

Page 4.3

Chapter 4 Dry Density – Moisture Content Relationship

Table 4.2.2

Sample preparation procedure

Standard Test Procedures

Using 1L mould

1 2 Min. % passing 37.5 mm = 100% Min. % passing 37.5 mm = 100% Min. % passing 20mm = 100% Min. % passing 20mm = 95% If soil is too wet to process, air or oven dry at not more than 500 C. Avoid drying completely. Gently break aggregation of soil. Determine moisture content. Weigh to 0.1% by mass the whole sample and record the mass. Riffle/quarter to about 6 kg Remove and weigh to 0.1% by passing 20 mm. mass the material retained on 20 mm sieve. Discard the material. Calculate additional water required Determine moisture content. for 1st compaction point, e.g. sandy and gravelly soils start at Riffle/quarter to about 6 kg 4%-6%, for cohesive soils start at passing 20 mm. 8%-10% below plastic limit. Add required water and mix thoroughly. Store mixed material in sealed container for minimum 24 h before compaction (particularly for cohesive soils). Note : Care should be taken in drying samples which may suffer irreversible changes as a result.

Soils not susceptible to crushing Grading zone 3 4 Min. % passing 37.5 mm = 100% Min. % passing 37.5 mm = 95% Min. % passing 20mm = 70% Min. % passing 20mm = 70%

5 Min. % passing 37.5 mm = 90% Min. % passing 20mm = 70%

1L mould not suitable for this soil grading

1L mould not suitable for this soil grading

1L mould not suitable for this soil grading

Calculate additional water required for 1st compaction point, e.g. sandy and gravelly soils start at 4%-6%, for cohesive soils start at 8%-10% below plastic limit. Add required water and mix thoroughly Store mixed material in sealed container for minimum 24 h before compaction (particularly for cohesive soils) Note : Care should be taken in drying samples which may suffer irreversible changes as a result. Note : As an alternative, the whole sample could be compacted in a CBR mould. In this case, material retained on 20 mm is not discarded.

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Chapter 4 Dry Density – Moisture Content Relationship

Table 4.2.3

Sample preparation procedure

Standard Test Procedures

Using 1L mould

1 2 Min. % passing 37.5 mm = 100% Min. % passing 37.5 mm = 100% Min. % passing 20mm = 100% Min. % passing 20mm = 95% If soil is too wet to process, air or oven dry at not more than 500 C. Avoid drying completely. Gently break aggregations of soil. Determine moisture content. Weigh to 0.1% by mass the whole sample and record the mass. Riffle/quarter sample into 5 or Remove and weigh to 0.1% by more representative samples, mass the material retained on 20 each of about 2.5 kg. mm sieve. Discard the material. Add required water and mix Determine moisture content. thoroughly (see individual test methods). Increments of 1%-2% Riffle/quarter sample into 5 or are appropriate for sandy and more representative samples, gravelly soils, and of 2%-4% for each of about 2.5 kg. cohesive soils. Store mixed material in sealed Add required water and mix container for minimum 24 h before thoroughly (see individual test compaction (particularly for methods). Increments of 1%-2% cohesive soils). are appropriate for sandy and gravelly soils, and of 2%-4% for Note : Care should be taken in cohesive soils. drying samples which may suffer irreversible changes as a result. Store mixed material in sealed container for minimum 24 h before compaction (particularly for cohesive soils) Note : Care should be taken in drying samples which may suffer irreversible changes as a result. Note : As an alternative, the whole sample could be compacted in a CBR mould. In this case, material retained on 20 mm is not discarded.

MAY 2001

Soils not susceptible to crushing Grading zone 3 4 Min. % passing 37.5 mm = 100% Min. % passing 37.5 mm = 95% Min. % passing 20mm = 70% Min. % passing 20mm = 70%

5 Min. % passing 37.5 mm = 90% Min. % passing 20mm = 70%

1L mould not suitable for this soil grading

1L mould not suitable for this soil grading

1L mould not suitable for this soil grading

Page 4.5

Chapter 4 Dry Density – Moisture Content Relationship

Table 4.2.4

Sample preparation procedure

Standard Test Procedures

Using CBR mould

1 Min. % passing 37.5 mm = 100% Min. % passing 20mm = 100%

2 Min. % passing 37.5 mm = 100% Min. % passing 20mm = 95%

Soils of this grading are more usually compacted in 1L moulds, except when CBR tests are to be carried out.

Soils of this grading are more usually compacted in 1L moulds, except when CBR tests are to be carried out.

Soils not susceptible to crushing Grading zone 3 4 5 Min. % passing 37.5 mm = 100% Min. % passing 37.5 mm = 95% Min. % passing 37.5 mm = 90% Min. % passing 20mm = 70% Min. % passing 20mm = 70% Min. % passing 20mm = 70% If soil is too wet to process, air or oven dry at not more than 500 C. Avoid drying completely. Gently break aggregation of soil. Determine moisture content Weigh to 0.1% by mass the whole sample and record the mass. Riffle/quarter to about 15 kg. Remove and weigh the material Remove and weigh the material retained on 37.5 mm. Discard this retained on 37.5 mm. Discard this material. material. Calculate additional water required for 1st compaction point, e.g. sandy and gravelly soils start at 4%-6%, for cohesive soils start at 8%-10% below plastic limit.

Determine moisture content.

Add required water and mix thoroughly.

Calculate additional water required for 1st compaction point, e.g. sandy and gravelly soils start at 4%-6%, for cohesive soils start at 8%-10% below plastic limit.

Determine moisture content.

Add required water and mix thoroughly.

Calculate additional water required for 1st compaction point, e.g. sandy and gravelly soils start at 4%-6%, for cohesive soils start at 8%-10% below plastic limit.

Store mixed material in sealed container for minimum 24 h before compaction (particularly for cohesive soils)

Note : Care should be taken in drying samples which may suffer irreversible changes as a result.

Riffle/quarter to about 25 kg.

Store mixed material in sealed container for minimum 24 h before compaction (particularly for cohesive soils) Note : Care should be taken in drying samples which may suffer irreversible changes as a result.

Replace this material by the same quantity of material of similar characteristics which passes 37.5 mm and is retained on 20 mm.

Riffle/quarter to about 15 kg.

Add required water and mix thoroughly. Store mixed material in sealed container for minimum 24 h before compaction (particularly for cohesive soils) Note : Care should be taken in drying samples which may suffer irreversible changes as a result.

MAY 2001

Page 4.6

Chapter 4 Dry Density – Moisture Content Relationship

Table 4.2.5

Sample preparation procedure

Standard Test Procedures

Using CBR mould

1 Min. % passing 37.5 mm = 100% Min. % passing 20mm = 100%

2 Min. % passing 37.5 mm = 100% Min. % passing 20mm = 95%

Soils of this grading are more usually compacted in 1L moulds, except when CBR tests are to be carried out.

Soils of this grading are more usually compacted in 1L moulds, except when CBR tests are to be carried out.

MAY 2001

Soils not susceptible to crushing Grading zone 3 4 5 Min. % passing 37.5 mm = 100% Min. % passing 37.5 mm = 95% Min. % passing 37.5 mm = 90% Min. % passing 20mm = 70% Min. % passing 20mm = 70% Min. % passing 20mm = 70% If soil is too wet to process, air or oven dry at not more than 500 C. Avoid drying completely. Gently break aggregation of soil. Determine moisture content Weigh to 0.1% by mass the whole sample and record the mass. Riffle/quarter sample into 5 or Remove and weigh the material Replace this material by the same more representative samples each retained on 37.5 mm. Discard this quantity of material of of about 6 kg. material. similar characteristics which passes 37.5 mm and is retained on 20 mm. Add required water and mix Determine moisture content. Determine moisture content. thoroughly (see individual test methods). Increments of 1%-2% Riffle/quarter sample into 5 or Riffle/quarter sample into 5 or are appropriate for sandy and more representative samples each more representative gravelly soils, and of 2%-4% for of about 6 kg. samples each of about cohesive soils. 6 kg. Store mixed material in sealed Add required water and mix Add required water and mix container for minimum 24 h before thoroughly (see individual test thoroughly (see compaction (particularly for methods). Increments of 1%-2% individual test cohesive soils) are appropriate for sandy and methods). Increments gravelly soils, and of 2%-4% for of 1%-2% are cohesive soils. appropriate for sandy and gravelly soils, and of 2%-4% for cohesive soils. Note : Care should be taken in Store mixed material in sealed Store mixed material in sealed drying samples which may suffer container for minimum 24 h before container for minimum irreversible changes as a result. compaction (particularly for 24 h before cohesive soils) compaction (particularly for cohesive soils) Note : Care should be taken in Note : Care should be taken in drying samples which may suffer drying samples which irreversible changes as a result. may suffer irreversible changes as a result.

Page 4.7

Chapter 4 Dry Density – Moisture Content Relationship 4.2.4

Standard Test Procedures

Modifying soil moisture content. When carrying out compaction tests it may be necessary to change the moisture content of the soil, either to a lower value, or to a higher value. The required calculations are: a) To decrease the moisture content from a value of x% to a value of y%, the mass of water required to be lost is;

x-y x M grams 100 + x where, M is the mass of the wet soil b) To increase the moisture content from a value of x% to a value of z%, the mass of water to be added is;

z- x x M grams 100 + x 4.3

Standard Compaction using 2.5 kg Rammer

4.3.1

Scope. This test method determines the optimum moisture content and maximum dry density of a soil when compacted into a mould in three layers using a 2.5 kg rammer falling through a height of 300 mm. In this method, 1L mould is used for soils passing 20 mm sieve and CBR mould is used for soils containing not more than 30% by mass of material on the 20 mm sieve which may include some particles retained on the 37.5 mm sieve.

4.3.2

Apparatus. The following general apparatus is required for the test : a) b) c) d)

2.5 kg compaction rammer (see Figure 4.3.1). Sieves of 20 mm and 37.5 mm, with receiver. Spatula or palette knife. Straight edge, e.g. a steel strip about 300 mm long, 25 mm wide, and 3 mm thick, with one beveled edge. e) Sample tray of plastics or corrosion-resistant metal with sides, e.g. about 80 mm deep. f) Apparatus for the determination of moisture content. g) Scoop. h) Additionally for test using 1L mould : a compaction mould similar to the one shown in Figure 4.3.2; a balance readable to 1 g. i) Additionally for test using CBR mould : a compaction mould similar to the one shown in Figure 4.3.3; a balance readable to 5 g.

MAY 2001

Page 4.8

Chapter 4 Dry Density – Moisture Content Relationship 4.2.4

Standard Test Procedures

Modifying soil moisture content. When carrying out compaction tests it may be necessary to change the moisture content of the soil, either to a lower value, or to a higher value. The required calculations are: a) To decrease the moisture content from a value of x% to a value of y%, the mass of water required to be lost is;

x-y x M grams 100 + x where, M is the mass of the wet soil b) To increase the moisture content from a value of x% to a value of z%, the mass of water to be added is;

z- x x M grams 100 + x 4.3

Standard Compaction using 2.5 kg Rammer

4.3.1

Scope. This test method determines the optimum moisture content and maximum dry density of a soil when compacted into a mould in three layers using a 2.5 kg rammer falling through a height of 300 mm. In this method, 1L mould is used for soils passing 20 mm sieve and CBR mould is used for soils containing not more than 30% by mass of material on the 20 mm sieve which may include some particles retained on the 37.5 mm sieve.

4.3.2

Apparatus. The following general apparatus is required for the test : a) b) c) d)

2.5 kg compaction rammer (see Figure 4.3.1). Sieves of 20 mm and 37.5 mm, with receiver. Spatula or palette knife. Straight edge, e.g. a steel strip about 300 mm long, 25 mm wide, and 3 mm thick, with one beveled edge. e) Sample tray of plastics or corrosion-resistant metal with sides, e.g. about 80 mm deep. f) Apparatus for the determination of moisture content. g) Scoop. h) Additionally for test using 1L mould : a compaction mould similar to the one shown in Figure 4.3.2; a balance readable to 1 g. i) Additionally for test using CBR mould : a compaction mould similar to the one shown in Figure 4.3.3; a balance readable to 5 g.

MAY 2001

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

4 holes 6 mm dia RAMMER mass = 2.5 kg±25 g

GUIDE length of travel of rammer = 300 mm 330 mm 350 mm

25 mm dia

12 holes 6 mm dia 2 mm rubber gasket 48 mm 52 mm dia

50 mm dia

50 mm dia

Figure 4.3.1 BS 2.5 kg compaction rammer 118 mm dia extension collar

50 mm

three lugs

10 mm push fit mould body

105 mm dia

three pins

115.5 mm 10 mm 13 mm

baseplate 180 mm dia or 150 mm square

Figure 4.3.2 BS 1 L compaction mould

MAY 2001

Page 4.9

MAY 2001 10 mm

13 mm

Two lugs

three pins

three lugs

screw thread

230 mm dia or 200 mm square

127 mm

152 mm dia

10 mm

50 mm

165 mm dia

10 mm

127 mm

152 mm dia

168 mm dia 162 mm dia

50 mm

152 mm dia

Figure 4.3.3 Types of BS CBR compaction moulds

baseplate

mould body

push fit

extension collar

detachable base plate

mould body

extension collar

580 mm

128 mm

510 mm

50 mm dia

Figure 4.4.1 BS 4.5 kg compaction rammer

60 mm dia

52 mm dia

12 holes 6 mm dia

GUIDE length of travel of rammer = 450 mm

4 holes 6 mm dia

2 mm rubber gasket

25 mm dia

RAMMER total mass 4.5 kg±50 kg

Chapter 4 Dry Density – Moisture Content Relationship Standard Test Procedures

Page 4.10

Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

4.3.3

Calibration of apparatus

4.3.3.1

Types of moulds. The standard sizes for compaction moulds are detailed in Table 4.3.1. Table 4.3.1. Standard sizes for compaction moulds Type of mould

Nominal dimensions Diamet Height Volume mm mm cm3 105 115.5 1000

‘One litre’ CBR

152

127

2305

Height of extension, mm 50 minimum 50 minimum

4.3.3.2. Mould factors. The volume of the mould can be determined using vernier calipers. Measure its internal diameter (D mm) and length (L mm) in places to 0.1 mm. Calculate the mean dimensions, and the volume of the mould (V cm3) from the equation.

V =

π x D2 x L 4

If necessary, mould factors can be determined. The use of these factors may make calculations easier. Since the factors depend on physical measurements it is necessary to recalculate the values whenever changes in the measurements are suspected. 4.3.3.2.1 Mould area factors. The mould area factor, F is the reciprocal of the cross-sectional area in square meters, i.e.

F =

4 (1000)2 sq.m -1 2 π (D )

where, D = mould diameter in millimeters Example For the 1L compaction mould the mould area factor is :

F =

4 (1000)2 = 1273 . x 90.703 = 115.49 sq.m-1 π (105)2

4.3.3.2.2 Mould height factors. The mould height factor. H, is the same as the height of the mould in millimetres. For the 1L mould, the mould height factor is 115.5. 4.3.3.2.3 Mould factor ratio The mould factor ratio is calculated as

F H

For the 1L mould this is calculated as 1.000 4.3.4

Preparation of sample. The sample should be prepared in accordance with the requirements of Tables 4.2.2 or 4.2.3 for soils with particles up to medium gravel size 4.2.4 or 4.2.5 for soils with some coarse gravel size particles depending on whether the MAY 2001

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

soil is susceptible to crushing. When using Table 4.2.3 or 4.2.5, it can be useful to have more than 5 prepared sub-samples, in case further points need to be established on the compaction curve. 4.3.5

Test procedure

4.3.5.1

The mould including the base-plate is first weighed to an accuracy of 1 gm for medium gravel and 5 gms for coarse gravel (m1). Measure the internal dimensions to 0.1 mm for medium gravel and 0.5 mm for coarse gravel size.

4.3.5.2

Attach the extension (collar) to the mould and place the mould assembly on a solid base, e.g. a concrete floor.

4.3.5.3

The prepared sample of moist material is divided into three approximately equal portions.

4.3.5.4

Sufficient material from the first portion is then placed in the mould so that the mould is about a third full when the soil has been compacted. This first layer is then compacted using 27 blows for 1L mould and 62 blows for CBR mould of the 2.5 kg rammer dropping from a controlled height of 300 mm. The blows should be evenly distributed over the surface of the material and care should be taken to ensure that soil does not stick to the face of the hammer, thus reducing the height of fall.

4.3.5.5

Material from the second and third portions is then placed in the mould, each portion being compacted as above. The purpose of this procedure is to compact the soil in three equal layers and on completion, the mould should be completely filled. On removal of the collar, the top surface of the soil should be proud of the top rim of the mould body by an amount not exceeding 6 mm. If the soil is below the top rim of the mould or is proud of the mould by more than 6 mm, the test must be repeated.

4.3.5.7

The soil above the mould rim should then be struck off level with a metal straight edge. With some coarse-grained materials it may be difficult to obtain a smooth surface. Replace any coarse particles, removed in the leveling process, by finer material from the sample, well pressed in.

4.3.5.7

The mould, base-plate and soil are then weighed, to an accuracy of 1 gram for 1L mould and 5 gram for CBR mould (m2).

4.3.5.8

Remove the compacted soil from the mould and place it on the metal tray. Take a representative sample for determination of moisture content.

4.3.5.9

For soils not susceptible to crushing break up the remainder of the soil, rub it through the 20 mm sieve and mix with the remainder of the prepared test sample. In case of soils susceptible to crushing, discard the remaining soil from each of the 5 approximately 2.5 kg representative sub-samples.

4.3.5.10 Increase moisture 1% to 2% for sandy or gravelly soils and 2% to 4% for cohesive soils and mix thoroughly into the soil. As the test progresses, the size of the increments can be decreased to increase accuracy in determining the optimum moisture content. 4.3.5.11 Repeat steps 4.3.5.3 to 4.3.5.10 to give a total of at least 5 determinations. The moisture contents shall include the optimum moisture content, at which the maximum dry density occurs, this point being as near to the middle of the range as is practicable to achieve. Note.

Tables 4.2.2 to 4.2.5 recommend that samples of prepared soil be allowed to “cure” for 24 h before test, particularly if they are cohesive. Good laboratory MAY 2001

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Standard Test Procedures

soil is susceptible to crushing. When using Table 4.2.3 or 4.2.5, it can be useful to have more than 5 prepared sub-samples, in case further points need to be established on the compaction curve. 4.3.5

Test procedure

4.3.5.1

The mould including the base-plate is first weighed to an accuracy of 1 gm for medium gravel and 5 gms for coarse gravel (m1). Measure the internal dimensions to 0.1 mm for medium gravel and 0.5 mm for coarse gravel size.

4.3.5.2

Attach the extension (collar) to the mould and place the mould assembly on a solid base, e.g. a concrete floor.

4.3.5.3

The prepared sample of moist material is divided into three approximately equal portions.

4.3.5.4

Sufficient material from the first portion is then placed in the mould so that the mould is about a third full when the soil has been compacted. This first layer is then compacted using 27 blows for 1L mould and 62 blows for CBR mould of the 2.5 kg rammer dropping from a controlled height of 300 mm. The blows should be evenly distributed over the surface of the material and care should be taken to ensure that soil does not stick to the face of the hammer, thus reducing the height of fall.

4.3.5.5

Material from the second and third portions is then placed in the mould, each portion being compacted as above. The purpose of this procedure is to compact the soil in three equal layers and on completion, the mould should be completely filled. On removal of the collar, the top surface of the soil should be proud of the top rim of the mould body by an amount not exceeding 6 mm. If the soil is below the top rim of the mould or is proud of the mould by more than 6 mm, the test must be repeated.

4.3.5.7

The soil above the mould rim should then be struck off level with a metal straight edge. With some coarse-grained materials it may be difficult to obtain a smooth surface. Replace any coarse particles, removed in the leveling process, by finer material from the sample, well pressed in.

4.3.5.7

The mould, base-plate and soil are then weighed, to an accuracy of 1 gram for 1L mould and 5 gram for CBR mould (m2).

4.3.5.8

Remove the compacted soil from the mould and place it on the metal tray. Take a representative sample for determination of moisture content.

4.3.5.9

For soils not susceptible to crushing break up the remainder of the soil, rub it through the 20 mm sieve and mix with the remainder of the prepared test sample. In case of soils susceptible to crushing, discard the remaining soil from each of the 5 approximately 2.5 kg representative sub-samples.

4.3.5.10 Increase moisture 1% to 2% for sandy or gravelly soils and 2% to 4% for cohesive soils and mix thoroughly into the soil. As the test progresses, the size of the increments can be decreased to increase accuracy in determining the optimum moisture content. 4.3.5.11 Repeat steps 4.3.5.3 to 4.3.5.10 to give a total of at least 5 determinations. The moisture contents shall include the optimum moisture content, at which the maximum dry density occurs, this point being as near to the middle of the range as is practicable to achieve. Note.

Tables 4.2.2 to 4.2.5 recommend that samples of prepared soil be allowed to “cure” for 24 h before test, particularly if they are cohesive. Good laboratory MAY 2001

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practice should allow this is most cases. However, and in particular when testing sandy or gravelly soils, it may be possible to reduce or omit this requirement altogether. In the latter case, an estimate can be made of the likely optimum moisture content, and the first sub-sample made up and compacted immediately at that moisture content, following the procedures in 4.3.5.1 to 4.3.5.8.. The necessary weighings and calculations should be recorded on the test sheet. The compaction procedure is then repeated on two further sub-samples, at appropriate moisture contents above and below the estimated optimum. At this stage an estimate can be made of the dry densities of the specimens, using the calculated bulk densities and the assumption that the moisture contents are in fact what they were made up to be. From this information it can be determined where the three points are likely to lie on the final moisture content / dry density relationship curve, and the remaining specimens can then be moistened and compacted accordingly. This method can achieve reliable results on suitable soils if carefully carried out. 4.3.6

Calculation and expression of results

4.3.6.1

Calculate the internal volume of the mould. V (in cm3).

4.3.6.2 Calculate the bulk density, ρ (in Mg/m3) of each of the compacted specimens from the equation

ρ =

m2 − m1 V

where, m1 is the mass of mould and base-plate (in g); m2 is the mass of mould, base-plate and compacted soil (in g). Note.

Where the height of the compacted soil specimen is the same as the height of the compaction mould body, e.g. in the case of the 2.5 kg and 4.5 kg rammer methods, the mould factors can be used to calculate the bulk density of the soil as;

 F ρ = m 2 − m1 x    H In the vibrating hammer test, where the height of the compacted soil specimen may be different from the height of the compaction mould body the calculation then becomes

ρ =

m2 − m1 x F H - h

Refer to Part 4.5 and Forms 4.3.1 to 4.3.4. The dry density ρd of each compacted specimen is then calculated (in kg/m3) using the formula; Dry density,

ρd = ρ x

100 100 + w

Where, w is the moisture content of the soil.

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Chapter 4 Dry Density – Moisture Content Relationship

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practice should allow this is most cases. However, and in particular when testing sandy or gravelly soils, it may be possible to reduce or omit this requirement altogether. In the latter case, an estimate can be made of the likely optimum moisture content, and the first sub-sample made up and compacted immediately at that moisture content, following the procedures in 4.3.5.1 to 4.3.5.8.. The necessary weighings and calculations should be recorded on the test sheet. The compaction procedure is then repeated on two further sub-samples, at appropriate moisture contents above and below the estimated optimum. At this stage an estimate can be made of the dry densities of the specimens, using the calculated bulk densities and the assumption that the moisture contents are in fact what they were made up to be. From this information it can be determined where the three points are likely to lie on the final moisture content / dry density relationship curve, and the remaining specimens can then be moistened and compacted accordingly. This method can achieve reliable results on suitable soils if carefully carried out. 4.3.6

Calculation and expression of results

4.3.6.1

Calculate the internal volume of the mould. V (in cm3).

4.3.6.2 Calculate the bulk density, ρ (in Mg/m3) of each of the compacted specimens from the equation

ρ =

m2 − m1 V

where, m1 is the mass of mould and base-plate (in g); m2 is the mass of mould, base-plate and compacted soil (in g). Note.

Where the height of the compacted soil specimen is the same as the height of the compaction mould body, e.g. in the case of the 2.5 kg and 4.5 kg rammer methods, the mould factors can be used to calculate the bulk density of the soil as;

 F ρ = m 2 − m1 x    H In the vibrating hammer test, where the height of the compacted soil specimen may be different from the height of the compaction mould body the calculation then becomes

ρ =

m2 − m1 x F H - h

Refer to Part 4.5 and Forms 4.3.1 to 4.3.4. The dry density ρd of each compacted specimen is then calculated (in kg/m3) using the formula; Dry density,

ρd = ρ x

100 100 + w

Where, w is the moisture content of the soil.

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

The determined moisture content should be within 1% of the required moisture content if the mixing and testing has been carried out correctly. The graph of dry density vs moisture content is then plotted as in Figure 4.1.1. The points should be joined by a curve of best fit. The maximum dry density (MDD) and corresponding optimum moisture content (OMC) are then determined from the graph. Read off these values to three significant figures. Note.

4.3.6.3

The maximum on the curve may lie between two points, but when drawing the curve, care should be taken not to exaggerate its peak.

If required, curves corresponding to air void contents can be plotted on the same graph (see Figure 4.1.1). These are calculated from the equation

Va 100 ρd = 1 w ρs 100 ρ w 1 -

where,

ρd ρs ρw Va w

4.3.7

is the dry density (in kg/m3); is the particle density (in kg/m3); is the density of water (in kg/m3), assumed equal to 1; is the volume of air voids in the soil expressed as a percentage of the total volume of the soil (equal to 0%, 5%, 10% for the purpose of the example); is the moisture content (in %).

Report. The test report shall contain the following information : a) the method of test used; b) the sample preparation procedure, and whether a single sample or separate samples were used. In the case of stiff, cohesive soil the size of pieces to which the soil was broken down shall be stated; c) the experimental points and the smooth curve drawn through them showing the relationship between moisture content and dry density; d) the dry density corresponding to the maximum dry density on the moisture content / dry density curve, reported as the maximum dry density to the nearest 0.01 (in Mg/m3); e) the percentage moisture content corresponding to the maximum dry density on the moisture content / dry density curve, reported as the optimum moisture content to two significant figures; f) the amount of stone retained on the 20 mm and 37.5 mm test sieves reported to the nearest 1% by dry mass; g) the particle density and whether measured (and if so the method used) or assumed. Examples of completed test sheets are given in Forms 4.3.1 to 4.3.4. In addition to the information above, the test sheets should contain full details of the sample description and location etc. The operator should sign and date the test sheets.

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

The determined moisture content should be within 1% of the required moisture content if the mixing and testing has been carried out correctly. The graph of dry density vs moisture content is then plotted as in Figure 4.1.1. The points should be joined by a curve of best fit. The maximum dry density (MDD) and corresponding optimum moisture content (OMC) are then determined from the graph. Read off these values to three significant figures. Note.

4.3.6.3

The maximum on the curve may lie between two points, but when drawing the curve, care should be taken not to exaggerate its peak.

If required, curves corresponding to air void contents can be plotted on the same graph (see Figure 4.1.1). These are calculated from the equation

Va 100 ρd = 1 w ρs 100 ρ w 1 -

where,

ρd ρs ρw Va w

4.3.7

is the dry density (in kg/m3); is the particle density (in kg/m3); is the density of water (in kg/m3), assumed equal to 1; is the volume of air voids in the soil expressed as a percentage of the total volume of the soil (equal to 0%, 5%, 10% for the purpose of the example); is the moisture content (in %).

Report. The test report shall contain the following information : a) the method of test used; b) the sample preparation procedure, and whether a single sample or separate samples were used. In the case of stiff, cohesive soil the size of pieces to which the soil was broken down shall be stated; c) the experimental points and the smooth curve drawn through them showing the relationship between moisture content and dry density; d) the dry density corresponding to the maximum dry density on the moisture content / dry density curve, reported as the maximum dry density to the nearest 0.01 (in Mg/m3); e) the percentage moisture content corresponding to the maximum dry density on the moisture content / dry density curve, reported as the optimum moisture content to two significant figures; f) the amount of stone retained on the 20 mm and 37.5 mm test sieves reported to the nearest 1% by dry mass; g) the particle density and whether measured (and if so the method used) or assumed. Examples of completed test sheets are given in Forms 4.3.1 to 4.3.4. In addition to the information above, the test sheets should contain full details of the sample description and location etc. The operator should sign and date the test sheets.

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Chapter 4 Dry Density – Moisture Content Relationship

MAY 2001

Standard Test Procedures

Page 4.15

Chapter 4 Dry Density – Moisture Content Relationship

MAY 2001

Standard Test Procedures Form 4.3.2

Page 4.16

Chapter 4 Dry Density – Moisture Content Relationship

MAY 2001

Standard Test Procedures

Page 4.17

Chapter 4 Dry Density – Moisture Content Relationship

MAY 2001

Standard Test Procedures

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

4.4

Heavy Compaction using 4.5 kg Rammer

4.4.1

Scope. This type of compaction is widely used for pavement materials and also for earthworks and sub-grades if a high standard of compaction is specified. This method may be carried out in the 1L compaction mould or in a CBR mould.

4.4.2

Apparatus, sample preparation and test procedure. The test is similar to the standard compaction (2.5 kg rammer) as described earlier, the only differences being that the sample is compacted in 5 equal layers with the 4.5 kg rammer dropping from a controlled height of 450 mm. The 4.5 kg rammer is shown in Figure 4.4.1. As previously each layer still receives 27 blows / layer for a 1L mould and 62 blows / layer for a CBR mould. Calculation and reporting of results are identical to those for 2.5 kg rammer compaction test.

4.5

Vibrating Hammer Method

4.5.1

Scope. This test is applicable to granular soils containing no more than 30% by mass of material retained on the 20 mm sieve, which may include some particles retained on the 37.5 mm sieve. It is not generally suitable for cohesive soils. The principle is similar to that of the rammer procedures except that a vibrating hammer is used instead of a drop-weight rammer, and a larger mould (the standard CBR mould) is necessary.

4.5.2

Apparatus a) Cylindrical metal mould, internal dimensions 152 mm diameter and 127 mm high (CBR mould). The mould can be fitted with an extension collar and base-plate. The mould is shown in Figure 4.3.3. b) Electric vibrating hammer, power consumption 600-800 W, operating at a frequency in the range 25-60 Hz. For safety reasons the hammer should operate on 110V and an earth-leakage circuit breaker (ELCB) should be included in the line between the hammer and the mains supply. c) Steel tamper for attaching to the vibrating hammer with a circular foot 145 mm diameter (see Figure 4.5.1 a) and b)). d) A balance readable to 5 g. e) 20 mm and 37.5 mm BS sieves and receiver. f) A straightedge, e.g. a steel strip about 300 mm long, 25 mm wide and 3 mm thick, with one beveled edge. g) Depth gauge or steel rule reading to 0.5 mm. h) Apparatus for the determination of moisture content. i) Laboratory stop-clock reading to 1 s. j) A corrosion-resistant metal or plastic trays with sides, e.g. about 80 mm deep of a size suitable for the quantity of material to be used. k) A scoop. l) Apparatus for extracting compacted specimens from the mould (optional).

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

4.4

Heavy Compaction using 4.5 kg Rammer

4.4.1

Scope. This type of compaction is widely used for pavement materials and also for earthworks and sub-grades if a high standard of compaction is specified. This method may be carried out in the 1L compaction mould or in a CBR mould.

4.4.2

Apparatus, sample preparation and test procedure. The test is similar to the standard compaction (2.5 kg rammer) as described earlier, the only differences being that the sample is compacted in 5 equal layers with the 4.5 kg rammer dropping from a controlled height of 450 mm. The 4.5 kg rammer is shown in Figure 4.4.1. As previously each layer still receives 27 blows / layer for a 1L mould and 62 blows / layer for a CBR mould. Calculation and reporting of results are identical to those for 2.5 kg rammer compaction test.

4.5

Vibrating Hammer Method

4.5.1

Scope. This test is applicable to granular soils containing no more than 30% by mass of material retained on the 20 mm sieve, which may include some particles retained on the 37.5 mm sieve. It is not generally suitable for cohesive soils. The principle is similar to that of the rammer procedures except that a vibrating hammer is used instead of a drop-weight rammer, and a larger mould (the standard CBR mould) is necessary.

4.5.2

Apparatus a) Cylindrical metal mould, internal dimensions 152 mm diameter and 127 mm high (CBR mould). The mould can be fitted with an extension collar and base-plate. The mould is shown in Figure 4.3.3. b) Electric vibrating hammer, power consumption 600-800 W, operating at a frequency in the range 25-60 Hz. For safety reasons the hammer should operate on 110V and an earth-leakage circuit breaker (ELCB) should be included in the line between the hammer and the mains supply. c) Steel tamper for attaching to the vibrating hammer with a circular foot 145 mm diameter (see Figure 4.5.1 a) and b)). d) A balance readable to 5 g. e) 20 mm and 37.5 mm BS sieves and receiver. f) A straightedge, e.g. a steel strip about 300 mm long, 25 mm wide and 3 mm thick, with one beveled edge. g) Depth gauge or steel rule reading to 0.5 mm. h) Apparatus for the determination of moisture content. i) Laboratory stop-clock reading to 1 s. j) A corrosion-resistant metal or plastic trays with sides, e.g. about 80 mm deep of a size suitable for the quantity of material to be used. k) A scoop. l) Apparatus for extracting compacted specimens from the mould (optional).

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

Vibrating Hammer Assembly Figure 4.5.1 (a)

Tamper for Vibrating Hammer Compaction Test Figure 4.5.1 (b)

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

4.5.3

Calibration of apparatus

4.5.3.1

General. The vibrating hammer shall be maintained in accordance with the manufacturer’s instructions. Its working parts shall not be badly worn. The calibration test described in 4.5.3.3 below shall be carried out to determine whether the vibrating hammer is in satisfactory working order, and able to comply with the requirements of the test.

4.5.3.2

Material. Clean, dry silica sand, from the (geological) Woburn Beds of the Lower Greensand in the Leighton Buzzard district of the UK. The grading shall be such that at least 75% passes the 600 µm sieve and is retained on the 425 µm sieve. Dry and not previously used sand shall be used. This sand shall be sieved through 1 600 µm test sieve and the coarse fraction shall be discarded. Note.

4.5.3.3

This is the standard sand as described in the British Standard. Advice on suitable suppliers can be obtained from BSI in the UK. Advice should be sought from BRRL as to whether a suitable sand is available locally, to reduce dependence on costly imports.

Calibration test a) Take a 5±0.1 kg sample of the specified in 4.5.3.2, which has not been used previously and mix it with water in order to raise its moisture content to 2.5±0.5%. b) Compact the wet sand in a cylindrical metal mould of 152 mm diameter and 127 mm depth, using the vibrating hammer as specified in the section on apparatus above. c) Carry out a total of three tests, all on the same sample of sand, and determine the mean dry density. Determine the dry density values to the nearest 0.002 Mg/m3. Note.

The operator can usually judge the required pressure to apply with sufficient accuracy after carrying out the check described in 4.5.4 below.

d) If the range of values in the three tests exceeds 0.01 Mg/ m3, repeat the procedure. Consider the vibrating hammer suitable for use in the vibrating compaction test if the mean dry density of the sand exceeds 1.74 Mg/m3. Note.

Advice should be sought from BRRL if a locally available replacement for the Leighton Buzzard sand is used and the replacement does not achieve a mean dry density of 1.74 Mg/m3.

4.5.3.3

Calibration of operator. Before being allowed to carry out the test the operator must practise with the apparatus in order to achieve the correct downward pressure required in the test. The downward force, including that resulting from the mass of the hammer and tamper should be 300-400 N. This force is sufficient to prevent the hammer bouncing up and down on the soil. The correct force can be determined by standing the hammer, without vibration, on a platform scale and pressing down until a mass of 30-40 kg is indicated. With experience the pressure to be applied can be judged, but an occasional check on the platform scale is advisable. If the hammer-supporting frame is used, the hand pressure required is much less but should be carefully checked.

4.5.5

Sample preparation. The procedure to be adopted depends on the grading zone into which the sample falls (see Table 4.2.1), and whether the soil is susceptible to crushing. Full details of sample preparation methods are given in Tables 4.2.2 to 4.2.5. The quantities of soil required are indicated in Table 4.2.1.

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Chapter 4 Dry Density – Moisture Content Relationship 4.5.6

Standard Test Procedures

Preparation of apparatus. See that the component parts of the mould are clean and dry. Assemble the mould, base-plate and collar securely, and weigh to the nearest 5 g (m1). Measure the internal dimensions of the assembly to 0.5 mm and calculate the internal volume. The nominal dimensions of the mould give an area of cross-section of 18, 146 mm2 and a volume of 2304.5 cm3 (say 2305 cm3) but these may change slightly with wear. The inside height of the mould with collar is recorded (h 1 mm). It is particularly important to ensure the lugs and clamps holding the mould assembly together are secure and in good condition, in order to withstand the effects of vibration. If the mould has screw-on fittings, the threads must be kept clean and undamaged. Avoid cross-threading when fitting the base-plate and extension collar, and make sure that they are tightened securely as far as they will go without leaving any threads exposed. Screw threads and mating surfaces should be lightly oiled before tightening. Ensure that the vibrating hammer is working properly, in accordance with the manufacturer’s instructions. See that it is properly connected to the mains supply, and that the connecting cable is in sound condition. The supporting frame if used, must move freely without sticking. The hammer should have been verified as described in 4.5.3.3. The tamper stem must fit properly into the hammer adapter, and the foot must fit inside the CBR mould with the necessary clearance (3.5 mm all round).

4.5.7

Test procedure

4.5.7.1

Place the mould assembly on a solid base, such as a concrete floor or plinth. If the test is to be performed out of doors because of noise and vibration problems place the mould on a concrete paved area, not on unpaved ground or on thin asphalt. Any resilience in the base results in inadequate compaction.

4.5.7.2

For soils susceptible to crushing, prepare the soil to provide a sample of about 40 kg from which 5 (or more) separate batches of about 8 kg are obtained and made up to different moisture contents. It is not necessary, for soils not susceptible to crushing, to be divided into 5 separate batches. Add a quantity of soil to the mould, such that after compaction the mould is one-third filled. A preliminary trial may be necessary to ascertain the correct amount of soil. A disc of polyethylene sheet, of a diameter equal to the internal diameter of the mould, may be placed on top of the layer of soil. This will help to prevent sand particles moving up through the annular gap between the tamper and the mould.

4.5.7.3

Compact the layer with the vibrating hammer, fitted with the tamper for 60±2 s, applying a firm pressure vertically downwards throughout. The downward force of 300-400 N should only be applied by a practised operator (see 4.5.4 above). Repeat the above compaction procedure with a second layer of soil, and then with a third layer. The final thickness of the compacted specimen should be between 127 mm and 133 mm: if it is not, remove the soil and repeat the test.

4.5.7.4

After compaction remove any loose material from the surface of the specimen around the edge of the mould collar. Lay the straight-edge across the top of the collar, and measure down to the surface of the specimen with the steel rule or depth gauge, to an accuracy of 0.5 mm. Take readings at four points spread evenly over the surface, all at least 15 mm from the side of the mould. Calculate the average depth (h2 mm). The mean height of the compacted specimen, h, is given by

h = (h1 - h2 ) mm MAY 2001

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Chapter 4 Dry Density – Moisture Content Relationship

Standard Test Procedures

where’ h1 = Height of mould. 4.5.7.5

Weigh the mould with the compacted soil, collar and base-plate to the nearest 5 g (m2).

4.5.7.6

Remove the soil from the mould and place on the tray. A jacking extruder makes this operation easy if fittings to suit the CBR mould are available. However, sandy and gravelly (non-cohesive) soil should not be too difficult to break up and remove by hand.

4.5.7.7

Take two representative samples in large moisture content containers for measurement of moisture content. This must be done immediately after removal from the mould, before the soil begins to dry out. The moisture content samples must be large enough to give results representative of the maximum particle size of the soil. The average of the two moisture content determinations is denoted by w%.

4.5.7.8

For soils susceptible to crushing, repeat step 4.5.7.1 to 4.5.7.7 on each batch of soil in turn. For soil not susceptible to crushing break up the material on the tray and rub it through the 20 mm or the 37.5 mm sieve if necessary, mixing with the remainder of the sample. Add an increment of water so as to raise the moisture content by 1 to 2% (150300 ml of water for 15 kg of soil). As the optimum moisture content is approached it is preferable to add water in smaller increments.

4.5.7.9

Repeat stages 4.5.7.1 to 4.5.7.8 for each increment of water added. At least five compactions should be made, and the range of moisture contents should be such that the optimum moisture content is within that range. If necessary, carry out one or more additional test at suitable moisture contents. Above a certain moisture content the soil may contain an excessive amount of free water, which indicates that the optimum condition has been passed.

4.5.8

Calculation and expression of results. The following stages apply to both the above procedures : Calculate the bulk density ρ (in kg/m3), of each compacted specimen from the equation

ρ = where,

m2 - m1 1000 Ah

m1 = mass of mould, collar and base-plate; m2 = mass of mould, collar and base-plate with soil; h = height of compacted soil specimen = h1 – h2 mm; A = circular area of the mould (in mm2).

Calculate the density, ρd (in kg/m3), of each compacted specimen from the equation

ρd =

100ρ 100 + w

where, w, is the moisture content of the soil. The results of the required calculations, as determinations of dry density and moisture content, are plotted as described in Part 4.3.6 and illustrated in Form 4.1.1 to 4.1.4. Calculations for air voids can be calculated if required as detailed in Part 4.3.6. 4.5.9

Report. The requirements for reporting are as detailed in 4.3.7.

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CHAPTER 5 STRENGTH TESTS CALIFORNIA BEARING RATIO AND DYNAMIC CONE PENETROMETER

5.1

California Bearing Ratio (CBR) Test

5.1.1

Introduction

5.1.1.1

General. The test is an empirical test which gives an indication of the shear strength of a soil. The great value of this test is that it is comparatively easy to perform and because of its wide use throughout the world, there is a vast amount of data to assist with the interpretation of results. The CBR test is essentially a laboratory test but in some instances the test is carried out on the soil in-situ.

5.1.1.2

Scope. The laboratory CBR test consists essentially of preparing a sample of soil in a cylindrical steel mould and then forcing a cylindrical steel plunger, of nominal diameter 50 mm, into the sample at a controlled rate, whilst measuring the force required to penetrate the sample. A pictorial view of the general test arrangement is shown in Figure 5.1.1. CBR values may vary from less than 1% on soft clays to over 150% on dense crushed rock samples. Preparation of remoulded samples for the CBR test can be made in several ways. However, commonly used methods are described here: (1) Static compression (2) Dynamic compaction by (a) using 2.5 or 4.5 kg rammer and (b) using vibrating hammer.

5.1.2.1

Material. The CBR test is carried out on material passing a 20mm test sieve. If soil contains particles larger than this the fraction retained on 20mm shall be removed and weighed before preparing the test sample. If this fraction is greater than 25% of the original sample the test is not applicable. The moisture content of the specimen or specimens can be adjusted as necessary following the procedure given in Chapter 4. The moisture content used is normally to the Optimum Moisture Content (OMC), but obviously this can be varied to suit particular requirements.

5.1.2.2

Mass of soil for test. When the density or air voids content of a compacted sample is specified the exact amount of soil required for the test can be calculated as described in a) or b) below. When a compactive effort is specified the mass of soil can only be estimated, as described in c) below. a) Dry density specification. The mass of soil m1 (in g), required to just fill the CBR mould of volume Vm (in cm3) is given by the equation

m1 =

Vm (100 + w ) ρ d 100

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where, w is the moisture content of the soil (in %); and pd is the specified dry density (in Mg/m3). b) Air voids specification. The dry density, ρ d, (in Mg/m3), corresponding to an air voids content of Va (in %) is given by the equation

Va 100 ρd = 1 w + ρ s 100 ρ w 1-

Where, Va is the air voids expressed as a percentage of the total volumes of soil ; 3 ρ s is the particle density (in Mg/m ); w is the soil moisture content (in %); 3 ρ w is the density of water (in Mg/m ), assumed equal to 1. The corresponding mass of soil to just fill the CBR mould is calculated from the equation in (a) above. c) Compactive effort specification. About 6kg of soil shall be prepared for each sample to be tested. The initial mass shall be measured to the nearest 5g so that the mass used for the test sample can be determined after compaction by difference, as a check. Note.

Preliminary trials may be necessary to determine the required mass more closely.

5.1.2.3

Undisturbed samples. This method is very useful for testing of fine-grained cohesive soils, but cannot be applied to non-cohesive materials or materials containing gravel or stones. Only the CBR moulds as described in 5.1.2.4(b) are suitable for undisturbed sampling.

5.1.2.4

Apparatus. The following apparatus is variously required to carry out the 2.5 kg, 4.5 kg and Vibrating hammer methods in Figure 5.1.2. a) Test sieves of aperture sizes 20 mm and 5 mm. b) A cylindrical, corrosion-resistant, metal mould, i.e. the CBR mould, having a nominal internal diameter of 152±0.5 mm. The mould shall be fitted with a detachable base-plate and a removable extension. The mould is shown in Figure 4.3.3. The internal faces shall be smooth, clean and dry before each use. c) A compression device (load press) for static compaction, (for 2.5 kg hammer). Horizontal platens shall be large enough to cover a 150mm diameter circle and capable of a vertical separation of not less than 300 mm. The device shall be capable of applying a force of at least 300 kN. d) Metal plugs, 152±0.5 mm in diameter and 50±1.0 mm thick, for static compaction of a soil specimen (for 2.5 kg hammer). A handle which may be screwed into the plugs makes removal easier after compaction. The essential dimensions are shown in Figure 5.1.3. Three plugs are required for 2.5 kg hammer.

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50± 1

e) A metal rammer, (for 4.5 kg hammer). This shall be either the 2.5 kg rammer or the 4.5 kg rammer, both as specified in Chapter 4, depending on the degree of compaction required. A mechanical compacting apparatus may be used provided that it also complies with the requirements of that document. f) An electric, vibrating hammer and tamper, as specified in Chapter 4 (for vibrating hammer). g) A steel rod, about 16mm in diameter and 600 mm long. h) A steel straightedge, e.g. a steel strip about 300 mm long, 25 mm wide and 3mm thick, with one beveled edge. i) A spatula. j) A balance, capable of weighing up to 25 kg readable to 5 g. k) Apparatus for moisture content determination, as described in Chapter 3. l) Filter papers, 150 mm in diameter, e.g. Whatman No. 1 or equivalent.

Screw thread ∅ 150±0.5

Figure 5.1.3 Plug for use with cylindrical mould in the CBR test (in mm). 5.1.2.5

Preparation of test sample using static compression 1. Preparation of mould a) Weigh the mould with baseplate attached to the nearest 5 g (m2). b) Measure the internal dimensions to 0.5 mm c) Attach the extension collar to the mould and cover the base-plate with a filter paper. d) Measure the depth of the collar as fitted, and the thickness of the spacer plug or plugs, to 0.1 mm. 2. Preparation procedure a) This procedure is for 2.5 kg hammer in Figure 5.1.2. b) Divide the prepared quantity of soil into three portions with a mass equal to within 50 g of each other and seal each portion in an airtight container until required for use. c) Place one portion in the mould and level the surface. Compact to 1/3 the height of the mould in the compression device using suitably marked steel spacer discs to obtain the required depth of sample (127/3 = 42 mm). The mould is then removed from the compression device and the second portion of the material is added. This is then compressed to give a total sample depth to 2/3 the height of the mould (i.e. 85 mm). Finally, the remainder of the sample is MAY 2001

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added and the mould is returned to the compression device until the finished sample is just level with the top of the mould. Care should be taken not to damage the press by attempting to crush the steel mould when the sample is level : always pay close attention to the load gauge. Except for some dense aggregates the force required for compaction should not be very large. d) On completion of compaction weigh the mould, soil and base-plate to the nearest 5 g (m3). e) Unless the sample is to be tested immediately, seal the sample (by screwing on the top plate if appropriate) to prevent loss of moisture. With clay soils or soils in which the air content is less than 5%, allow the sample to stand for at least 24 h before testing to enable excess pore pressures set up during compression to dissipate. 5.1.2.6

Preparation of sample using dynamic compaction 1. General. This method may be used if a static compression device is not available. If it is required to compact specimens to a density and moisture content other than Maximum Dry Density and Optimum Moisture Content, it is preferable to use static compaction, as with dynamic compaction these can only be achieved by trial and error. Note.

An alternative to compacting a single sample using a specified compaction method (see 5.1.2.6(3) below) and then carrying out a CBR test on it, is to carry out a CBR test on each of the specimens made up during a normal compaction test (in CBR moulds). This procedure gives a curve of varying CBR with moisture content/dry density, an example is shown in Figure 5.1.8 at the end of this document.

2. Preparation of mould. Follow the procedure given in 5.1.2.5(1) above, with the exception of 5.1.2.5(1)(d) . 3. Preparation procedure 3A.

Using compaction rammers a) This procedure is for 4.5 kg hammer in Figure 5.1.2 b) The procedures for use in the CBR mould are summarised in Table 5.1.1 below. Table 5.1.1 Dynamic compaction procedures for use in CBR mould Test Method

2.5 kg rammer method Intermediate compaction * 4.5 kg rammer method Vibrating hammer method

Mass of Rammer (Kg) 2.5 4.5 4.5 **

Height of Drop mm

Number of Layers

300 450 450 -

3 5 5 3

Blows per Layer 62 30 62 -

* Recommended procedure to obtain a specimen density between that achieved by using the 2.5 kg and 4.5 kg rammer methods. ** See Chapter 4 for specification of vibrating hammer c) Having decided which compaction method to use from Table 5.1.2, divide the prepared quantity of soil into three (or five) portions with a mass equal to

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d) e)

f) g) h) i) 3B.

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within 50 g of each other and seal each portion into an airtight container until required for use. Stand the mould assembly on a solid base, e.g. a concrete floor. Place the first portion of soil into the mould and compact it with the required number of blows of the appropriate rammer. After compaction the layer should occupy about or a little more than one-third (or one-fifth) of the height of the mould. Ensure that the blows are evenly distributed over the surface of the soil. Repeat the process in (e) above using the other two (or four) portions of soil, so that the final of the soil surface is not more that 6mm above the top of the mould body. Remove the collar, trim the soil flush with the top of the mould with a scraper, and check with the steel straightedge that the surface is level. Weigh the mould, soil and base-plate to the nearest 5 g (m3) Seal and store the sample as described in 5.1.2.5(2)(e)

Using a vibrating hammer a) This procedure is for Vibrating Hammer in Figure 5.1.2. b) Divide the prepared quantity of soil into three portions with a mass equal to within 50 g of each other and seal each portion in an airtight container until required for use, to prevent loss of moisture. c) Stand the mould assembly on a solid base, e.g. a concrete floor or plinth. d) Please the first portion of soil into the mould and compact it using the vibrating hammer fitted with the circular steel tamper. Compact for a period of 60±2 s, applying a total downward force on the sample of between 300 N and 400 N. The compacted thickness of the layer shall be about equal to or a little greater than one-third of the height of the mould. e) Repeat 3B(d) of 5.1.2.6(3) above using the other two portions of soil in turn, so that the final level of the soil surface is not more than 6 mm above the top of the mould. f) Remove the collar and trim the soil flush with the top of the mould with the scraper, checking with the steel straightedge. g) Weigh the mould, soil and base-plate to the nearest 5 g (m3). h) Seal and store the sample as described in 5.1.2.5(2)(e) above.

3C.

Preparation of undisturbed sample. Take an undisturbed sample from natural soil or from compacted fill by the procedure described in Chapter 2 using a weighed CBR mould fitted with a cutting shoe. After removing the cutting shoe from the mould, cut and trim the ends of the sample so that they are flush with the ends of the mould body. Fill any cavities with fine soil, well pressed in. Attach the base-plate and weigh the sample in the mould to the nearest 5 g (m3). Unless the sample is to be tested immediately, seal the exposed face with a plate or an impervious sheet to prevent loss of moisture.

5.1.2.7

Soaking 1.

General. The test sample as prepared will normally represent the material shortly after compaction in the road works. However, if the material is likely to be subjected to an increase in moisture content, either from rainfall, ground-water or ingress through the surfacing it is probable that its strength and, hence, CBR, will drop as the moisture content increases. In an attempt to estimate these effects CBR samples can be soaked in water for 4 days prior to penetration testing.

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Some soils, especially heavy clays, are likely to swell during soaking and excessive swelling may indicate that the soil is unsuitable for use as a sub-grade; it is, therefore, important to record the swell during soaking. 2.

Apparatus. The following items are required in addition to the apparatus listed in 5.1.2.4 above. a) A perforated base-plate, fitted to the CBR mould in place of the normal baseplate (see Figure 5.1.4). b) A perforated swell plate, with an adjustable stem to provide a seating for the stem of a dial gauge (see Figure 5.1.4). c) Tripod, mounting to support the dial gauge. A suitable assembly is shown in Figure 5.1.4. d) A dial gauge, having a travel of 25 mm and reading to 0.01 mm. e) A soaking tank, large enough to allow the CBR mould with base-plate to be submerged, preferably supported on an open mesh platform. f) Annular surcharge discs, each having a mass known to ±50 g, an internal diameter of 52-54 mm and an external diameter of 145-150 mm. As an alternative, half-circular segments may be used. For practical purposes, the latter are often easier to use. g) Petroleum jelly.

Dial Dialgauge gauge Dial gauge mounting frame Adjustable stem

Surcharge Surcharge rings rings Extension collar Extension collar

Looking nut

Sooking tank

Perforated swell plate CBR mould body Sample

Perforated baseplate Open mesh platform

Figure 5.1.4 3.

Apparatus for measuring the swelling of a sample during soaking for the CBR Test. Test procedure a) Remove the base-plate from the mould and replace it with the perforated base-plate. b) Fit the collar to the other end of the mould, packing the screw threads with petroleum jelly to obtain a watertight joint. c) Place the mould assembly in the empty soaking tank. Place a filter paper on top of the sample, followed by the perforated swell plate. Fit the required number of annular surcharge discs around the stem on the perforated plate. Note. One surcharge disc of 2 kg simulates the effect of approximately 70 mm of superimposed construction on the sub-grade being tested. However, the exact amount of surcharge is not critical. Surcharge discs of any convenient multiples may be used.

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d) Mount the dial gauge support on top of the extension collar, secure the dial gauge in place and adjust the stem on the perforated plate to give a convenient zero reading (see Figure 5.1.4) e) The apparatus is then placed in a tank of clean water and the sample is kept submerged for 4 days and the dial gauge is read every 24 hours. The difference between the initial and final dial gauge reading gives the swell, S. The % swell is given by :

% Swell =

S S x 100 = % 127.0 1.27

Where, S is in mm. f)

On completion of soaking surplus water is wiped from the sample which is reweighed. The difference in weights before and after soaking is the weight of water absorbed, Ww. The % of water absorbed is give by :

% Water absorbed =

M W (100 + m 2 ) % Wm

Where Wm is original weight of sample and m2 is original moisture content. g) Take off the dial gauge and its support, remove the mould assembly from the immersion tank and allow the sample to drain for 15 min. If the tank is fitted with a mesh platform leave the mould there to drain after emptying the tank. If water remains on the top of the sample after draining it should be carefully siphoned off. h) Remove the surcharge discs, perforated plate and extension collar. remove the perforated base-plate and refit the original base-plate. i) Weigh the sample with mould and base-plate to the nearest 5 g if the density after soaking is required. j) If the sample has swollen, trim it level with the end of the mould and reweigh. k) The sample is then ready for test in the soaked condition. 5.1.2.8

Penetration test procedure 1.

Apparatus. A general arrangement of apparatus is shown in Figure 5.1.5. The apparatus consists of: a) A cylindrical metal plunger, the lower end of which shall be of hardened steel and have a nominal cross-sectional area of 1935 mm2, corresponding to a specified diameter of 49.65 ±0.10 mm. A convenient size would be approximately 250 mm long. b) A machine for applying the test force through the plunger, having a means for applying the force at a controlled rate. The machine shall be capable of applying at least 45 kN at a rate of penetration of the plunger of 1 mm/min to within ±0.2 mm/min. c) A calibrated force-measuring device, usually a load ring or proving ring. The device shall be supported by the cross-head of the compression machine so as to prevent its own weight being transferred to the test specimen (see Figure 5.1.1) Note. At least three force-measuring devices should be available, having the following ranges : 0 to 2 kN readable to 2 N for values of CBR up to 8% 0 to 10 kN readable to 10 N for values of CBR from 8% to 40% MAY 2001

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0 to 50 kN readable to 50 N for values of CBR above 40% d) A means of measuring the penetration of the plunger into the specimen, to within 0.01 mm. A dial gauge with 25 mm travel, reading to 0.01 mm and fitted to a bracket attached to the plunger is suitable. A general arrangement is shown in Figure 5.1.5. A dial gauge with a chisel edge to the stem anvil is easier to use than one with a pointed stem anvil. Note. A dial gauge indicating 1 mm/revolution is convenient since the specified rate of penetration of 1 mm/min can be controlled conveniently by keeping the hand of the dial gauge in step with the second hand of a clock or watch. This is particularly convenient when using a non-motorised loading frame. e) A stop-clock or stopwatch readable to 1 s. f) The CBR mould as described in Chapter 4. g) Surcharge discs as described in 5.1.2.7(2). 2.

Procedure a) Place the mould with base-plate containing the sample, with the top face of the sample exposed, centrally on the lower platen of the testing machine. b) Place the appropriate annular surcharge discs on top of the sample. c) Fit into place the cylindrical plunger and force-measuring device assembly with the face of the plunger resting on the surface of the sample. Make sure that the proving ring dial gauge is properly adjusted, i.e. that there is no daylight between the bottom of the stem and the proving ring anvil. Note. It may be necessary to move the crosshead up to allow the plunger to be inserted through the surcharge discs and the stabilizer bar (if fitted). Be careful to lower the cross-head again in order to make sure that the lower platen and penetration dial gauge have enough travel left before starting the test. This must be level before starting the penetration test. d) Apply a seating force to the plunger, depending on the expected CBR value, as follows: For CBR value up to 5% apply 10 kN For CBR value from 5% to 30%, apply 50 kN For CBR value up to 30% apply 250 kN Note. The number of proving ring dial gauge divisions corresponding to the required seating load can be found from the calibration chart for that proving ring. It is helpful to have the N/division value displayed on each load ring. It is extremely important to ensure that the maximum allowable dial gauge reading for the proving ring is never exceeded. e) Record the reading of the force-measuring device as the initial zero reading (because the seating force is not taken into account during the test) or reset the force measuring to read zero. f) Secure the penetration dial gauge in position. Record its initial zero reading, or reset it to read zero. Make sure that all connections between plunger, crosshead, proving ring and penetration dial gauge assembly are tight. g) Start the test so that the plunger penetrates the sample at the uniform rate of 1±0.2 mm/min, and at the same instant start the timer. MAY 2001

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h) Record readings of the force gauge at intervals of penetration of 0.25 mm to a total penetration not exceeding 7.5 mm (see Form 5.1.2). Note. If the operator plots the force penetration curve as the test is being carried out, the test can be terminated when the indicated CBR value falls below its maximum value. Thus if the CBR at 2.5 mm were seen to be 6% but by 3.5 mm penetration it could be seen to have fallen below 6%, the test could be stopped and the result reported as: CBR at 2.5 mm penetration = 6% CBR at 5.0 mm penetration = <6%

Dial gauge support

Dial gauge 25 travel (0.01divisions 1per revolution)

Surcharge rings

Detachable collar

Hardened steel end Soil Sample 152x 127 high

49.65 0.1 Timer Mould

All dimensions are in millimetres. This design has been found satisfactory, but alternative designs may be used provided that the essential requirements are fulfilled.

Figure 5.1.5

General arrangement of apparatus for the CBR test

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i) If a test is to be carried out on both ends of the sample, raise the plunger and level the surface of the sample by filling in the depression left by the plunger and cutting away any projecting material. Check for flatness with the straightedge. j) Remove the base-plate from the lower end of the mould, fit it securely on the top end and invert the mould. Trim the exposed surface if necessary. If the sample is to be soaked make sure that a perforated base-plate is used in the correct position. k) If the sample is to be soaked before carrying out a test on the base follow the procedure described in 5.1.2.7(3) above. l) Carry out the penetration test on the base by repeating 5.1.2.8(2). m) After completing the penetration test or tests, determine the moisture content of the test sample as follows: (a) For a cohesive soil containing no gravel-sized particles and before extruding the sample from the mould, take a sample of about 350 g from immediately below each penetrated surface, but do not include filling material used to make up the first end tested. Determine the moisture content of each sample. Note.

If the sample has been soaked the moisture content after soaking will generally exceed the initial moisture content. Because of the possibility of moisture gradients the determination of dry density from the moisture content after soaking may have little significance. If required, the dry density after soaking can be calculated from the initial sample mass and moisture content and the measured increase in height due to swelling.

(b) For a cohesionless soil or a cohesive soil containing gravel-sized particles, extrude the complete sample, break it in half and determine the moisture contents of the upper and lower halves separately. 5.1.2.9

Calculation and expression of results 1.

Force-penetration curve a) Calculate the force applied to the plunger from each reading of the forcemeasuring device observed during the penetration test. Note. Alternatively, readings of the force-measuring device may be plotted directly against penetration readings. Forces are then calculated only at the appropriate penetration values as in 5.1.2.6(1)(c). b) Plot each value of force as ordinate against the corresponding penetration as abscissa and draw a smooth curve through the points. The normal type of curve is convex upwards as shown by the curve labeled Test 1 in Figure 5.1.6 and needs no correction. If the initial part of the curve is concave upwards as for Test 2 (curve OST) in Figure 5.1.6, the following correction is necessary. Draw a tangent at the point of greatest slope, i.e. the point of inflexion, S, and produce it to intersect the penetration axis at Q. The corrected curve is represented by OST, with its origin at Q from which a new penetration scale can be marked.

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If the graph continues to curve upwards as for Test 3 in Figure 5.1.6, and it is considered that the penetration of the plunger is increasing the soil density and therefore its strength, the above correction is not applicable. c) Calculation of California Bearing Ratio. The standard force-penetration curve corresponding to a CBR value of 100% is shown by the heavy curve in Figure 5.1.7, and forces corresponding to this curve are given in Table 5.1.2. The CBR value obtained from a test is the force read from the test curve (after correction and calculation if necessary) at a given penetration expressed as a percentage of the force corresponding to the same penetration on the standard curve. Curve representing a range of CBR values is included in Figure 5.1.7. Penetrations of 2.5mm and 5mm are used for calculating the CBR value. From the test curve, with corrected penetration scale if appropriate, read off the forces corresponding to 2.5 mm and 5 mm penetration. Express these as a percentage of the standard force at these penetrations, i.e. 13.2 kN and 20 kN respectively. Take the higher percentage as the CBR value. If the force-penetration curve is plotted on a diagram similar to Figure 5.1.7 the CBR value at each penetration can be read directly without further computation if the correction described in 5.1.2.9(1)(b) for test 2 is not required. The same diagram can be used for small forces and low CBR values if both the force scale (ordinate) and the labeled CBR values (abscissa) are divided by 10 as shown in brackets in Figure 5.1.7. Table 5.1.2 Standard force-penetration relationships for 100% CBR Penetration Force mm kN kgf* 2 11.5 1172 2.5 13.2 1345 4 17.6 1793 5 20.0 2038 6 22.2 2262 8 26.3 2680 *Standard force in kilonewton converted using factor of 9.807 Note. Older equipment may be calibrated in imperial units, in which case

2.

CBR at 0.1 inches penetration =

Test load (1bf) x 100% 3000

CBR at 0.2 inches penetration =

Test load (1bf) x 100% 4500

Density calculations a) Determine the internal volume of the mould, Vm (in cm3). b) Bulk density. The initial bulk density, ρ (in kg/m3), of a sample compacted with a specified effort (preparation methods 4.5 kg and vibrating hammer); see Figure 5.1.2, or of an undisturbed sample, is calculated from the equation:

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ρ =

Standard Test Procedures

m3 - m 2 Vm

where, m3 is the mass of soil, mould and base-plate (in g); m2 is the mass of the mould and base-plate (in g); Vm is the volume of the mould body (in cm3), c) Dry density. The initial dry density, ρ d (in kg/m3 ), of the sample is calculated from the equation :

 100  ρd =  ρ  100 + w  where, w is the moisture content of soil (in %). If the dry density, ρ ds from the equation:

(in Mg/m3), of the soaked soil is required, calculate it

ρd

ρ ds = 1 +

Ax 1000 Vm

where, A is the area of cross section of the mould (in mm2) x is the increase in sample height after swelling (in mm). Examples of completed calculations are given in Forms 5.1.1, 5.1.2 and 5.1.3. 5.1.2.10 Report. The test report shall affirm that the test was carried out in accordance with this Part of this standard. The results of tests on the top and bottom ends of the sample shall be indicated separately. The test report shall contain the following information: a) the method of test used; b) force-penetration curves, showing corrections if appropriate; c) the California Bearing Ratio (CBR) values, to two significant figures. If the results from each end of the sample are within ±10% of the mean value, the average result may be reported; d) the initial sample density and the moisture content and dry density if required; e) the method of sample preparation; f) the moisture contents below the plunger at the end of each test, or the final moisture contents of the two halves of the sample; g) whether soaked or not, and if so the period of soaking and the amount of swell. h) the proportion by dry mass of any over-size material removed from the original soil sample before testing; i) information on the description and origin of the sample, as detailed on the test forms.

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5.2

Dynamic Cone Penetrometer (DCP) Test

5.2.1

General. The dynamic cone penetrometer (DCP) test was developed by Transport and Road Research Laboratory (TRRL), England. The DCP is an instrument designed for the rapid in-situ measurement of the structural properties of existing road pavements constructed with unbound materials. It is also used for determining the in-situ CBR value of compacted soil sub-grade beneath the existing road pavement. Continuous measurements can be made down to a depth of 800 mm or, when an extension rod is fitted, to a depth of 1200 mm. Where pavement layers have different strengths the boundaries can be identified and the thickness of the layers determined. Correlations have been established between measurements with DCP and California Bearing Ratio (CBR) so that results can be interpreted and compared with CBR specifications for pavement design. Agreement is generally good over most of the range but differences are apparent at low values of CBR, especially for fine-grained materials. A typical test takes only a few minutes and therefore the instrument provides a very efficient method of obtaining information which would normally require the digging of test pits.

5.2.2

Apparatus. The DCP uses an 8kg weight dropping through a height of 575 mm and a 60" cone having a diameter of 20mm. The apparatus is assembled as shown in Figure 5.2.1. It has the following parts : a) b) c) d) e) f) g) h) i)

Handle Top Rod Hammer (8kg) Anvil Handguard Cursor Bottom Rod 1 Meter rule 60o Cone Spanners and tommy bar are used to ensure that the screwed joints are dept tight at all times.

The following joints should be secured with loctite or similar non-hardening thread locking compound prior to use : (i) Handle/top rod (ii) Anvil/bottom rod (iii) Bottom rod/cone 5.2.3

Procedure a) After assembly, the zero reading of the apparatus is recorded. This is done by standing the DCP on a hard surface, such as concrete, checking that it is vertical and then entering the zero reading in the appropriate place on the proforma (Form 5.2.1).

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Standard Test Procedures

1960 mm APPROX

Chapter 5 California Bearing Ratio & Dynamic Cone Penetrometer

600 INC

Figure 5.2.1 Dynamic cone penetrometer assembly

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b) The instrument is held vertical as shown in Figure 5.2.2 and the weight carefully raised to the handle. Care should be taken to ensure that the weight is touching the handle, but not lifting the instrument, before it is allowed to drop and that the operator lets it fall freely and does not lower it with his hands. Note.

If during the test the DCP leaves the vertical no attempt should be made to correct this as contact between the bottom rod and the sides of the hole will give rise to erroneous results.

c) It is recommended that a reading should be taken at increments of penetration of about 10mm. However, it is usually easier to take a scale reading after a set number of blows. It is therefore necessary to change the number of blows between readings according to the strength of the layer being penetrated. For good quality granular bases readings every 5 or 10 blows are normally satisfactory but for weaker sub-base layers and sub-grades readings every 1 or 2 blows may be appropriate. Note.

There is no disadvantage in taking too many readings, however if readings are taken too infrequently, weak spots may be missed and it will be more difficult to identify layer boundaries accurately, hence important information will be lost.

d) After completing the test the DCP is removed by gently tapping the weight upwards against the handle. Care should be taken when doing this as if it is done too vigorously the life of the instrument will be reduced. Note 1.

Penetration rates as low as 0.5 mm/blow are acceptable but if there is no measurable penetration after 20 consecutive blows it can be assumed that the DCP will not penetrate the material. Under these circumstances a hole can be drilled through the layer using an electric or pneumatic drill or by coring. The lower layer can then be tested in the normal way. If only occasional difficulties are experienced in penetrating granular materials it is worthwhile repeating any failed tests a short distance away from the original test point.

2) Cone should be replaced when its diameter is reduced by 10 percent. 5.2.4

Calculation and expression of results. The results of the DCP test are usually recorded on a field data sheet similar to that shown in Form 5.2.1. The results can then either be plotted by hand Figure 5.2.3 or processed by computer. The boundaries between layers are easily identified by the change in the rate of penetration. The thickness of the layers can usually be obtained to within 10 mm except where it is necessary to core (or drill holes) through strong materials to obtain access to the lower layers. In these circumstances the top few millimeters of the underlying layer is often disturbed slightly and appears weaker than normal. Relationship between the DCP readings and CBR can be obtained by the following equation:

DCP - CBR percent =

3700 (Pen 5 )1.3

The Pen 5 = Penetration in mm, every 5 blow interval. Relationship between the DCP reading and the CBR can also be found from Kleyn and Van Hearden graph as shown in Figure 5.2.4.

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Figure 5.2.2 Dynamic Cone Penetrometer in Action

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5.2.5 Report. The test report shall contain the following information : a) The method of test used b) Data sheet shall be included (Form 5.2.1) c) Blows - Penetration depth curve (Figure 5.2.3) and CBR (%) value. All other necessary information, needed by the client, should be added

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Form 5.2.1

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Chapter 6 Determination of In-situ Density

Standard Test Procedures

CHAPTER 6 DETERMINATION OF IN-SITU DENSITY

6.1

Introduction In-situ density is widely used to control the field compaction of earthworks and pavement layers. There are a number of methods available for measuring in-situ density but only the two common methods are considered here. These are the corecutter method and the sand replacement method.

6.2

Sand Replacement Method

6.2.1

Introduction. The sand replacement method is the most widely used in-situ density test. Although the test takes slightly longer to perform than some other in-situ density tests, the test may be carried out on most type of materials. There are various types of sand replacement equipment in use, but all types have the following essential features. a) b) c) d)

A sand container or bottle A valve to start or stop the flow of sand A core connected to the valve and intended to fit over the area being tested. A base plate which acts as a template during the excavation of the soil.

The stated size of the pouring cylinder relates to the diameter of the cone and thus the diameter of the hole to be excavated. The three sizes commonly available are 100 mm, 150 mm and 200 mm. The 100mm apparatus is mainly used for fine grained soils as used for earthworks and the 200mm apparatus is intended for coarse grained materials as used in the sub-base and base layers. 6.2.2

Apparatus. The following apparatus is required for the test : a) A pouring cylinder (Small or Large) (see Figure 6.2.1.) b) Suitable tools for excavating holes in compacted soil (bent spoon, scraper tool, hammers, chisels and paint brush) c) Cylindrical metal calibrating container with an internal diameter of 200±5 mm and internal depth of 250 mm fitted with a lip about 75 mm wide and about 5 mm thick surrounding the open end for large pouring cylinder and internal diameter 100±2 mm and internal depth of 150±3 mm fitted with a lip about 50 mm wide and about 5 mm thick is required (see Figure 6.2.2). d) Balance, readable to 10g for the large pouring cylinder method, or readable to 1 g for the small pouring cylinder method. e) Glass plate of 10mm thick and about 500mm square. f) Metal trays or containers g) Apparatus for moisture content determination h) A metal tray about 500mm square and about 50mm deep with a 200mm diameter hole in the centre for large pouring cylinder and about 300mm square and about 40mm deep with a 100mm diameter hole in the centre. i) Clean closely graded, preferably with rounded grains replacement sand. (100% passing 600µm sieve and 100% retained on the 75µm sieve).

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6.2.3

Calibrations

6.2.3.1

Calibration of apparatus. When the apparatus is used for a test a certain amount of sand is contained in the cone above the excavated hole. This weight of sand must be deducted from the total weight of sand used in the test in order to determine the exact weight of sand used to fill the hole. The apparatus must then be calibrated to determine the weight of sand in the cone. As the weight of sand in the cone will vary slightly with the type of sand used, calibration of the apparatus should take place each time the sand is calibrated. One minor complication is that generally the base-plate is left in place during the test and a small amount of sand is retained between the base-plate and the cone. In this case, the calibration of the apparatus should be carried out using both base-plate and cone. It is not normal to use the base-plate when calibrating the sand so, in this case, the calibration of the apparatus should be done with the cone only. To calibrate the apparatus, it is partly filled with sand and weighed. The apparatus (with base-plate if required) is then placed on a flat glass plate and the valve is opened. When the cone is completely full of sand, the valve is closed and the apparatus is re-weighed. The difference between the two weights is the weight of sand in the cone and base-plate if used. The calibration is normally repeated three times and the average value taken.

6.2.3.2

Calibration of sand. The sand should be stored in a clean container and protected from rain and damp and should be airtight. The purpose of the calibration is to determine the density of the sand being used. Each new batch of sand should be calibrated before use and existing sand should be calibrated weekly or monthly depending on the frequency of use. The calibrating container is of the same diameter as the apparatus being used and has a depth similar to that of the hole excavated for the test. To use the container, fill the apparatus first with sand and weigh it. Then place the cone over the calibration container and open the valve to allow the sand to fill the cone and the container. When the cone is completely full close the valve and reweigh the apparatus. The difference between these two weights is the weight of sand in the container plus the weight of sand in the cone. The weight of sand in the cone is found from the calibration of apparatus and may be deducted from the total weight of sand to give the weight of sand in the container. The container is then emptied, weighed and then filled with clean water. Wipe off any surplus water on the sides of the containers with a clean cloth and reweigh the container plus water. The weight of water in the container and thus its volume are then determined. Repeat these measurements at least three times and calculate the mean values.

6.2.4.

Excavation of test hole

6.2.4.1

Preparation of surface. Expose a flat area, approximately 600mm square (approximately 450mm square for the small cylinder method) of the soil to be tested and trim it down to a level surface. Brush away any loose material which is not part of that being tested. The surface should be as level as possible in order to reproduce the laboratory calibration conditions.

6.2.4.2

Excavation procedure 1) Lay the metal tray on the prepared surface with the hole over the portion of the soil to be tested. Run a trowel or other sharp tool around the outside of the tray, marking square on the surface of the soil being tested. This will help to position the pouring cylinder during the later stages of the test. It is often helpful for the tray to be nailed to the ground to stop it moving during the excavation of the test hole. MAY 2001

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2) Using the hole in the metal tray as a pattern, excavated a round hole, approximately 200 mm in diameter (100 mm for the small cylinder method) and the depth of the layer to be tested up to a maximum of 250 mm deep (150 mm for the small cylinder method). Do not leave loose material in the hole and do not distort the immediate surround to the hole. Carefully collect all the excavated soil from the hole and determine its mass, mw to the nearest 10g (1 g for the small cylinder method). Remove the metal tray before placing the pouring cylinder in position over the excavated hole. Note.

Take care in excavating the hole to see that the hole is not enlarged by levering the excavating tool against the side of the hole, as this will result in lower densities being recorded.

3) Place a representative sample of the excavated soil in an airtight container and determine its moisture content, w. Alternatively, the whole of the excavated soil shall be dried and its mass md, determined. 4) Place the pouring cylinder filled with the constant mass of sand (m1) so that the base of the cylinder covers the hole concentrically. This is assisted by the square previously marked around the tray. Keep the shutter on the pouring cylinder closed during this operation. Open the shutter and allow sand to run out; during this period do not vibrate the pouring cylinder or the surrounding area. When no further movement of the sand takes place, close the shutter. Remove the cylinder and determine the mass of sand remaining in it (m4) to the nearest 10 g (nearest 1 g for the small cylinder method). For the small cylinder method this is easily done by weighing the cylinder and remaining sand together. 6.2.5

Calculation and expression of results

6.2.5.1

Calculations 1) Calculate the mass of sand required to fill the calibrating container, ma (in g), from the equation: ma = m1 - m3 - m2 where m1 is the mass of [cylinder and] sand before pouring in the calibrating container (in g) : m2 is the mean mass of sand in cone (in g); m3 is the mean mass of [cylinder and] sand after pouring into the calibrating container (in g). 2) Calculate the bulk density of the sand. ρa (in Mg/m3), from the equation :

ρ

ρ a = ma V

where, V is the volume of the calibrating container (in mL).

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3) Calculate the mass of sand required to fill the excavated hole, mb (in g). from the equation: mb = m1 - m4 - m2 where, m1 is the mass of [cylinder and] sand before pouring in the hole (in g) : m2 is the mean mass of sand in the cone (in g); m4 is the mean mass of [cylinder and] sand after pouring into the hole (in g) 4) Calculate the bulk density of the soil. ρ (in mg/m3). from the equation:

m  ρ =  w  ρa  mb  where mw is the mass of soil excavated (in g); mb is the mean mass of sand required to fill the hole (in g); ρa is the bulk density of the sand (in Mg/m3). 5) Calculate the dry density, ρd (in Mg/m3), from the equation:

ρd =

100 ρ 100 + w

where, w is the moisture content of the soil (in %). 6) Calculate the in-situ relative compaction (RC) of the tested layer from the equation :

RC =

ρd x 100% MDD

where, MDD is the Maximum Dry Density obtained from the compaction test used as the standard for the particular layer. Note that the type of compaction test used is dependent on the type of material. Example of completed calculations are shown in Forms 6.2.1 to 6.2.3. 6.2.6

Report. The correct test form must be used for the report. The report shall contain the following information: a) The in-situ bulk and dry densities of the soil (in Mg/m3) to the nearest 0.01 in Mg/m3. b) The moisture content. as a percentage, to two significant figures. c) All other information required by the test form. e.g. sample origin, description etc. d) The operator should sign and date the test form.

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6.3

Core Cutter Method

6.3.1

Introduction. This method is only used on fine-grained cohesive soils which do not contain stones. It is, therefore, very useful for control of earthworks and subgrade materials but is not suitable for coarse grained pavement materials. The test involves jacking or hammering a steel cylinder of known mass and volume into the soil, excavating it and finding the mass of soil contained in the cylinder.

6.3.2

Apparatus. The following apparatus is required for the test : a) Cylindrical steel core cutter. 130 mm long and of 100±2 mm internal diameter, with a wall thickness of 3mm beveled at one end, of the type illustrated in Figure 6.3.1. The cutter shall be kept lightly greased. Note.

If the average density over a smaller depth is required, then the appropriate length of cutter should be used.

b) Steel dolly, 25 mm high and of 100 mm internal diameter, with a wall thickness of 5mm, fitted with a lip to enable it to be located on top of the core cutter (see figure 6.3.1). c) Steel rammer. d) Balance, readable to 1 g. e) Palette knife, a convenient size is one having a blade approximately 200 mm long and 30 mm wide. f) Steel rule, graduated to 0.5 mm. g) Short-handled hoe, or spade, and pickaxe. h) Straightedge, e.g. a steel strip about 300 mm long 25 mm wide and 3 mm thick, with one beveled edge. i) Apparatus for moisture content determination. j) Apparatus for extracting samples from the cutter (optional). 6.3.2

Care and preparation of apparatus

6.3.2.1

Care of apparatus. The condition of the cutting edge should be frequently checked as any damage will lead to inaccuracy in the test. A badly damaged edge may be reformed on a lathe taking care to cut the new edge square to the long axis of the mould. Any repair to the cutting edge will require the mould factor to be redetermined.

6.3.3.2

Preparation of apparatus a) Calculate the internal volume of the core cutter in cubic centimetres from its dimensions which shall be measured to the nearest 0.5 mm (Vc ). b) Weigh the cutter to the nearest 1 g (mc ). c) Mould factor, To assist in the calculation of the bulk density of the soil it can be useful to calculate a mould factor for each cutter, and to stamp or paint the value F on the mould. For the size of core cutter detailed above, the mould factor ratio H calculates as 0.979. This value would be used as a multiplier for the mass of wet soil in the core cutter (in g).

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Alternatively, a mould factor can be calculated as : Mould Factor

F =

π D2 x H x x (1000) 4 (1000)3

F = 0.7854 x

D2 x H (1000) 2

Where, D is the diameter of the mould in mm. H is the height of the mould in mm. The value obtained from this calculation is used as a divisor to the mass of wet soil in the core cutter (in g). MAY 2001

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6.3.4

Test procedure

6.3.4.1

The area to be tested is first leveled and all loose material removed. The lightly greased mould with driving dolly fixed is placed in position with the cutting edge on the prepared surface.

6.3.4.2

The mould is then slowly driven into the soil by use of a jack or with a suitable rammer (see Figure 6.3.1). Take care not to rock the mould and drive the cutter until only about 10 mm of the dolly remains above the surface of the soil. The use of a jack is to be preferred as this causes least disturbance to the soil. However, some form of reaction weight such as a vehicle is required. To use a jack, a block of wood is first placed on the top of the dolly and a hydraulic or screw jack is then placed between the wood block and the underside or the reaction weight (normally a jeep). The jack is then extended so that the mould is driven squarely into the ground until only about 10mm of dolly is remaining above the surface. If driving is continued until the soil completely fills the mould and dolly, there is a danger of compressing the soil in the mould, thus giving incorrect results.

6.3.4.3

The mould, dolly and soil are then dug out of the ground using a spade. The soil in the mould should not be disturbed during this operation.

6.3.4.4

The driving dolly should then be removed from the mould and the soil protruding from each end of the mould trimmed off using a straight edge. The mould and soil are weighed, ms .

6.3.4.5

The soil in the mould is then removed, crumbled and representative samples taken for moisture content.

6.3.5

Calculation and expression of results. In principle, the bulk density of the soil. ρ ( in Mg / m 3) , is calculated from the equation :

ρ =

ms − mc Vc

where, ms is the mass of soil and core cutter (in g); mc is the mass of core cutter (in g); Vc is the internal volume of core cutter (in mL). Alternatively, using the mould factor ratio (see Chapter 4), the bulk density of the soil, ρ ( in Kg / m 3 ) , can be calculated from the equation :

ρ = ms - mc x

F H

As a second alternative, using the mould factor F, the bulk density of the soil, ρ ( in kg / m3 ) can be calculated from the equation :

ρ =

ms − mc F

Value in kg/m3 are converted to Mg/m3 by dividing by 1000. MAY 2001

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Chapter 6 Determination of In-situ Density

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Calculate the dry density, ρd (Mg/m3) from equation :

ρd =

100ρ 100 + w

where, w is the moisture content of the soil (in %). The in-situ bulk and dry densities of the soil (Mg/m3), are expressed to the nearest 0.01 Mg/m3. An example of a completed test calculation is given in Form 6.3.1 at the end of this document. 6.3.6

Report. The test report shall contain the following information : a) b) c) d) e)

the method of the test used; the in-situ bulk and dry densities of the soil in Mg/m3) to the nearest 0.01 Mg/m3 ; the moisture content, (in %), to two significant figures; all other details required by the test form regarding sample origin and description etc; the operator should sign and date the test form.

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Chapter 7 Tests For Aggregates And Bricks

Standard Test Procedures

CHAPTER 7 TESTS FOR AGGREGATES AND BRICKS

7.1

Determination of Clay and Silt Contents in Natural Aggregates

7.1.1

Scope. This test covers the determination of the amount of material finer than the 75 micron sieve by washing. Clay particles and other aggregate particles that are dispersed by the wash water, as well as water-soluble materials, will be removed from the aggregate during the test. In addition to the test which uses water only for the washing of the material, there is another test in which a dispersing agent is used in assisting the loosening of the material finer than the 75 micron sieve. Unless otherwise stated water only will be used.

7.1.2

Method outline. A sample of the aggregate is washed in a prescribed manner using water. The decanted wash water, containing dissolved and suspended material, is passed through the 75 micron test sieve. The loss in mass resulting from the wash treatment is calculated as a percentage of the original sample and is reported as the percentage of material finer than the 75 micron sieve by washing.

7.1.3

Equipment

7.1.3.1

Balance, which shall be capable of weighing a mass of aggregate appropriate to the maximum size of aggregate and accurate to 0.1 g.

7.1.3.2

Test sieves. A nest of two sieve, the lower being the 75 micron test sieve and the upper being a sieve with openings in the range of 2.36 mm to 1.18 mm.

7.1.3.3

Container, which will permit the sample with water to be vigorously agitated without any loss of aggregate or water.

7.1.3.4

Oven, of sufficient capacity to heat and maintain the temperature to 110 0C plus or minus 50C.

7.1.4

Sampling. Sampling shall be in accordance with the test method described in Chapter 2. Reduction of the bulk sample must also be carried out in order that the required mass of material for the test is obtained. After reduction, which will yield the test portion, the mass of the test portion shall comply with the values given in Table 7.1.1. Table 7.1.1

Minimum mass of test portion

Nominal maximum size of aggregate 2.36 mm 5.00 mm 10.0 mm 20.0 mm 28.0 mm 40.0 mm Larger than 63.0 mm

Minimum mass, g 100 500 1000 2500 5000 5000 5000

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7.1.5

Material finer than the 75 micron sieve test

7.1.5.1

Procedure a) Dry the test sample in the oven to constant mass at a temperature of 1100C plus or minus 50C. Determine the mass to the nearest 0.1% of the total mass of the test sample. b) Place the sample in a container and add sufficient water to cover it. No detergent, or other substance shall be added to the water. Agitate the sample and water with sufficient vigour to result in complete separation of the particles finer than 75 micron sieve from the coarser particles and to bring the fine material into suspension. The use of a large spoon or other similar instrument to stir and agitate the materials may be used. Immediately pour the wash water containing the suspended and dissolved particles over the nested sieves so arranged that the coarser sieve is at the top. Avoid decanting the coarser aggregates. c) Add a second charge of water to the sample in the container, agitate, and decant as before, the operation being repeated as many times as is necessary for the wash water to be clear. d) Return all material retained on the nested sieves by flushing to the washed sample. Dry the washed sample in the oven to constant mass at 1100C plus or minus 50C and determine the mass of the sample to the nearest 0.1% of the original mass of the sample. Note.

7.1.5.2

Following the washing of the sample and flushing any materials retained on the 75 micron sieve back into the container, no water should be decanted from the container except through the 75 micron sieve. This is to avoid any accidental loss of material. Excess water from flushing should be evaporated in the drying process.

Calculation. Calculate the amount of material passing the 75 micron sieve by washing, using the following expression: A = 100 x (B – C) / B Where, A is the percentage of material finer than the 75 micron sieve by washing. B is the original dry mass of sample in grams. C is the dry mass of sample in grams after washing.

7.1.5.3

Test Report. Report the amount of material passing the 75 micron sieve by washing to the nearest 0.1%, except if the result is 10% or more, report to the nearest 1.0%. Data sheets are given as Form 7.1.1 and 7.1.2.

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7.2

Particle Size Distribution of Aggregates

7.2.1

Dry sieving test

7.2.1.1

Introduction. This test is primarily used to determine the grading of materials proposed for use as aggregates or being used as aggregates. The results are used to determine compliance with the particle size distribution with applicable specification requirements and to provide necessary data for the control of the production of various aggregate products and mixtures containing aggregates.

7.2.1.2

Scope. This test covers the determination of the particle size distribution (PSD) or sieve analysis of fine and coarse aggregate by sieving. An accurate determination of the amount finer than the 75 micron sieve cannot be achieved by this method. Test method 7.1.5 should be used to determine the amount of material finer than the 75 micron sieve.

7.2.1.3

Equipment a) Balance, of appropriate capacity for the size of sample and capable of accuracy to 0.1% of the mass of the sample. b) Test sieves. A complete nest of sieves in accordance with the sizes required by the specification and which must comply with the relevant standards. Sieves with openings larger than 125mm shall have a permissible variation in average opening of plus or minus 2% and shall have a nominal wire diameter of 8.0mm or larger. A set of the sizes and apertures given in Table 7.2.1 will cover most applications of the method. c) Mechanical sieve shaker (Optional). d) Oven, of appropriate size capable of maintaining a uniform temperature of 110ºC plus or minus 5ºC. e) Trays and containers. Table 7.2.1

Particulars of sieves for sieve analysis

Square perforated plate, 450 mm or 300mm diameter

Wire cloth, 300 mm or 200 mm diameter

mm

mm (unless stated)

75.0 63.0 50.0 37.5 28.0 20.0 14.0 10.0 6.30 5.00

3.35 2.36 1.70 1.18 850 micron 600 micron 425 micron 300 micron 212 micron 150 micron 75 micron

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Table 7.2.2 Minimum mass of test portion required for sieve analysis Nominal size of material mm 63 50 40 28 20 14 10 6 5 3 less than 3

Minimum mass of test portion Kg. 50 35 15 5 2 1 0.5 0.2 0.2 0.2 0.1

7.2.1.4

Sampling. Sample the aggregate in accordance with test procedure described in Chapter 2.1. The test portion shall comply with the values given in Table 7.2.2. Reduction of the sample shall be made in accordance with 2.9.1.1.

7.2.1.5

Procedure a) If the test sample has not been subjected to testing using method 7.1 (material finer than the 75 micron test sieve by washing), dry it to constant mass at a temperature of 100ºC plus or minus 5ºC and determine the mass of it to the nearest 0.1% of the total original dry sample mass. b) Select the sieve sizes suitable to furnish the information required by the specification covering the material to be tested. Nest the sieves in order of decreasing opening size from top to bottom and place the sample, or portion of a sample if it is to be sieved in more than one increment, on the top sieve. Agitate the sieves by hand or by mechanical means for a sufficient period, established by trial or checked by measurement on the actual sample, to meet the criteria for adequacy of sieving described in the note below. Note.

Adequacy of sieving criteria : Sieve for a sufficient period and in such manner that, after completion, not more than 0.5% by mass of the total sample passes any sieve during 1 minute of continuous hand sieving performed as follows : Hold the individual sieve, provided with a snug-fitting pan and cover, in a slightly inclined position in one hand. Strike the side of the sieve sharply and with an upward motion against the heel of the other hand at the rate of about 150 times per minute, turn the sieve about one-sixth of a revolution at intervals of about 25 strokes. In determining sufficiency of sieving for sizes larger than the 4.75 mm sieve, limit the material on the sieve to a single layer of particles. If the size of the mounted testing sieves makes the described sieving motion impractical, use 200mm diameter sieves to verify the sufficiency of sieving.

c) Limit the quantity of material on a given sieve so that all particles have opportunity to reach the sieve opening a number of times during the sieving operation. For sieves with opening smaller than 4.75 mm the mass retained on any sieve at the completion of the sieving operation shall not exceed 6 kg/m2 , equivalent to 4 g/in2 of sieving surface. For sieves with opening 4.75 mm and larger, the mass in kg/m2 of sieving surface shall not exceed the product of (2.5) x (sieve opening in millimeters).

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Chapter 7 Tests For Aggregates And Bricks Note.

Standard Test Procedures

The 6 kg/m2 amounts to 194 g for the usual 200mm diameter sieve.

d) Determine the mass of each size increment by weighing to the nearest 0.1% of the total original dry sample mass. The total mass of the material after sieving should be checked closely with original mass of sample placed on the sieves. If the amounts differ dry more than 0.3%, based on the original dry sample mass, the results should not be used for acceptance purposes. e) If the sample had previously been tested by 7.1.5 add the amount finer than the 75 micron sieve determined by that method to the mass passing the 75 micron sieve by dry sieving of the same sample in this method. 7.2.1.6

Calculation. Calculate percentages passing, total percentages retained, or percentages in various size fractions to the nearest 0.1% on the basis of the total mass of the initial dry sample.

7.2.1.7

Report. The report shall include the following information: a) Total percentage of material passing each sieve. b) Total percentage of material retained on each sieve. c) Report percentages to the nearest whole number, except if the percentage passing the 75 micron sieve is less than 10%, it shall be reported to the nearest 0.1%. A data sheet is given as Form 7.2.1.

7.2.2

Fineness modulus of fine aggregate

7.2.2.1

Using the procedure for sieve analysis of fine aggregate described in 7.2.1 above, calculate the fineness modules by adding the total percentages of material in the sample that is coarser than each of the following sieves (cumulative percentages retained) and dividing the sum by 100.

7.2.2.2

Sieve size

Sieve size

150 micron 300 micron 600 micron 1.1mm 2.3mm

4.75mm 9.5 mm 19.0mm 37.5mm and larger, increasing the ratio of 2 to 1

Report. Report the fineness modulus to the nearest 0.01.

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7.3.

Shape Tests for Aggregates

7.3.1

Flakiness index

7.3.1.1

Introduction. Flaky or elongated materials, when used in the construction of a pavement, may cause the pavement to fail due to the preferred orientation that the aggregates take under repeated loading and vibration. It is important that the flakiness and elongation of the aggregate are contained to within permissible levels.

7.3.1.2

Scope. The scope of this test is to provide test methods for determining the flakiness index of coarse aggregate. An aggregate is classified as being flaky if it has a thickness (smallest dimension) of less than 0.6 of its mean sieve size. The flakiness index of an aggregate sample is found by separating the flaky particles and expressing their mass as a percentage of the mass of the sample tested. The test is not applicable to materials passing the 6.30 mm test sieve or retained on the 63.00 mm test sieve.

7.4.1.3

Equipment a) A sample divider, of size appropriate to the maximum particle size to be handled or alternatively a flat shovel and a clean, flat metal tray for the quartering. b) A ventilated oven, thermostatically controlled to maintain a temperature of 1050C plus or minus 50C. c) A balance of suitable capacity and accurate to 0.1% of the mass of the test portion. Balances of 0.5 kg, 5.0 kg, or 50 kg capacity may be required depending on the size of aggregate and size of sample. d) Test sieves. e) A mechanical sieve shaker (optional). f) Trays of adequate size, which can be heated in the oven without damage or change in mass. g) A metal thickness gauge, of the pattern shown in Figure 7.3.1, or similar, or special sieves having elongated apertures. The width and length of the apertures in the thickness gauge and in the sieves shall be within the tolerances given in Table 7.3.3. The gauge shall be made from 1.5 mm thickness sheet steel.

7.3.1.4

Preparation of test portion. Produce a test portion that complies with Table 7.3.2. Dry the test portion by heating at a temperature of 1050C plus or minus 50C to achieve a dry mass which is constant to within 0.1%. Allow to cool and weigh.

7.3.1.5

Procedure a) Carry out a sieve analysis using the test sieves in Table 7.3.1. Discard all aggregates retained on the 63.0 mm test sieve and all aggregate passing the 6.30 mm test sieve. Table 7.3.1

Particulars of test sieves

Nominal aperture size (square hole perforated plate 450 mm or 300 mm Diameter) 63.0 mm 50.0 mm 37.5 mm 28.0 mm 20.0 mm 14.0 mm 10.0 mm 6.3 mm

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Chapter 7 Tests For Aggregates And Bricks Table 7.3.2

Standard Test Procedures

Minimum mass of test portion

Nominal size of material

Minimum mass of test portion after rejection of oversize and undersize particles kg

mm 50 40 28 20 14 10 Table 7.3.3

35 15 5 2 1 0.5 Data for determination of flakiness index

Aggregate sizefraction

Aggregate sizefraction

mm 100% passing 63.0 50.0 37.5 28.0 20.0 14.0 10.0

mm

Width of slot in thickness gauge or special sieve mm

Minimum mass for subdivision kg

100% retained 50.0 37.5 28.0 20.0 14.0 10.0 6.30

33.9±0.3 26.3±0.3 19.7±0.3 14.4±0.15 10.2±0.15 7.2±0.1 4.9±0.1

50 35 15 5 2 1 0.5

b) Weigh each of the individual size-fraction retained on the sieves, other than the 63.0 mm and store them in separate trays with their size mark on the tray. c) From the sums of the masses of the fractions in the trays (M1), calculate the individual percentage retained on each of the various sieves. Discard any fraction whose mass is 5% or less of M1. Record the mass remaining M2. d) Gauge each fraction by using either of the procedures given in (i) or (ii) below. (i)

(ii)

Using the special sieves, select the special sieve appropriate to the sizefraction under test. Place the whole of the size-fraction into the sieve and shake the sieve until the majority of the particles have passed through the slots. Then gauge the particles retained by hand. Using the gauge, select the thickness gauge appropriate to the size-fraction under test and gauge each particle of that size-fraction separately by hand.

e) Combine and weigh all the particles passing each of the gauge M3. 7.3.1.6

Calculation and expression of results. The value of the flakiness index is calculated from the expression: Flakiness Index = 100 x M3 / M 2 number. Where,

Express the Flakiness Index to the nearest whole

M2 is the total mass of test portion M3 is the mass of the flaky portion MAY 2001

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7.3.1.7

Standard Test Procedures

Test Report. The test report shall affirm that the flakiness index test was performed according to the stated method and whether a sampling certificate was issued. If available the sampling certificate should be provided. The test report shall include the following additional information: a) Sample identification b) Flakiness index c) Sieve analysis obtained from this test. A data sheet is given as Form 7.3.1.

7.3.2

Elongation index

7.3.2.1

Scope. The scope of this test is to provide test methods for determining the elongation index of coarse aggregate. An aggregate is classified as being elongated if it has a length (greatest dimension) of more than 1.8 of its mean sieve size. The elongation index of an aggregate sample is found by separating the elongated particles and expressing their mass as a percentage of the mass of the sample tested. The test is not applicable to materials passing the 6.30 mm test sieve or retained on the 50.00 mm test sieve.

7.3.2.2

Equipment. The equipment used in the flakiness index are also used in the elongation index test except a metal length gauge instead of a thickness gauge shown in Figure 7.3.2. Table 7.3.4

Particulars of test sieves

Nominal aperture size (square hole perforated plate 450 mm or 300 mm Diameter) 50.0 mm 37.5 mm 28.0 mm 20.0 mm 14.0 mm 10.0 mm 6.3 mm Table 7.3.5

Minimum mass of test portion

Nominal size of material

mm 40 28 20 14 10

Minimum mass of test portion after rejection of oversize and undersize particles kg 15 5 2 1 0.5

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Table 7.3.6

Standard Test Procedures

Data for determination of elongation index

Aggregate sizefraction

Aggregate sizefraction

mm 100% passing

mm 100% retained

50.0 37.5 28.0 20.0 14.0 10.0

37.5 28.0 20.0 14.0 10.0 6.30

Width of slot in thickness gauge or special sieve mm

78.7±0.3 59.0±0.3 43.2±0.3 30.6±0.3 21.6±0.1 14.7±0.1

Minimum mass for subdivision kg

35 15 5 2 1 0.5

7.3.2.3

Preparation of test portion. Produce a test portion that complies with Table 7.3.4. Dry the test portion by heating at a temperature of 1050C plus or minus 50C to achieve a dry mass which is constant to within 0.1%. Allow to cool and weigh.

7.3.2.4

Procedure a) Carry out a sieve analysis using the test sieves in Table 7.3.5 or 7.3.6. Discard all aggregates retained on the 63.0 mm test sieve and all aggregate passing the 6.30 mm test sieve. b) Weigh each of the individual size-fraction retained on the sieves, other than the 50.0 mm and store them in separate trays with their size mark on the tray. c) From the sums of the masses of the fractions in the trays (M1), calculate the individual percentage retained on each of the various sieves. Discard any fraction whose mass is 5% or less of M1. Record the mass remaining M2. d) Gauge each fraction as follows: select the length gauge appropriate to the sizefraction under test and gauge each particle separately by hand. Elongated particles are those whose greatest dimension prevents them from passing through the gauge, and these are placed to one side. e) Combine and weigh all the particles passing each of the gauges M3.

7.3.2.5

Calculation and expression of results. The value of the elongation index is calculated from the expression: Elongation Index = 100 x M 3 / M 2 Express the Elongation Index to the nearest whole number. Where,

7.3.2.6

M3 is the mass of test portion being elongated M2 is the total mass of test portion

Test Report. The test report shall affirm that the elongation index test was performed according to the stated method and whether a sampling certificate was issued. If available the sampling certificate should be provided. The test report shall include the following additional information: a) Sample identification b) Elongation index c) Sieve analysis obtained from this test. A data sheet is given as Form 7.3.1.

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7.4

Fine Aggregate: Density and Absorption Tests

7.4.1

Introduction

7.4.1.1

Bulk specific gravity : Bulk specific gravity of the aggregate is a characteristic generally used for the calculation of the volume occupied by the aggregate in various mixtures containing aggregate including Portland cement concrete, bituminous concrete and other mixtures that are proportioned or analysed on an absolute volume basis. It is also used in the computation of voids in aggregate and the determination of moisture in aggregate by displacement in water. Bulk specific gravity determined on the saturated surface-dry basis is used if the aggregate is wet, that is, if its absorption has been satisfied. Bulk specific gravity determined on the oven-dry basis is used for computations when the aggregate is dry or assumed to be dry.

7.4.1.2

Apparent specific gravity : Apparent specific gravity pertains to the relative density of the solid material making up the constituent particles not including the pore space within the particles that is accessible to water. This value is not widely used in construction aggregate technology.

7.4.1.3

Absorption : Absorption values are used to calculate the change in the mass of an aggregate due to water absorbed in the pore spaces within the constituent particles, compared to the dry condition, when it is deemed that the aggregate has been in contact with water long enough to satisfy most of the absorption potential. The laboratory absorption is obtained after the aggregate has been submerged in water for approximately 24 hours.

7.4.2

Scope. This test provides methods for determining the bulk and apparent densities (after submersion in water for 24h) of fine aggregate, the bulk specific gravity on the basis of mass saturated surface-dry aggregate and water absorption of fine aggregate.

7.4.3

Equipment a) Balance, of capacity not less than 3 kg, accurate to 0.5g and of such type and size as to permit the basket containing the sample to be suspended from the beam and weight in water. b) Ventilated oven, thermostatically controlled to maintain the temperature at 105 ºC plus or minus 5 ºC. c) Pycnometer , capable of holding 0.5 kg to 1.0 kg of material up to 10mm nominal size and capable of being filled with water to a constant volume with an accuracy of plus or minus 0.5 ml. The volume of the pycnometer shall be least 50% greater than the volume required to accommodate the sample. d) Metal mould, in the form of a frustum of a cone 40 mm plus or minus 3mm diameter at the top, 90 mm plus or minus 3mm diameter at the bottom and 75 mm plus or minus 3 mm high. The metal shall be at least 900 micron thick. e) Container, of sufficient size to contain the sample covered in water and to permit vigorous agitation without any loss of material or water. f) 75 micron test sieve and a nesting sieve to protect the 75 micron sieve, e.g. a 1.18mm sieve. g) A metal tamper, of 340 g plus or minus 15 g and having a flat circular tamping face 25 mm plus or minus in 3mm diameter. h) A plain glass funnel (optional) i) A wide-mouthed glass vessel, Figure 7.4.1.

7.4.4

Preparation of test specimen a) A sample of about 1 kg for material having a nominal size 10mm to 5mm inclusive, or about 500 g if finer than 5mm, shall be used. A duplicate sample is also required. MAY 2001

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b) The sample shall be thoroughly washed to remove material passing the 75 micron sieve as follows : i)

Place the sample in the container and add enough water to it to cover it. Agitate vigorously the contents of the container and immediately pour the wash water over the test sieves, which have previously been wetted on both sides and arranged with the coarser test sieve to top. ii) The agitation shall be sufficiently vigorous to result in the complete separation from the coarse particles of all particles finer than the 75 micron sieve, and to bring the fine material into suspension in order that it will be removed by decantation of the wash water. Avoid, as far as possible, decantation of coarse material. Repeat the operation until the wash water appears to be clean. Return all material retained in the sieves to the washed sample. 7.4.5

Fine Aggregate Density and Absorption Test

7.4.5.1

Procedure using the pycnometer a) Transfer the washed aggregate to the tray and add further water to ensure that the sample is completely immersed. Soon after immersion, remove bubbles of entrapped air by gentle agitation with a rod. b) Keep the sample immersed for 24h plus or minus 2h, the water temperature being 20ºC plus or minus 5ºC for at least the last 20h of immersion. Then carefully drain the water from the sample through the 75 micron sieve, covered by the protective coarser sieve, any material retained being returned to the sample. c) Expose the aggregate to a gentle current of worm air to evaporate surface moisture and stir it at frequent intervals to ensure case of material finer than 5mm, it just attains a “free-running” condition. Refer Note 1 and to Figure 7.4.2 Weigh the saturated and surface-dried sample, Mass (A). If the apparent density only is required, the draining and drying operations described above may be omitted, although for material finer than 5mm some surface drying is desirable to facilitate handling. d) Place the aggregate in the pycnometer and fill the pycnometer with water. Screw the cone into place and eliminate any entrapped air by rotating the pycnometer on its side. Top up the pycnometer with water to remove any forth form the surface and so that the surface of the water in the hole is flat. Dry the pycnometer on the outside and weight it. Mass (B) e) Empty the contents of the pycnometer into a tray ensuring that all the aggregate is transferred. Refill the pycnometer with water to the same level as before, dry the outside of it and weight it. Mass (C). f) Carefully drain the water from the sample by decantation through the 75 micron test sieve and return any material retained to the sample. Place the sample in the tray, in the oven at a temperature of 105 C plus or minus 5 C for 24h plus or minus 0.5h, during which period it shall be stirred occasionally to facilitate drying. Cool to room temperature and weigh it, Mass (D). Note 1.

The “free-running” or “saturated surface-dry” condition of the fine aggregate is sometimes difficult to identify and in order to help in identification, two alternative methods are suggested for possible aids.

Method 1 After drying the sample with a stream of warm air allow it to cool to room temperature whilst thoroughly stirring it. Hold the mould with its larger diameter face downwards on a smooth non-absorbent level surface. Fill the mould loosely with part of the sample and lightly tamp 25 times through the hole at the top of the mould with the prescribed tamper. Do not refill the space left after tamping . Gently MAY 2001

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Standard Test Procedures

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Standard Test Procedures

lift the mould clear of the aggregate and compare the moulded shape with the figure in 7.4.2. If the shape resembles figure a) or b), there is still surface moisture present. Dry the sample further and repeat the test. If the shape resembles figure c), a condition close to the saturated surface-dry has been achieved. If the shape resembles figure d), the aggregate has dried beyond the saturated surface-dry and is approaching the oven-dry condition. In this case, reject the sample and repeat the test on a fresh sample. Method 2 As an alternative to method 1, a dry glass funnel may be used to help determine the “free-running” condition of aggregate finer than 5mm. With the funnel inverted over the sample tray pour some of the sample over the sloping sides by means of a small scoop. if still damp, particles of the aggregate will adhere to the sides of the funnel. Continue drying until subsequent pouring shows no sign of particles sticking to the glass. 7.4.5.2

Procedure using the wide-mouthed glass vessel. The procedure shall be the same as with the procedure using the pycnometer except that in filling the jar with water it shall be filled just to overflowing and the glass plate slid over it to exclude any air bubbles.

7.4.5.3

Calculations a) Particle density (i)

The particle density on an oven-dried basis in (Mg/m3) is calculated from the following expression. D/(A-(B-C))

(ii)

The particle density on a saturated and surface-dry condition in (Mg/m3) is calculated from the following expression. A/(A-(B-C))

(iii)

The Apparent particle density in (Mg/m3) is calculated from the following expression. D/(D-(B-C))

b) Water absorption The water absorption (as percentage of dry mass) is calculated from the following expression. 100 (A - D ) / D Where, A B C D

is the mass of saturated surface-dry sample in air, g. is the mass of pycnometers or wide-mouthed glass vessel containing sample filled with water, g. is the mass of pycnometers or wide-mouthed glass vessel filled with water only, g. is the mass of oven -dried sample in air, g.

A data sheet is given as Form 7.4.1. MAY 2001

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Standard Test Procedures

7.5

Coarse Aggregate: Density and Absorption Tests

7.5.1

Definitions of terminology

7.5.1.1

Absorption – the increase in the mass of aggregate due to water in the pores of the material, but not including water adhering to the outside surface of the particles, expressed as a percentage of the dry mass. The aggregate is considered dry when it has been maintained at 1050C plus or minus 50C for sufficient time to remove all.

7.5.1.2

Specific gravity – the ratio of the mass (or weight in air) of a unit volume of a material to the mass of the same volume of water at stated temperature to the weight in air of an equal volume of gas-free distilled water at the same temperature.

7.5.1.3

Apparent specific gravity – the ratio of the weight in air of a unit volume of the impermeable portion of aggregate at a stated temperature to the weight in air of an equal volume of gas-free distilled water at the same temperature.

7.5.1.4

Bulk specific gravity – the ratio of the weight in air of a unit volume of aggregate (including the temperature impermeable voids in the particles, but not including the voids between the particles) at a stated temperature to the weight in air of an equal volume of gas-free distilled water at the same temperature.

7.5.1.5

Bulk specific gravity (SSD) – the ratio of the mass in air of a unit volume of aggregate, including the mass of water within the voids filled to the extent achieved by submerging in water for approximately 24 h (but not including the voids between particles) at a stated temperature to the weight in air of an equal volume of gas-free distilled water at the same temperature.

7.5.2

Equipment a) Balance, of capacity not less than 3 kg, accurate to 0.5 g and of such type and size as to permit the basket containing the sample to be suspended from the beam and weighed in water. b) Ventilated oven, thermostatically controlled to maintain the temperature at 110 0C plus or minus 50C. c) A 4.75 mm test sieve and other sizes as needed. d) A sample container, such as a wire basket of 3.35 mm or finer mesh, or a bucket of approximately equal breadth and height, with a capacity of 4 L to 7 L for 37.5 mm nominal maximum size aggregate or smaller, and a larger container, as needed, for testing larger maximum size aggregate. e) Water tank, in which the sample and container are placed for complete immersion while being suspended below the balance. It must be capable of maintaining the level of water constant.

7.5.3

Preparation of test specimen

7.5.3.1

Receive a sample sampled in accordance with test method 2.4 and reduce to the required size as per method.

7.5.3.2

Reject all material passing the 4.75 mm test sieve of the test portion by dry sieving. Thoroughly wash the test portion to remove dust or other coatings from the surface. If the coarse aggregate contains a substantial quantity of material finer than the 4.75 mm sieve, use the 2.36 mm test sieve in place of the 4.75 mm test sieve or, alternatively, separate the material finer than the 4.75 mm sieve and test that portion in accordance with test method 7.4.

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Chapter 7 Tests For Aggregates And Bricks 7.5.3.3

Standard Test Procedures

The minimum mass of the test portion is given in Table 7.5.1 below. In many instances it may be desirable to test a coarse aggregate in several separate size fractions; and if the sample contains more than 15% retained on the 37.5 mm test sieve, test the material retained on the 37.5 mm sieve in one or more size fractions separately from the smaller size fractions. When an aggregate is tested in separate size fractions the minimum mass of test sample for each fraction shall be the differences between the masses prescribed for the maximum and minimum sizes of the fractions. Table 7.5.1 Nominal maximum size, mm

Minimum mass of test sample, kg

12.5 or less

2

19.0

3

25.0

4

37.5

5

50

8

63

12

75

18

7.5.4

Coarse aggregate density and absorption test

7.5.4.1

Procedure. A sample of not less than 2 kg of aggregate shall be tested. Aggregates which were artificially heated shall not normally be used. If such material is used, the fact shall be stated in the report. Two tests shall be performed. a) Place the prepared sample in the wire basket and immerse it in water at a temperature of 20 0C plus or minus 50C with a cover of at least 50 mm of water above the top of the basket. b) Immediately after immersion remove the entrapped air by lifting the wire basket about 25 mm above the base of the water tank and letting it drop 25 times at a rate of about once per second. The basket and aggregate shall remain in water for 24 h plus or minus 0.5 h. c) After this period weigh the basket and aggregate at a temperature of 200C plus or minus 50C. Record the mass to the nearest 1 g or 0.1% of the sample mass, whichever is greater, Mass B. d) Remove the test sample from the water and roll it in a large absorbent cloth until all visible film of water is removed. Wipe the larger particles individually. A warm stream of air may be used to assist in the drying operation. Take care to avoid the evaporation of water from the pores of the aggregate during the operation of surface-drying. Determine the mass of the sample in the saturated surface-dry condition, record the mass A. e) Dry the test sample to constant mass in the oven at 1050C plus or minus 50C, (24 h plus or minus 0.5 h will suffice), cool in air at room temperature until the aggregate has cooled to a temperature that is comfortable to handle. Weigh the dry aggregate and record as mass D. f) Weigh the wire basket in water at the specified temperature and record the weight as mass C.

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Chapter 7 Tests For Aggregates And Bricks 7.5.4.2

Standard Test Procedures

Calculations a) Bulk specific gravities The bulk specific gravity (saturated surface-dry) on a saturated and surface-dry condition in (Mg/m3) is calculated from the following expression. A / (A – (B – C)) (i)

The bulk specific gravity on the oven-dry basis (Mg/m3) is calculated from the following expression. D / (A – (B – C)) The apparent specific gravity (Mg/m3) is calculated from the following expressions. D / (D – (B – C)) Where, A is the mass of the saturated surface-dry sample in air, g. B is the apparent mass in water of the basket containing the sample of saturated aggregate, g. C is the apparent mass in water of the basket, g. D is the mass of the oven-dried aggregate in air, g.

(ii)

Average specific gravity values. When the sample has been tested in separate size fractions the average value for bulk specific gravity, bulk specific gravity (SSD), or apparent specific gravity can be computed as the weighted average of the values as computed above, using the following expression.

G =

1 P1 / 100 G 1 + P2 / 100 G 2 + ....... Pn / 100 G n

Where, G G1, G2 … Gn P1, P2 … Pn Note.

is the average specific gravity. All forms of specific gravity can be expressed in this manner. is the appropriate specific gravity values for each fraction depending on the type of specific gravity being averaged. is the mass percentages of each size fraction present in the original sample.

If the user wishes to express the specific gravity in terms of density, then the value for the specific gravity, which is dimensionless, is multiplied by the density of water at 40C, the temperature at which water is considered to have a density of 1000 kg/m3.

b) Absorption The water absorption (as percentage of dry mass) is calculated from the following expression. 100 (A – D) / D

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Chapter 7 Tests For Aggregates And Bricks Where,

(i)

A D

Standard Test Procedures

is the mass of the saturated surface-dry sample in air, g. is the oven-dry mass of the sample in air, g.

Average Absorption Value When the sample has been tested in separate size fractions the average absorption value can be computed as the weighted average of the values as computed above, using the following expression. A = P1A1 / 100 + P2A2 / 100 + ……. + PnAn / 100 Where, A A1, A2 … An P1, P2 … Pn

7.5.4.3

Acceptability of results. If the difference between any two test results falls outside the range of the values given in Table 7.5.2, the test results shall not be used for acceptability purposes and the tests shall be repeated. Table 7.5.2

7.5.4.4

is the average absorption percent. is the absorption percentages for each fraction. is the mass percentages of each size fraction present in the original sample.

Precision

Single operator

Acceptable range of two results

Bulk specific gravity (dry) Bulk specific gravity (SSD) Apparent specific gravity Absorption percent

0.025 0.020 0.020 0.025

Report a) Report specific gravity results to the nearest 0.01, and indicate the type of specific gravity, whether bulk, bulk (SSD), or apparent. b) Report the absorption result to the nearest 0.1%. A data sheet is given in Form 7.5.1.

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Standard Test Procedures

7.6

Aggregate Impact Value

7.6.1

Scope. The aggregate impact value gives a relative measure of the resistance of the aggregate to sudden shock or impact. The particular purpose which an aggregate is meant to serve requires the aggregate to have a particular strength which is usually stated in the specification. This test provides a method for measuring this strength.

7.6.2

Method outline. A test specimen, of chosen fractions, is compacted in a standardised manner, into an open steel cup. The specimen is then subjected to a number of standard impacts from a dropping weight. The impacts break the aggregate to a degree which is dependent on the aggregate’s impact resistance. This degree is assessed by a sieving test on the impacted specimen and is taken as the aggregate impact value.

7.6.3

Sampling. The sample used for this test shall be taken in accordance with Chapter 2.

7.6.4

Equipment

7.6.4.1

Impact testing machine. The machine shall be of the general form shown in Figure 7.6.1, have a total mass of between 45 kg and 60 kg and shall have the following parts: a) A circular metal base, with a mass of between 22 kg and 30 kg, with a plane lower surface of not less than 300 mm diameter and shall be supported on a level and plane concrete or stone block floor at least 450 mm thick. The machine shall be prevented from rocking during operation of the machine. b) A cylindrical steel cup, having an internal diameter of 102 mm plus or minus 0.5 mm and an internal depth of 50 mm plus or minus 0.25 mm. The walls shall be not less than 6 mm thick and the inner surfaces shall be case hardened. The cup shall be rigidly fastened at the centre of the base and be easily removed for emptying. c) A metal hammer, with a mass of between 13.5 kg and 14.0 kg, the lower end of which shall be cylindrical in shape, 100.0 mm plus or minus 0.5 mm diameter and 50 mm plus or minus 0.15 mm long, with a 1.5 mm chamfer at the lower edge, and case hardened. The hammer shall slide freely between vertical guides so arranged that the lower part of the hammer is above and concentric with the cup. d) Means for raising the hammer, and allowing it to fall freely between the vertical guides from a height of 380 mm plus or minus 5 mm on to the test sample in the cup, and means for adjusting the height of fall within 5 mm. e) Means for supporting the hammer whilst fastening or removing the cup.

7.6.4.2

Square-hole perforated plate test sieves, of sizes 14.0 mm and 10.0 mm and a wovenwire 2.36mm test sieve.

7.6.4.3

A cylindrical metal measure, of sufficient rigidity to retain its form under rough usage and with an internal diameter of 75 mm plus or minus 1 mm and an internal depth of 50 mm plus or minus 1 mm.

7.6.4.4

A tamping rod, made out of straight iron or steel bar of circular cross section, 16 mm plus or minus 1 mm diameter and 600 mm plus or minus 5 mm long, with both ends hemispherical.

7.6.4.5

A balance, of capacity not less than 500 g and accurate to 0.1 g.

7.6.4.6

A ventilated oven, thermostatically controlled at a temperature of 105 0C plus or minus 50C.

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7.6.4.7

A rubber mallet, a metal tray of known mass and large enough to contain 1 kg of aggregate and a brush with stiff bristles.

7.6.4.8

Additional equipment for testing aggregate in a soaked condition. a) Drying cloths or absorbent paper, for the surface drying of the aggregate. b) One or more wire-mesh baskets, with apertures greater than 6.5 mm. c) A stout watertight container in which the basket may be immersed.

7.6.5

Preparation of test portions and specimens

7.6.5.1

Test portions. Reduce laboratory samples to test portions of sufficient mass to produce 3 specimens of 14 mm to 10 mm size fraction. Table 7.6.1. Guide to minimum mass of test portions required to obtain a suitable mass of material to determine the aggregate impact value Grade of the aggregate

Minimum mass of test portion

All-in aggregate 40 mm max. size All-in aggregate 20 mm max. size Graded aggregate 40 to 5 mm Graded aggregate 20 to 5 mm Graded aggregate 14 to 5 mm 7.6.5.2

20 kg 15 kg 12 kg 8 kg 5 kg

Test specimen in a dry condition a) Sieve the entire dried test portion on the 14 mm and the 10 mm test sieve to remove the oversize and undersize fraction. Divide the resulting 14 mm to 10 mm size fractions to produce 3 test specimens each of sufficient mass to fill the measure when it is filled by the procedure in 7.6.5.2(c). b) Dry the test specimens by heating at a temperature of 1050C plus or minus 50C for a period of not more than 4 h. Cool to room temperature before testing. c) Fill the measure to overflowing with the aggregate using a scoop. Tamp the aggregate with 25 blows of the rounded end of the tamping rod, each blow being given by allowing the tamping rod to fall freely from a height of about 50 mm above the surface of the aggregate and the blows being distributed evenly over the surface. Remove the surplus aggregate by rolling the tamping rod across, and in contact with, the top of the container. Remove by hand any aggregate that impedes its progress and fill any obvious depressions with added aggregate. Record the net mass of aggregate in the measure and use the same mass for the second test specimen.

7.6.5.3

Test specimens in a soaked condition a) Prepare the test portion as in 7.6.5.1 except that the test portion is tested in the asreceived condition and not oven-dried. Place test specimen in a wire basket and immerse it in the water in the container with a cover at least 50 mm of water above the top of the basket. Remove entrapped air by lifting the basket 25 mm above the base of the container and allowing it to drop 25 times at a rate of approximately once per second. Keep the aggregate completely immersed in water at all times and for the next 24 h plus or minus 2 h and maintain the water temperature at 200C plus or minus 50C.

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b) After soaking, remove from the water and blot the free water from the surface using the absorbent cloths. Prepare for testing as described in 7.6.5.2 immediately after this operation. 7.6.6

Aggregate impact value

7.6.6.1

Procedure a) Test specimens in a dry condition (i)

(ii)

Fix the cup firmly in position on the base of the impact machine and place the whole of the specimen in it and then compact by 25 strokes of the tamping rod. Adjust the height of the hammer so that its lower face is 380 mm plus or minus 5 mm above the aggregate in the cup and then allow it to fall freely on to the aggregate. Subject the test specimen to 15 such blows each blow being delivered at an interval not less than 1 s. Remove the crushed aggregate by holding the cup over a clean tray and hammering on the outside with the rubber mallet until the crushed aggregate falls freely on to the tray. Transfer fine particle adhering to the inside of the cup and to the surface of the hammer to the tray by means of the stiff bristle brush. Weigh the tray and the aggregate and record the mass of the aggregate to the nearest 0.1 g (M1).

(iii)

(iv)

Sieve the whole of the specimen on the 2.36 mm test sieve until no further significant amount passes during a further period of 1 min. Weigh and record the mass of the fractions passing and retained on the sieve to the nearest 0.1 g (M2 and M3) respectively and if the total mass (M2 + M3) differs from the initial mass (M1) by more than 1 g, discard the result and test a further specimen. Repeat the procedure from (i) to (iii) above inclusive using a second specimen of the same mass as the first specimen.

b) Test specimens in a soaked condition (i)

(ii)

Follow the test procedure described in 7.6.6.1(a) except that the number of blows of the hammer to which the aggregate is subjected, is the number of blows which will yield between 5% and 20% of fines when this value is calculated using procedure in 7.6.6.2. Remove the crushed specimen from the cup and dry it in the oven at a temperature of 1050C plus or minus 50C either to constant mass or for a minimum period of 12 h. Allow to cool and weigh to the nearest 1 g and record this mass M1. Complete the procedure described in (ii) of 7.6.6.1(a) starting at the stage where the specimen is sieved on the 2.36mm test sieve.

7.6.6.2 Calculation and expression of result a) Calculate the aggregate impact value (AIV) expressed as a percentage to the first decimal place for each test specimen from the following expression. (AIV) = 100 x M2 / M1 Where, M1 M2

is the mass of the test specimen in grams. is the mass of the material passing the 2.36mm test sieve in grams.

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b) Aggregate in the soaked condition. (i)

Calculate the mass of fines, m, expressed as a percentage of the total mass for each test specimen from the following expression. M = 100 x M2 / M1 Where, M1 is the mass of the oven-dried test specimen in grams. M2 is the mass of the oven-dried material passing the 2.36mm test sieve in grams.

(ii)

Calculate the AIV expressed as a percentage to the first decimal place for each test specimen from the following expression. (AIV) = 15 m/ n Where, n is the number of hammer blows to which the specimen is subjected.

7.6.7.3

Results. Calculate the mean of the two values determined in (a) or (b) of 7.6.6.2 to the nearest whole number. Report the mean as the aggregate impact value, unless the individual results differ by more than 0.15 times the mean value. In this case repeat the test on two further specimens, calculate the median of the four results to the nearest whole number and report the median as the aggregate impact value. A data sheet is given in Form 7.6.1.

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7.7

Aggregate Crushing Value and 10% Fines Value

7.7.1

Aggregate Crushing Value (ACV)

7.7.1.1

Introduction. One of the requirements, for the suitability of aggregates for construction, is the ability of the aggregate to resist crushing. The Aggregate Crushing Value gives a relative measure of the resistance of the aggregate to crushing under a gradually applied compressive load.

7.7.1.2

Scope. The particular purpose which an aggregate is meant to serve requires the aggregate to have a particular strength. This strength is usually stated in the specification. This test provides a method for measuring this strength. This method is not suitable for testing aggregates with a crushing value higher than 30, and in this case the ten percent fines value is recommended.

7.7.1.3

Method outline. A test specimen, of chosen fractions, is compacted in a standardised manner, into a steel cylinder fitted with a freely moving plunger. The specimen is then subjected to a standard loading regime applied through the plunger. This action crushes the aggregate to a degree which is dependent on the aggregate’s crushing resistance. This degree is assessed by a sieving test on the crushed specimen and is taken as the Aggregate Crushing Value.

7.7.1.4

Sampling. The sample used for this test shall be taken in accordance with Chapter 2.

7.7.1.5

Equipment a) Steel cylinder, open-ended, of nominal 150mm internal diameter with plunger and base-plate of the general form and dimensions shown in Figure 7.7.1 and given in Table 7.7.1. The surface in contact with the aggregate shall be machined and case hardened, and shall be maintained in a smooth condition.

Table 7.7.1

Principal dimensions of cylinder and plunger apparatus

Component

Dimensions See Figure 7.7.1

Cylinder

Internal diameter, A Internal diameter, B Minimum wall thickness, C Diameter of piston, D Diameter of stem, E Overall length of piston plus stem, F Minimum depth of piston, G Diameter of hole, H Minimum thickness, I Length of each side of square, J

Plunger

Base-plate

Nominal 150 mm internal diameter of cylinder, mm 154±0.5 mm 125 to 140 mm 16.0 mm 152±0.5 mm >95 to = or
Nominal 75 mm internal diameter of cylinder mm 78±0.5 mm 70.0 to 85.0 mm 8.0 mm 76.0±0.5 mm >45.0 to = or
100 to 115 mm Not less than 25.0 20.0±0.1 mm 10 mm

60.0 to 80.0 mm Not less than 19.0 10.0±0.1 mm 10 mm

200 to 230 mm

110 to 115 mm

b) A cylindrical metal measure, of sufficient rigidity to retain its form under rough usage and with an internal diameter of 115 mm plus or minus 1 mm and an internal depth of 180 mm plus or minus 1 mm. c) A tamping rod, made out of straight iron or steel bar of circular cross section. 16 mm plus or minus 1 mm diameter and 600 mm plus or minus 5 mm long, with both ends hemispherical. d) A balance, of capacity not less than 3 kg and accurate to 1 g. MAY 2001

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Figure 7.7.1

Standard Test Procedures

Outline form of cylinder and plunger apparatus for the aggregate crushing value and ten percent fines test

e) A ventilated oven, thermostatically controlled at a temperature of 105 0C plus or minus 50C. f) A rubber mallet, a metal tray of known mass and large enough to contain 3 kg of aggregate and a brush with stiff bristles. g) Square-hole perforated plate test sieves, of sizes 14.0 mm and 10.0 mm and an ovenware 2.36 mm test sieve. h) A compression testing machine, capable of applying any force up to 400 kN at a uniform rate of loading so that the force is reached in 10 min. 7.7.1.6

Preparation of test portions and specimens a) Test portions. Reduce laboratory samples to test portions of sufficient mass to produce 3 specimens of 14 mm to 10mm size fractions. b) Sieve the entire dried test portion on the 14mm and the 10mm test sieve to remove the oversize and undersize fraction. Divide the resulting 14mm to 10 mm size

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fractions to produce 3 test specimens each of sufficient mass that the depth of the material in the cylinder is approximately 100 mm after tamping. c) Dry the test specimens by heating at a temperature of 1050C plus or minus 50C for a period of not more than 4 h. Cool to room temperature and record the mass of the material comprising the test specimen. Table 7.7.2

Guide to minimum mass of test portions required to obtain a suitable mass of material to determine the Aggregate Crushing Value.

Grade of the aggregate All-in aggregate 40 mm max. size All-in aggregate 20 mm max. size Graded aggregate 40 to 5 mm Graded aggregate 20 to 5 mm Graded aggregate 14 to 5 mm 7.7.1.7

Minimum mass of test portion 60 kg 45 kg 40 kg 25 kg 15 kg

Procedure a) Place the cylinder of the test apparatus in position on the base-plate and add the test specimen in three layers of approximately equal depth, each layer being compacted to 25 strokes from the tamping rod distributed evenly over the surface of the layer and dropping from a height approximately 50 mm above the surface of the aggregate. Carefully level the surface of the aggregate and insert the plunger so that it rests horizontally on this surface. Ensure that the plunger is free to move. b) Place the apparatus, with the test specimen prepared as described in 7.7.1.6(c) and plunger in position, between the platens of the testing machine and load it as uniform a rate as possible so that the required force of 400 kN is reached in 10 min plus or minus 30 s. c) Release the load and remove the crushed aggregate by holding the cylinder over a clean tray of known mass and hammering on the outside with the rubber mallet until the crushed aggregate falls freely on to the tray. Transfer fine particle adhering to the inside of the cylinder and to the surface of the hammer to the tray by means of the stiff bristle brush. Weight the tray and the aggregate and record the mass of the aggregate to the nearest 1g (M1). d) Sieve the whole of the specimen on the 2.36mm test sieve until no further significant amount passes during a further period of 1 min. Weight and record the mass of the fractions passing and retained on the sieve to the nearest 1g (M2 and M3) respectively and if the total mass (M2 + M3) differs from the initial mass (M1) by more than 10g, discard the result and test a further specimen. e) Repeat the procedure from (a) to (b) above inclusive using a second specimen of the same mass as the first specimen.

7.7.1.8

Calculation and expression of result. Calculate the Aggregate Crushing Value (ACV) expressed as a percentage to the first decimal place, of the mass of fines formed to the total mass of the test specimen from the following expression. (ACV) = 100 x M2 / M1 Where, M1 is the mass of the test specimen in grammes. M2 is the mass of the material passing the 2.36mm test sieve in grammes. MAY 2001

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7.7.1.9

Standard Test Procedures

Results. Calculate the mean of the two values determined to the nearest whole number. Report the mean as the Aggregate Crushing Value, unless the individual results differ by more than 0.07 times the mean value. In this case repeat the test on two further specimens, calculate the median of the four results to the nearest whole number and report the median as the Aggregate Crushing Value. A data sheet is given as Form 7.7.1.

7.7.2

10% Fines Value Test

7.7.2.1

Scope. The particular purpose which an aggregate is meant to serve requires the aggregate to have a particular strength. This strength is usually stated in the specification. This test provides a method for measuring this strength. This method is suitable for testing both strong and weak aggregate passing a 14.0 mm test sieve and retained on a 10.0 mm test sieve.

7.7.2.2

Method outline. A test specimen, of chosen fractions, is compacted in a standardised manner, into a steel cylinder fitted with a freely moving plunger. The specimen is then subjected to a standard loading regime applied through the plunger. The action crushes the aggregate to a degree which is dependent on the aggregate’s crushing resistance. This degree is assessed by a sieving test on the crushed specimen. The procedure is repeated with various loads to determine the maximum force which generates a given sieve analysis. This force is taken as the ten percent fines value (TFV).

7.7.2.3

Sampling. The sample used for this test shall be taken in accordance with Chapter 2.

7.7.2.4

Equipment. The equipment required for this test is identical to the equipment required for the ACV test as described in 7.7.1.5. a) b) c) d)

7.7.2.5

Additional equipment for testing aggregate in a soaked condition. Drying cloths or absorbent paper, for the surface drying of the aggregate. One or more wire-mesh baskets, with apertures greater than 6.5 mm. A stout watertight container in which the basket may be immersed.

Preparation of test portions and specimens a) Test portions Reduce laboratory samples to test portions of sufficient mass to produce 3 specimens of 14 mm to 10mm size fraction. Use Table 7.7.1 for a guide to the minimum mass of test portion required to obtain a mass of material to determine the aggregate 10% fines value. b) Test specimen in a dry condition (i)

(ii)

Sieve the entire dried test portion on the 14 mm and the 10 mm test sieve to remove the oversize and undersize fraction. Divide the resulting 14 mm to 10 mm size fractions to produce 3 test specimens each of sufficient mass such that the depth of the material in the cylinder is approximately 100 mm after tamping. Dry the test specimens by heating at a temperature of 1050C plus or minus 50C for a period of not more than 4 h. Cool to room temperature before testing. Record the mass of the material comprising the test specimen. MAY 2001

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c) Test specimens in a soaked condition (i)

(ii)

7.7.2.6

Prepare the test portion as in 7.7.1.6(b) except that the test portion is tested in the as-received condition and not oven-dried. Place test specimen in a wire basket and immerse it in the water in the container with a cover at least 50 mm of water above the top of the basket. Remove entrapped air by lifting the basket 25 mm above the base of the container and allowing it to drop 25 times at a rate of approximately once per second. Keep the aggregate completely immersed in water at all times and for the next 24 h plus or minus 2 h and maintain the water temperature at 200C plus or minus 50C. After soaking, remove from the water and blot the free water from the surface using the absorbent cloths. Carry out the test procedure immediately after this operation.

Procedure: Aggregates in dry condition a) Place the cylinder of the test apparatus in position on the base-plate and add the test specimen in three layers of approximately equal depth, each layer being compacted to 25 strokes from the tamping rod distributed evenly over the surface of the layer and dropping from a height approximately 50 mm above the surface of the aggregate. Carefully level the surface of the aggregate and insert the plunger so that it rests horizontally on this surface. Ensure that the plunger is free to move. b) Place the apparatus, with the test specimen and plunger in position, between the platens of the testing machine and load it as uniform a rate as possible so as to cause a total penetration of the plunger in 10 min plus or minus 30 s of approximately: (i) 15 mm for rounded or partially rounded aggregates (uncrushed gravels). (ii) 20 mm for normal crushed aggregate. (iii) 24 mm for vesicular (honeycombed) aggregates. c) Record the force (f) applied to produce the required penetration. Release the load and remove the crushed aggregate by holding the cylinder over a clean tray of known mass and hammering on the outside with the rubber mallet until the crushed aggregate falls freely on to the tray. Transfer fine particle adhering to the inside of the cylinder and to the surface of the hammer to the tray by means of the stiff bristle brush. Weigh the tray and the aggregate and record the mass of the aggregate used to the nearest 1 g (M1). d) Sieve the whole of the specimen on the 2.36 mm test sieve until no further significant amount passes during a further period of 1 min. Weigh and record the mass of the fractions passing and retained on the sieve to the nearest 1 g (M2 and M3) respectively and if the total mass (M2 + M3) differs from the initial mass (M1) by more than 10 g, discard the result and test a further specimen. If the percentage of the material (m) passing the sieve, calculated from the expression: M = 100 x M2 / M1 does not fall within the range 7.5% and 12.5%, test a further specimen, using an adjusted maximum test loading to bring the percentage of fines within the range and record the value of (m) obtained. e) Repeat the complete test procedure with the same mass of aggregate at the same force that gives percentage fines value within the range 7.5% and 12.5%.

7.7.2.7

Procedure; aggregates in a soaked condition a) Follow the procedure described in 7.7.2.6(a) except that after the crushed specimen has been removed from the cylinder, dry it in the oven at a temperature MAY 2001

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of 1050C plus or minus 50C either to constant weight or for a minimum of 12 h. Allow the dried material to cool and weigh to the nearest 1 g (M1). Complete the procedure 7.7.2.6(d) and 7.7.2.6(e). 7.7.2.8

Calculation and expression of result a) Calculate the force F (in kN), to the nearest whole number, required to produce 10% fines for each test specimen, with the percentage of material passing in the range of 7.5% to 12.5%, from the following expression: F = 14 f / (m + 4) Where, f is the maximum force in kN. m is the percentage of material passing the 2.36 mm test sieve at the maximum force. b) Calculate the mean of the two results to the nearest 10 kN or more or to the nearest 5 kN for forces of less than 100 kN. Report the mean as the aggregate 10% fines value, unless the individual results differ by more than 10 kN or by more than 0.1 times the mean value. In this case repeat the test on two further specimens, calculate the median of the four results to the nearest whole number and report the median as the aggregate 10% fines value. A data sheet is given as Form 7.7.1.

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7.8

Tests for Bricks

7.8.1

Introduction. Since bricks are made from variable naturally occurring materials, care should be exercised in placing too much importance on the test results obtained on a single sample. For test results to be meaningful and useful in the evaluation of material properties the tests have to be carried out according to the prescribed method and perhaps even more importantly the samples have to represent the materials being tested.

7.8.2

Determination of dimensions

7.8.2.1

Size. The standard dimensions of common bricks shall be:

7.8.2.2

Length

Width

Depth / Height

240 mm

115 mm

70 mm

Size of voids a) Solid bricks shall not have holes, cavities or depressions. b) Cellular bricks shall not have holes, but may have frogs or cavities not exceeding 20% of the gross volume of the brick. c) Perforated bricks shall have holes not exceeding 25% of the gross volume of the brick. The area of any one hole shall not exceed 10% of the gross area of the brick. d) Frogged bricks shall have depressions in one bed. Frog size should not exceed 130 mm x 50 mm x 10 mm.

7.8.2.3. Variation. Small variation in the dimension shall be permissible to the following extent only : Table 7.8.1 Specified Dimension

7.8.2.4

Maximum Permissible Variation

Over 50 mm and upto 75 mm

±1.5 mm

Over 75 mm and upto 100 mm

±3.0 mm

Over 100 mm and upto 150 mm

±5.0 mm

Over 150 mm and upto 250 mm

±6.0 mm

Dimensional deviations. The overall measurements of 24 bricks shall not fall outside the limits given in Table 7.8.2. In addition, the size of any individual brick shall not exceed the size given in 7.8.2. Table 7.8.2 Sizes

7.8.2.5

Overall measurement of 24 bricks Maximum

Minimum

240 mm

5880 mm

5680 mm

115 mm

2910 mm

2810 mm

70 mm

1710 mm

1650 mm

Procedure for measuring dimensions a) Take 24 bricks. Remove any blisters, small projections or loose particles of clay adhering to the brick. Place the bricks in contact with each other in a straight line MAY 2001

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upon a level surface, using the appropriate arrangement for each work size shown in Figure 7.8.1. b) Measure the overall dimension (Length, width or height) to the nearest millimeter, using an in extensible measure long enough to measure the whole row at one time, results recorded in Form 7.8.1. Note.

Alternatively, the sample may be divided in half to form 2 rows of 12 bricks. Measurement of each row is made separately and the results are summed up.

7.8.3

Relative density and absorption

7.8.3.1

Introduction. The relative density of bricks may be measured using the saturated surface-dry (SSD) method used for the determination of density of cores and concrete specimens.

7.8.3.2

Density. The density of bricks is defined as the average density of 10 bricks sampled according to this test method and tested on the SSD basis.

7.8.3.3

Water absorption. The test method for the determination of water absorption in this standard is the 5 h boiling test.

7.8.3.4

Equipment. The equipment required for this test is listed below: a) Ventilated drying oven with automatic control capable of maintaining a constant temperature of 110 – 1150C. b) Water tank, provided with a grid to ensure free circulation of water between masonry units and the bottom of the tank. c) Balance capable of weighing to an accuracy of 0.1% of the mass of the specimen.

7.8.3.5

Preparation of specimens a) Use 10 bricks sampled in accordance with this test procedure. b) Dry the specimen to constant mass in the oven at a temperature of between 110 and 1150C. When cool, weigh each specimen to an accuracy of 0.1% of its mass.

7.8.3.6

Test procedure a) Place the 10 specimens in a single layer in a tank of water immediately after weighing, so that the water can circulate freely on all sides of them. Leave a space of about 10 mm between bricks and the sides of the tank. b) Heat the water to boiling point in approximately 1 h. c) Boil for 5 h continuously, and then allow to cool to room temperature by natural loss of heat for not less than 16 h or more than 19 h. d) Remove the specimens, wipe off the surface water with a damp cloth and weigh. When wiping perforated bricks, shake them to expel water that might otherwise be left in the perforations. e) Complete weighing any one specimen within 2 min after its removal from the water.

7.8.3.7

Calculation of water absorption. Calculate the water absorbed by each specimen. A, expressed as a percentage of the dry mass, using the following expression. A = 100 x (wet mass – dry mass) / dry mass Calculate the average of the water absorption’s of the 10 specimens to the nearest 0.1%. A data sheet is given as Form 7.8.2. MAY 2001

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7.8.3.8

Standard Test Procedures

Maximum permissible water absorption. The water absorption shall in no case be greater than the water absorption for the appropriate class of brick given in Table 7.8.3 below. Table 7.8.3 Classification of bricks by compressive strength and water absorption Grade

Compressive Strength Average for 12 halved bricks (N/mm2)

Water absorption for 10 bricks (%)

A

28

Minimum for individual halved bricks (N/mm2) 21.1

B

17.5

14

12

C

10.5

8.4

16

10

7.8.4

Compressive strength determination

7.8.4.1

Introduction. The compressive strength of bricks shall in no case be less than the compressive strength for the appropriate class of brick given in Table 7.8.3. When bricks are to be broken for use as road making, aggregate tests such as the Los Angles abrasion, aggregate crushing strength and aggregate impact value may give a more satisfactory indication of their suitability for use.

7.8.4.2

Equipment. The equipment required for the determination of compressive strength of brick is listed below: 1. Testing machine, compatible with the testing machine required for testing concrete specimens and capable of applying the rate of loading specified in the test procedure. Testing machine requirements: It shall be equipped with two permanent ferrous bearing platens which shall be at least as large as any plywood packing or, where such packing is not being used, the bedding faces of the specimens being tested. The upper machine platen shall be able to align freely with the specimens as contact is made but the platens shall be restrained by friction or other means from tilting with respect to each other during loading. The lower compression platen shall be plain, non-tilting bearing block. The testing face of the platen shall be hardened and shall have: a) a flatness tolerance of plus or minus 0.05 mm b) a parallelism tolerance for one face of each platen with respect to the other of 0.10 mm. c) a surface texture not greater than 3.2 micron

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7.8.4.3

Preparation of specimen. Twelve bricks taken at random from sample shall be halved and one half from each whole brick used for determining the compressive strength. The overall dimension of each bedding face shall be measured to the nearest of 1.3 mm and the area of the face having smaller area shall be taken as the area of the bricks for testing the compressive strength.

7.8.4.4

Test procedure a) Bricks with frogs 1) Immerse the bricks in water at room temperature for 24 hours. They shall then be removed and allow to dry at room temperature for about 5 minutes. 2) Then fill the frogs with cement-sand mortar with a ratio of 1:11/2. Sand should be clean and well graded and passing through 3.35 mm sieve. Trowel the mortar off flush with surface of the bricks. 3) After filling the frogs, store the bricks under the damp sacks for 24 hours and then immerse in water for 6 days before bricks are considered ready for testing. After seven days of filling the frogs, take out the specimens and wipe off the moisture with damp cloth. 4) Then place the specimen with flat surface horizontally and the mortar filled face facing upwards between two plywood sheets of 3-ply, normally 3 to 4 mm thick and carefully centered between the plates of the compression testing machine. 5) Then apply the load axially at a uniform rate of 14 N/mm 2 per minute, until failure. The failure shall be deemed to have occurred when no further increase in the load is registered with unchanged rate of moving head travel. 6) Calculation of compressive strength: Obtain the strength of each specimen by dividing the maximum load obtained during loading by the appropriate area of the bed face. Record the strength in N/mm2 to the nearest 0.1 N/mm2. Calculate the average of the 12 compressive strengths and report it to the nearest 0.1 N/mm2. b) Solid bricks / bricks with a frog intended to be laid downwards / perforated bricks / cellular bricks Immerse the brick in water for 6 days or saturate the brick by boiling as described in water absorption test. Then follow the 7.8.4.4(a)(4) and 7.8.4.4(a)(5). c) Solid bricks with cavities Fill the cavities with capping compound or mortar mix and immerse in water for 6 days and then follow 7.8.4.4(a)(4) and 7.8.4.4(a)(5). d) Brick with holes No capping compound is used and holes remain empty. Immerse the brick in water for 6 days, take out and wipe off the moisture and then follow 7.8.4.4(a)(4) and 7.8.4.4(a)(5).

7.8.4.5

Calculation of compressive strengths Strength = Maximum load in Newton / net area of brick in mm2. For bricks with holes, net area of brick = Gross area of brick – area of holes. Gross area = Length of brick x width of brick. MAY 2001

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Chapter 7 Tests For Aggregates And Bricks

Area of hole = π Note.

Standard Test Procedures

d2 where d is the diameter of the hole 4

When bricks are to be used as crushed aggregate, for in a blend as unfound material, the necessity to determine the compressive strength accurately as it is when the bricks are to be used in load-bearing walls, is not so critical (see 7.8.4.1)

7.8.4.6 Report. Report the compressive strength in a data sheet to the nearest 0.1 N/mm2. Data sheets are given as Forms 7.8.3 and 7.8.4.

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CHAPTER 8 TESTS ON CEMENT

8.1

Fineness of Cement

8.1.1

Introduction. This simple test is not intended to indicate the true fineness of a cement as may be determined by apparatus for measuring the specific surface, but it is intended to give an indication of any hydration in the cement which has led to the formation of small pieces of hardened material. If a sample of cement contains any hardened lump of cement, it is clearly unsuitable for structural work and should be rejected without further test.

8.1.2

Apparatus a) 75 micron sieve b) Balance (accuracy 0.01g)

8.1.3

Preparation of sample. The sample should be taken from at least 10 different bags and divided by means of quartering or riffling. About 100 grams of cement is required. Care should be taken in handling the sample to ensure that no crushing of particles takes place.

8.1.4

Test procedure a) The sample should be weighed to the nearest 0.1 grams, Weight A and then sieved a little at a time on a 75 micron sieve. Care should be taken to prevent loss of cement dust during loading and the sieve should be nested between a lid and a receiver whilst sieving. Sieving of any portion should not continue for longer than 4 minutes and not more than 25 grams of cement should be placed on the sieve at any time. A bristle brush should be used to clean the mesh as required. b) The material retained on the sieve from each portion should be collected in suitable dishes. There should be no cement dust adhering to the retained material. If necessary, the retained material should be re-sieved to remove fines. The total weight of material retained, Weight B, is determined. c) To check that no significant weight of dust has been lost, the weight of the material in the receiver, Weight C, should be determined.

8.1.5

Calculation Weight A' = Weight B + Weight C Loss of material during test = Weight A - Weight A' The loss in weight should not exceed 0.5% of the original weight. Percentage retained on the 75 micron sieve =

8.1.6

Weight B x 100% WeightA

Reporting of results. The percentage retained on the 75 micron sieve should be reported to the nearest 1 percent.

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8.2

Setting Time of Cement

8.2.1

Introduction The setting times of cement give an indication of how long the cement will remain workable when used in a concrete mix. If the cement has deteriorated or was originally defective, it may take an excessive time to set.

8.2.2

Apparatus The apparatus used for the test is the standard Vicat apparatus as shown in Figure 8.2.1. The apparatus is essentially a simple penetrometer, the sample of cement paste being placed in the mould below the sliding weight. The weight may be varied by placing calibrated weights within the stem and three different penetration devices may be fitted to the underside of the weight. The total sliding weight including the penetration attachments should be 300 ± lg.

8.2.3

Sample preparation a) The sample must be mixed with the correct amount of water to give a standard consistency. The standard consistence is determined by means of the Vicat apparatus fitted with the plunger, a 10mm diameter blunt-ended, metal cylinder weighing 9.0± 0.5. g. b) The freshly mixed cement paste is placed in the mould and levelled off with a trowel. The plunger is brought into contact with the surface of the paste and then released. c) The paste is at the correct consistence when the plunger penetrates to a points 5± 1 mm. from the bottom of the mould. The depth of penetration is shown on the scale. Fresh samples of paste with varying water contents should be tested until the desired consistence is achieved. d) Normally, a weight of water between 26 and 33 percent of the weight of the dry cement is required to obtain the standard consistence. Note.

8.2.4

Note that the procedure of determining consistence should not take longer than about 5 minutes.

Test procedure a) A fresh sample of cement paste of standard consistence should be placed in the mould and levelled off using a trowel. b) The initial set needle should be fitted to the apparatus, this needle is a bluntended cylinder of diameter 1.13 mm. and weighing 9.0 ± 0.5g. with the needle in position the sliding portion of the apparatus should weight 300 grams. The weight should be checked prior to the start of the test. c) To determine the initial setting time the needle is brought into contact with the surface of the cement paste and released. Initially the needle will penetrate completely through the paste to the base of the mould, but the test is repeated at regular intervals at different points on the surface until the needle only penetrates to within 5 ± 1 mm. of the base of the mould. The time elapsed from initially mixing the cement with water until the desired penetration is reached is the initial setting time.

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d) To determine the final setting time the final set needle is fitted to the apparatus. The final set needle is a cylindrical blunt-ended needle which is fitted with a metal collar which is hollowed out to leave a 5 mm. diameter cutting edge 0.5 mm. behind the tip of the needle. The weight should be 9.0 ± 0.5 g. e) The needle is brought gently into contact with the surface of the paste and released. This operation is repeated at intervals until the tip of the needle marks the paste but the cutting edge does not come into contact with the paste. The time elapsed from initial mixing of the cement and water until this stage is reached is the final setting time. Note 1.

For ordinary Portland cement the initial time of setting is not less than 45 minutes and the final time of setting is not more than 375 minutes by Vicat test.

Note 2. It should be noted that the setting times will be reduced as the temperature of the paste increases, and the temperature of the test should be maintained at 30 ± 20C to give consistent results. To prevent premature hardening of the surface of the paste, the humidity should exceed 90%; this may be achieved by covering the apparatus with a damp, but not dripping, towel between determinations. 8.2.5

Reporting of results The initial setting time should be reported to the nearest 5 minutes and the final setting time should be reported to the nearest 30 minutes. The temperature of the test should be stated.

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8.3

Compressive Strength of Cement

8.3.1

General Requirements

8.3.1.1

Scope: The strength of cement is determined by compressive strength tests, on 100mm concrete cubes, or 70.7mm mortar cubes, made with specified coarse and fine aggregates, in the case of the 100mm concrete cubes and specified sand in the case of the 70.7 mortar cubes, mixed by a machine and compacted manually with a compacting bar. Note.

The water/cement ration is 0.60 (C1, Table 8.3.1) for all cements except super sulphated and high alumina, for which values of 0.55 (C2 Table 8.3.1) and 0.45 (C3 Table 8.3.1) respectively are used.

Table 8.3.1 Mixes for concrete cubes (in grams) Mix type Material Proportion Mass for by mass 6 cubes Cement 1.0 2200±5 C1 Sand 2.5 5500 Coarse 3.5 7700±10 agg. 0.60 1320±5 Water Cement 1.0 2200±5 C2 Sand 2.5 5500 Coarse 3.5 7700±10 agg. 0.55 1210±5 Water Cement 1.0 2940±5 C3 Sand 1.875 5500 Coarse 2.625 7700±10 agg. 0.45 1320±-5 Water 8.3.1.2

Mass for 9 cubes 3200±5 8000 11200±10 1920±5

Mass for 12 cubes 4200±5 10500 14700±10 2520±5

3200±5 8000 11200±10 1760±5

4200±5 10500 14700±10 2310±5

4270±5 8000 11200±10 1920±5

5600±5 10500 14700±10 2520±5

Apparatus

8.3.1.2.1 Moulds a) Construction and assembly. The sides of the mould shall be made from ferrous metal. The mould shall include a removable ferrous metal base plate. All parts shall be robust enough to prevent distortion. Before assembly for use, the joints between the sides of the mould and between the sides and the base plate shall be thinly coated with oil or grease to prevent loss of water. The whole assembly when completed must be rigidly held together in such a manner as to prevent leakage from the mould. The internal faces of the mould shall be thinly coated with release agent to prevent adhesion of the concrete. Tolerances: The dimensional deviations shall be as follows: i)

Dimensions: The internal depth of the mould when assembled and the distance between the two pairs of opposite internal faces, shall be 100 mm plus or minus 0.15 mm for the 100mm moulds and 70.7 mm plus or minus 0.1mm for the 70.7 mm moulds

ii)

Flatness: The flatness tolerance for each internal side face when assembled shall be 0.03mm wide for the both the 70.7mm and the 100mm moulds. The flatness tolerance for the joint faces, for the top and bottom

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Standard Test Procedures surfaces of the assembled mould sides and the top surface of the base plate shall be 0.06mm wide.

iii)

Squareness: When assembled, the squareness tolerance for each internal side face with respect to the adjacent internal side face and top of the base plate shall be 0.5 mm wide for the both the 70.7 mm and the 100 mm moulds.

iv)

Parallelism: When assembled, the parallelism tolerance for the top surface of the mould with respect to the top surface of the base plate shall be 1.0mm wide both for the 70.7mm and the 100mm moulds.

v)

Surface texture: The surface texture of each internal side face shall not exceed 3.2 micron when determined in accordance with BS 1134 both for the 70.7 mm and the 100 mm moulds.

8.3.1.2.2 Scoop, approximately 100mm wide. 8.3.1.2.3 Square mouthed shovel, size 2 BS 3388. 8.3.1.2.4 Plasterer’s steel float. 8.3.1.2.5 Compacting bar weighing 1.8 plus or minus 0.1 kg, at least 380mm long and having a ramming face of 25 plus or minus 0.5mm square. 8.3.1.2.6 Mixer. The concrete mixer shall be of suitable capacity to mix a concrete batch in one operation. It shall comprise a rotating mixing pan with contra-rotating mixing paddle and a scraper blade as shown in Figure 8.3.1 and Figure 8.3.2. The mixing pan shall rotate at 18 plus or minus 1r/min. The mixing paddle shall rotate at 90 plus or minus 5 r/min. The mixer shall preferably be fitted with an automatic timing device otherwise a stopwatch should be provided. 8.3.1.2.7 Tank. The tank shall contain clean tap water which shall be replace at least every 7 days with water at the specified temperature. 8.3.1.2.8 Compression testing machine. Over the scale range used, the machine shall be capable of applying the load at a rate of about 0.25 N/mm2 per second for the 100mm concrete moulds and at a rate of about 0.60Mpa for the 70.7mm mortar moulds and shall comply with grade 1 of BS 1610. 8.3.1.3

Temperature and humidity conditions. The temperature throughout the entire test procedure should be controlled at 200C with permitted variations as shown in Table 8.3.2. The minimum relative humidity shall be as given in Table 8.3.2. Table 8.3.2 Temperature and humidity conditions. Situation

Permitted temperature Variation, 0C

Mixing room Moist curing chamber Water curing tank Water curing tank

±2 ±1 ±1 ±2

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Minimum Relative Humidity % 50 90 50

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Figure 8.3.3 : Typical Vibration Machine for compacting Mortar Cubes

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8.3.1.4 Preparation of samples. The specimens shall be prepared as follows: 8.3.1.4.1 Number of cubes. Make batches of six, nine, or twelve cubes for testing at the specified ages. 8.3.1.4.2 Aggregates. The coarse aggregate and sand shall comply. 8.3.1.4.2.1 Standard coarse aggregate for concrete cubes (100mm 70.7mm moulds). a)

Scope. The coarse aggregate shall consist of clean, substantially free from dust and dry crushed granite, in one fraction, 10mm to 5mm nominal size, 30Kg of aggregate is required for sampling purposes and it shall be reduced, using a sample divider, to six sub-samples of about 500g each.

b)

Grading. The coarse aggregate shall comply with the grading requirements of the table below:

Test sieve 10.00mm 5.00

Percentage passing sieve 90 - 100 0 - 10

Sieve the coarse aggregate on 10 mm and 5 mm and 5 mm sieves with square holes so that it is substantially free from oversized particles. 8.3.1.4.3

Standard sand to be used with standard coarse aggregate for making concrete cubes a)

Scope. Natural silica sand in five fractions. Each fraction shall comply with the grading requirements of table 5. For each fraction of sand, 8kg sand are required for sampling purposes and the sand shall be reduced using a sample divider to six sub-sample of about 500g each.

b)

Grading. The sand shall comply with the grading requirements of Table 8.3.3 below:

Table 8.3.3 Grading of sand fractions for concrete cubes 100mm or 70.7 mm

Test sieve 3.35 mm 3.35-2.36 mm 2.36-1.18mm 1.18mm-600 mic 600mic-300mic 300mic-150mm 150-90 mic 75 mic

Fraction A

Fraction B

Fraction C

Fraction D

Fraction E

% passing 100 90-100 0-10 0 0 0 0 0

% passing 100 100 90-100 0-10 0 0 0 0

% passing 100 100 100 90-100 0-10 0 0 0

% passing 100 100 100 100 90-100 0-15 0 0

% passing 100 100 100 100 100 85-100 0-15 0

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8.3.2

Compressive Strength Procedure using the 100 mm Concrete Moulds

8.3.2.1

Proportionship of materials. The masses of the individual materials for batches of six, nine of twelve cubes are given in Table 8.3.1 and 8.3.4. Table 8.3.4 Mass for individual fractions of sand (in grams) Fraction Mass for 6 Mass for cubes 9 cubes A (2.36-1.18mm) 550±5 800±5 B (1.18-600 micron) 1100±5 1600±5 C (600 micron-300 micron) 1650±5 2400±5 D (300 micron-150 micron) 1375±5 2000±5

8.3.2.2

Mass for 12 cubes 1050±5 2100±5 3150±5 2625±5

Mixing. Place the weighed materials in the mixer in the following order: 1. Sand, 2. Cement, 3. Coarse aggregate Hold the mixing water ready and start the mixer. After 15s add the water uniformly during the next 15s, and then continue mixing for a total time of 180 plus or minus 5s. After the machine mixing, turn the concrete over in the pan a few times with a trowel to remove any slight segregation.

8.3.2.3

Compacting: Half fill the cube moulds as quickly as possible. Compact each mould with exactly 35 strokes of the compacting bar, uniformly distributed over the cross section of the mould. Place a further quantity of concrete in each mould to form the top layer and compact similarly. Then strike off the top of each cube and smooth with the trowel so that the surface or the concrete is level with the top of the cube. Complete the entire operation within 15 minutes from the completion of the mixing.

8.3.2.4

Storage of specimens. Immediately after preparation, place the moulds in single layer on a layer on a level surface in a moist curing chamber. In order to reduce evaporation, cover the exposed top of the cubes with a flat impervious sheet making contact with the upper edge of the mould. After 24h plus or minus 0.5h mark the cubes for later identification and remove from the moulds. Immediately submerge all specimens, except the ones to be tested at 24h, in the tank and arrange in such a way that the temperature variation specified in Table 1 is not exceeded. Leave the cubes in the tank until just prior to the test but ensure that the temperature of the water in the tank is maintained at 200C plus or minus 20C. Specimens to be tested at 24h are marked and demoulded 15 min to 20 min before the test and are covered with a damp cloth so that they remain in a moist condition. If the concrete has not achieved sufficient strength after 24h to be handled without fear of damage, delay the demoulding for a further 24h but state this in the test report.

8.3.2.5

Testing of specimens. Determine the compressive strength of the cubes, under the temperature and relative humidity conditions specified in Table 8.3.2 for the compression testing room, at the specified age, calculated from the time that water was added to the materials, by the applying load without shock in the testing machine. Ensure that all surfaces of the cube are clean and that no grit or any other particle rests on the surface receiving the load and centre the cube on the lower platen and ensure that the load will be applied to the two opposite cast faces of the cube. The rate of loading shall be about 0.25 N/mm2 per second using the auxiliary platens.

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Test the specimens within the following limits: 24h 3 days 7 days 28 days

plus or minus 0.5h plus or minus 1.0h plus or minus 2.0h plus or minus 4.0h

8.3.2.6

Calculation. Calculate the average of the individual results of the set of three specimens tested at the same age, and express the result to the nearest 0.5N/mm2. If one result within the same set varies by more than 5% of the average of the set, discard the result and recalculate the average of the remaining results. If more than one result varies by more than 5% from the average, discard the set of results.

8.3.2.7

Report. Report the individual results and the average compressive strength to the nearest 0.5N/mm2, indicating if any result has been discarded.

8.3.3

Compressive Strength of Mortar Cubes using the 70.7 mm Mortar Cubes The strengths of cement is determined by compressive strengths tests on 70.7mm mortar cubes, made with specified sand, mixed by hand and compacted by means of a standard vibration machine. The equipment required for this test has been described in the general requirements for the compressive strengths of cement using 100mm concrete moulds. In addition to the equipment above there is a requirement for a vibrations machine. A typical vibration machine as shown in Fig. 8.3.3 is suitable. The temperature and humidity conditions required for the test are identical to those in the test for the compressive strengths of cement using 100mm concrete moulds.

8.3.3.1

Standard sand to be used for making mortar cubes. 8 kg of sand are required for sampling purposes and it shall be reduced using the sample divider into sub-samples of about 500g each. The moisture content of the sand shall not exceed 0.1% by dry mass using the ovendry method. The grading of the sand shall be such that all of it passes 850 micron test sieve and the proportion by mass passing the 600 micron test sieve shall not exceed 10%. The sand shall show a loss of mass not exceeding 0.25% on extraction with hot hydrochloric acid when determined in the following methods:

8.3.3.2

Method Dry a sample of little over 2g of the sand at a temperature of 1050C plus or minus 50C for a period of 1 h. Weigh a quantity of about 2g of the dried sand to an accuracy of plus or minus 0.001g into a porcelain dish and add 20ml of 1 M hydrochloric acid and 20ml of distilled water. Heat the dish on a water bath for 1h, filter the contents, and wash well with hot water. Dry the sand, ignite it in a covered crucible, cool it and weigh it again. The loss in mass shall be expressed as a percentage of the original mass of sample.

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8.3.3.3

Standard Test Procedures

Proportioning. The mass of cement, sand and water for each cube is given in Table 8.3.5. Table 8.3.5 Mixes for mortar cubes: Mix type Material Proportions by Mass for 1 cube mass Cement 1.0 185±1 V1 Sand 3.0 555±1 Water 0.40 74±1

8.3.3.4

Mixing. Before mixing, clamp the assembled mould on the table of the vibration machine and attach the hopper to the top of the mould. Mix the mortar for each cube separately on a non-porous surface that has been wiped clean with a damp cloth. Mix the cement and the sand dry, for 1 min, by means of the two trowels. Then add the water and mix the whole for 4 min with the two trowels.

8.3.3.5

Compacting. Please the whole of the mortar in the hopper of the mould by means of a suitable scoop as quickly as possible and compact by vibration for a period of 120s plus or minus 5s.

8.3.3.6

Storage. Storage of samples is identical with the procedure for test using 100mm concrete cubes.

8.3.3.7

Testing. The testing of the 70.7mm mortar cubes is the same procedure as the testing used for the 100mm concrete cubes except that the rate of loading shall be 0.60/Nmm2 per second. Calculations and reporting are identical to the corresponding sections of test using the 100mm concrete cubes.

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CHAPTER 9 TESTS ON CONCRETE

9.1

Slump Test

9.1.1

Scope The strength of concrete of a given mix proportion is seriously affected by the degree of its compaction. It is therefore important that the consistency of the mix is such that the concrete can be transported, placed and finished sufficiently easily and without segregation. A concrete satisfying these conditions is said to be workable. Workability is a physical property of the concrete depending on the external and internal friction of the concrete matrix; internal friction being provided by the aggregate size and shape and external friction being provided by the surface on which the concrete comes into contact with. Consistency of concrete is another way of expressing workability but it is more confined to the parameters of water content. Thus concrete of the same consistency may vary in workability. One test which measures the consistency of concrete is the slump test. It does not measure the workability of concrete but it is very useful in detecting variations in the uniformity of a mix of given nominal proportions. Mixes of stiff consistency have zero slump. In this dry range no variation can be detected between mixes of different workability. In a lean mix with a tendency to harshness a true slump can easily change to the shear slump or even to collapse. Different values of slump can be obtained from different samples of the same mix. Despite the limitations, the slump test is very useful on site as a check on the day-today or hour-to-hour variations in the materials being fed into the mixer. An increase in slump may mean, for instance, that the moisture content of aggregate has unexpectedly increased; another cause would be a change in the grading of aggregate, such as a deficiency in sand. Too high or too low a slump gives immediate warning and enables the mixer operator to remedy the situation.

9.1.2

Apparatus

9.1.2.1

Mould. A mould made of metal not readily attacked by cement paste and not thinner than 1.5mm. The interior of the mould should be smooth and free from projections such as protruding rivets and shall be free from dents. The mould shall be in the form of a hollow frustum of a cone having the following dimensions: a) diameter of base = b) diameter of top = c) height =

200mm plus or minus 2mm 100mm plus or minus 2mm 300mm plus or minus 2mm.

The base and top shall be open and parallel to the axis of the cone. The mould shall be provided with two handles at two-thirds of the height, and with foot pieces to enable it to be held steady. A mould which can be clamped to the baseplate is acceptable, provided that the clamping arrangement can be released without movement of the mould.

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9.1.2.2

Scoop, approximately 100mm wide.

9.1.2.3

Sampling tray, 1.2m x 1.2m x 50mm deep made from minimum 1.6mm thick noncorrodible metal.

9.1.2.4

Square mouthed shovel, size 2 in accordance with BS 3388.

9.1.2.5

Tamping rod, made out of straight steel bar of circular cross section. 16mm diameter, 600mm long with both ends hemispherical.

9.1.2.6

Rule, graduated from 0mm to 300mm at 5mm intervals.

9.1.3

Performing Slump test

9.1.3.1

Procedure. Commence the slump test as soon as possible after sampling of concrete as per standard procedure described in Chapter 2.

9.1.3.2

Preparation of sample for test. Empty the sample from the container onto the sampling try. Thoroughly mix the sample by shovelling to form a cone on the sampling tray. and turning this over to form a new cone, the operation being repeated three times. When forming the cone deposit each shovelful of the material on the apex of the cone so that the portions which slide down the sides are distributed as evenly as possible and so that the centre of the cone is not displaced. Flatten the third cone by repeated vertical insertion of the shovel across the apex of the cone, lifting the shovel clear of the concrete after each insertion.

9.1.3.3

Test. Ensure that the internal surface of the mould is clean and damp but free from excessive moisture before commencing the test. Place the mould on a smooth, horizontal, rigid and non-absorbent surface free from vibration and shock. Hold the mould firmly against the surface below. Using the scoop fill the mould in three layers, each approximately one-third of the volume of the mould when tamped. Tamp each layer with 25 strokes of the tamping rod, the strokes being distributed uniformly over the cross section of the layer. Tamp each layer to its full depth, ensuring that the tamping rod does not forcibly strike the surface below when tamping the first layer and only passes through the second and top layers into the layers below. Heap the concrete above the mould before the top layer is tamped. After the top layer has been tamped strike off the concrete level with the top of the mould with a sawing and rolling motion of the tamping rod. With the mould still held down, clean from the surface below any concrete which might have fallen onto it. Remove the mould from the concrete by raising it vertically, slowly and carefully, in 5 seconds to 10 seconds, in such manner as to impart minimum lateral or torsional movement to the concrete. The entire operation from start to finish shall be carried out without interruption and shall be completed within 150 seconds. Immediately after the mould is removed, measure the slump to the nearest 5mm by using the rule to determine the difference between the height of the mould and of the highest point of the specimen being tested. Note.

The workability of a concrete mix changes with time due to the hydration of the cement, and loss of moisture.

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Standard Test Procedures

Expression of result

9.1.3.4.1 General. The test result is only valid if it yields a true slump. The slump should be reported to the nearest 5mm and the type of slump (i.e. true, shear or collapse) should be stated as shown in Figure 9.1.1 a), b) and c). 9.1.3.4.2 Precision. For slump measurements made on concrete taken from the same sample, the repeatability is 15mm at the 95% probability level, for normal concrete having a measured slump within the range of 50mm to 75mm. 9.1.4

Report The following information shall be included in the report: a) b) c) d) e) f) g) h) i) j) k) l)

Name of testing agency Client Contract name Location of concrete in structure Supplier of concrete Date and time of test Time of completion of test Location of test Time lapsed from sampling to commencement of test Form of slump, whether true, shear or collapse Measure of true slump Name and signature of sampler and tester

A form of reporting the slump test results is shown in Form 9.1.1.

Figure 9.1.1

True Slump

a)Intact and symmetrical

Shear

b)

Shear

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c)

Collapse

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9.2

Crushing Strength of Concrete

9.2.1

Introduction Crushing tests are universally used for determining the strength of concrete and the standard test measures the crushing strength at an age of 28 days after mixing. Because of the time delay in obtaining the test results for concrete crushing strength, it is often very difficult or expensive to take remedial action if the test results are unsatisfactory. It is, therefore, essential to continuously control all aspects of concrete production so that the concrete very rarely fails in crushing strength tests. Crushing strength tests may be carried out on either cylinders or cubes made in standard moulds, cured under standard conditions and crushed in a standard manner. Any variations in the methods of manufacture, curing or testing may affect the final results and all these aspects require careful control.

9.2.2

Scope The results of this test may be used as the basis of concrete proportioning, mixing and placing operations; determination of compliance with specification, control for evaluating effectiveness of admixtures and similar uses. There are only minor differences in test methods between cubes and cylinders and they are, therefore, considered together.

9.2.3

Testing machine Crushing machines may vary from small hand-operated models to large power-driven universal test machines. In the large majority of machines, the load is applied by a hydraulic jack and the load is measured by a pressure gauge calibrated directly in units of force. Even a small crushing machine is likely to be one of the most expensive pieces of equipment in the laboratory and it should be maintained strictly in accordance with the manufacturer’s instruction. In general, it should be installed in a dry place and should be kept clean at all times. The hydraulic reservoir or pump should be frequently topped up with the correct grade of hydraulic oil, (the use of ordinary motor oil may quickly ruin the machine). The maximum load on the gauge should never be exceeded and the machine should not be left under load for a prolonged time. Any oil leaks should be quickly reported and appropriate repairs carried out. A well maintained machine should last many years. The accuracy of new crushing machines will vary somewhat with the type of machine, a smaller machine may be expected to give less accurate results than a high-quality universal test machine. If machines are used frequently at loads close to their design capacity, their accuracy will suffer and it is a wise precaution to only use machines at loads up to 75 percent of their design capacity. With age the calibration of a machine may vary and all machines should periodically be re-calibrated using a load cell or a number of standard test specimens, a proportion of which are tested on a fully-standardised machine. If a replacement load gauge is fitted to a machine, re-calibration must be carried out. The steel platens on a crushing machine are designed to withstand very high stresses, they should, however, occasionally be checked for damage and the ball seating of the upper platen should be checked for cleanliness and freedom of movement.

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9.2.4

Standard Test Procedures

Sample preparation Samples for crushing strength tests should truly represent the concrete used in the works and must, therefore, be taken throughout the period when work is in progress. It will be clear that if all specimens are made from only one batch of concrete this may represent only a small fraction of the concrete used in the pour. If, however, one specimen is made from each of a number of different batches of concrete throughout the day the specimens will be more representative of the average concrete used in the pour. Samples for testing should be taken at random times throughout the day and it is best for the mix to be batted before any indication is given that tests are to be made. It is very easy for a mixer operator to produce ‘a good mix’ especially for the tests; the purpose of quality control testing is, however, to determine the true strength of the typical material used in the works. The samples for crushing strengths may be collected in a similar manner as for workability test (slump test). In fact, it is usual procedure to test part of the sample for workability and part for crushing strength. The specimens should be prepared immediately after sampling.

9.2.5

Making test cubes and cylinders Concrete cube or cylinder moulds are made of steel or cast iron and of sufficient strength to resist deformation, the inside faces and ends are machined to give smooth surfaces and tight fitting joints. The moulds are made in two halves which bolt together for ease of removing the samples and cleaning. Cylinder moulds are normally 150 mm in diameter and 300 mm high; cube moulds normally have 150mm sides. The moulds sit on heavy baseplates which are fastened to the moulds by clamps. There should be no dirt or hardened mortar on the faces or the flanges of the moulds before assembly, otherwise the sections will not fit together closely. These faces must be thinly coated with mould oil to prevent leakage during filling, and a similar oil should be provided between the contact surfaces of the bottom of the mould and the base. The inside of the mould must also be oiled to prevent the concrete from sticking to it. The sections must be bolted tightly together and the mould held down firmly on the baseplate. Any excess oil should be removed by wiping with a soft cloth as this may be detrimental to the concrete. The concrete should be placed in the mould using a scoop, taking care to ensure the concrete does not segregate. The concrete should be placed in layers, each layer being compacted before placing another layer. The purpose of the procedure is to achieve full compaction (i.e. maximum density); a drier mix may, therefore, need more compaction than a wet mix. The following procedures are considered the minimum requirements to ensure full compaction; dry mixes may require considerably more compaction than the minimum shown: Cubes: - Place concrete in three layers giving each layer at least 35 blows of a 25mm square blunt-ended tamping rod. Cylinders: - Place concrete in three layers, each approximately one-third the volume of the mould, giving each layer 25 strokes of a 16mm diameter round-ended tamping rod of 600mm length.

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As an alternative to the above procedures vibration may be used to fully compact the specimen. This may be done either on a vibrating table or using an immersion vibrator. On completion of compaction, excess concrete should be removed with a steel float and the surface floated off level with the top of the mould. It is preferably for the finished surface to be slightly proud of the mould especially if the mix is very wet. Care should be taken when floating off the top surface to ensure the surface is not devoid of fines or contains too much mortar, as far as possible the top surface should be of a similar consistency to the concrete in the mould. The moulds should not be moved at all within the first four hours after casting and it is preferable to leave them undisturbed for 24 hours. The reference number of the specimen may be marked on the surface of the concrete once this has started to set. 9.2.6

Curing specimens The conditions under which a specimen is cured can cause substantial variations in the final strength of the concrete. For example, a normal concrete cured entirely in air, will have a strength at 28 days about half that of the same mix cured in water. Similarly, a specimen cured in water at 130C will have a strength at 7 days about 70% of that of the same mix cured in water at 460C. Because of these variations, it is essential that all specimens are cured in a similar manner if strengths are to be compared. Immediately after casting, the moulds should be covered with damp hessian (jute bags), the hessian should not be so wet as to allow water to fall on the surface of the specimen. It is a good practice to raise the hessian off the surface of the concrete by means of small pieces of wood. The moulds and hessian should then be covered with a sheet of polythene to prevent drying out. The polythene should completely enclose the moulds and be weighted down at the edges with bricks or stones. If polythene is not available, the hessian must be kept damp at all times. The moulds should not be exposed to direct sunlight. After 24 ± ½ hours, the specimens should be uncovered and removed from the moulds. The concrete is still weak at this stage and should be handled carefully. To remove from the mould, loosen all the bolts and clamps, slide off the baseplate and then tap the mould gently to free the specimen. On removal from the mould, the specimen should be put straight into a tank of clean water. It will not normally be possible to control the water temperature other than by shielding from direct sunlight but it should be normally within the range 25 to 350C. In the case of laboratory tests for trial mixes etc., the temperature should be maintained at 30± 10C. The water should be changed at least once a month. It should be noted that in the USA and Europe the standard curing temperature is 200C. In Bangladesh it is not normally possible to attain this temperature without artificial cooling and a standard temperature of 300C is used. This temperature difference has only a minor effect on 28-days strengths but results in a higher strength at 7 days. Care should, therefore, be taken when comparing test results with typical values given in reference books and papers.

9.2.7

Transporting specimens In many cases it will be necessary to transport cubes and cylinders from the site to a central laboratory where they are to be crushed. Specimens must not be transported

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during the first 24 hours after casting and, if possible, reduce the risk of damage during transit.

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Immediately prior to transport, the specimen should be removed from the curing tank and completely wrapped in hessian which should be at least two layers thick. The hessian and specimen should then be completely soaked with water and placed in a polythene bag which should be firmly sealed. A ticket containing details of the specimen should be placed in the bag. As an alternative to a polythene bag, the specimen may be placed in an airtight tin. Occasionally, purpose-made curing cans may be available, these have a sponge lining which is thoroughly wetted prior to inserting the specimen, thus dispensing with the need for hessian. The whole purpose in transporting is to keep the specimen wet at all times and to prevent physical damage during the journey. If the specimens are to be transported by lorry or over rough roads, additional protection may be required. On reaching the laboratory, the specimens should be immediately placed in a tank of water to complete the period of curing. 9.2.8

Testing specimens On completion of the required period of curing, the specimens are removed from the water, allowed to drain and surface-dried, using a soft cloth. The weight of the saturated surface-dry specimen is then determined, weight a. The weight of the sample in water is then taken by use of wire basket suspended from a suitable balance and immersed in a tank of water, weight b. Any burrs or edges on the sides of the specimen should then be removed using a carborundam block. The sample may now be tested. In the case of cubes, the sample is placed in the crushing machine on its side so that the two faces in contact with the platens of the machine are faces which were in contact with the polished steel sides of the mould, they should, therefore, be perfectly plane and smooth. Cylinders must, however, be tested in an upright position and the upper surface has only been float- finished. If the cylinder was crushed with the upper surface directly in contact with the platen of the test machine, the test result would almost certainly give a low result as the upper surface will be in contact with the machine at a number of high spots and compact stress patterns will be developed. It is, therefore, standard procedure to cap specimens prior to test. Capping may be done by a number of methods but the two most commonly used are neat cement and capping compounds. Using neat cement the cylinder is capped shortly after casting. During casting, the wet concrete should be left about 3mm. below the top of the mould. After at least 4 hours when the concrete has initially set, the mould is topped up with a neat cement paste. The cement paste should have been allowed to stand for some time prior to use, to allow some of the initial shrinkage to take place; it should not, however, have started to harden. To obtain a perfectly smooth surface the cement paste is finished off level with the top of the mould using a flat piece of glass which is slid across the top surface. It is sometime useful to apply a thin layer of graphite grease to the glass to aid sliding, some practice may be required before a perfectly smooth surface can be achieved. The specimen is then cured as usual. Using capping compound, the cylinder is capped immediately prior to testing. The capping compound may be pure sulphur or preferably a mixture of sulphur and milled fired clay (brick dust). The compound is heated in a metal pot until molten, when a portion is removed with a ladle, and poured onto a polished steel plate. The cylinder

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is then gently lowered onto the compound and rotated to ensure the face is completely

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covered. A special jig is normally used for this purpose, this ensures the cylinder is kept absolutely vertical during the capping operation. Once cool, the compound is immediately ready for use. After testing, compound may be recovered by re-heating. The capped cylinder is placed in the crushing machine. Specimens should be tested in a saturated surface-dry condition. The steel platens of the crushing machine are brought together until they just touch the upper and lower surfaces of the specimen. The specimen should be central on the platens and the upper platen should be free to rotate so that any small differences in alignment between the upper and lower surfaces of the specimen may be accounted for. The crushing machine should be fitted with a guard to contain the specimen on fracture. The load is then applied to the specimen at a constant rate to give an increase in stress on the specimen of 0.2 to 0.4 N/mm2/sec. On automatic machines the rate of loading may be shown by a load pacer, but on manual machines, pacing should be done using a stopwatch. It is a good practice to overlay the dial with a clear plastic sheet with times corresponding to each dial gauge reading shown. Note that, as the sample begins to fail the actual speed of the platens must be increased to maintain the same rate of application of load. The rate of loading has a significant effect on the test result in that, too quick a rate will give a high result and too slow a rate will give low results, it is, therefore, important to maintain the correct rate. The specimen is considered to have failed when the load begins to decrease, even though the operator is still attempting to maintain the rate of loading. Prior to this condition, small decreases in the load may take place and after a short time the load again increases, this re-orientation of the specimen close to failure may be disregarded. The maximum load attained during the test should be recorded. Some of the satisfactory and unsatisfactory of failures are shown in Figure 9.2.1 and Figure 9.2.2. 9.2.9

Calculation It is usual to test cubes and cylinders on a daily basis and the test results for a day’s work may be recorded on a sheet such as Form 9.2.1. The volume of the specimen is give by: Volume c = (weight a - weight b) ml Where, weight a, is weight of SSD specimen in air (grams) and weight b, is weight of SSD specimen in water (grams). The density of the concrete is give by: -

Density = =

Weight a = gm / ml Volume c a x 1000 kg / cu.m c MAY 2001

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The stress on the specimen is given by: -

Stress =

Maximum test load Cross - sectional area of specimen

In the case of a cube, the cross sectional area = L2.

π D2 4 Where L is length of side of a cube, D is diameter of a cylinder. In the case of a cylinder the cross sectional area =

The final results of a batch of cubes may be given on a form as shown in Form 9.2.2. 9.2.10

Reporting of results The crushing strength of the concrete should be reported to the nearest N/mm2 and the density of the hardened concrete should be reported to the nearest to kg/cu.m. The test report should include at least the following information: a) b) c) d) e) f) g) h) i) j) k) l) m) n) o) p) q) r) s) t)

Name of testing agency Client Contractor’s name Contract name Date and time specimens made Age of specimen at test Method of compacting specimens Sample identification number Conditions of curing and storage Supplier of concrete Date concrete delivered to site Location of concrete in structure Slump of concrete Maximum load at failure Density of specimen Appearance of concrete Description of failure Name of sampler Name of tester Any other information

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NOTE. All four exposed faces are cracked approximately equally, generally with little damage to faces in contract with the platens.

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Standard Test Procedures Form 9.2.1

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Standard Test Procedures Form 9.2.2

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

CHAPTER 10 TESTS FOR BITUMEN & BITUMINOUS MATERIALS 10.1

Bitumen Penetration Test

10.1.1

General requirements

10.1.1.1 Scope. This is a basic test for determining the grades of bitumen. In effect, the test is an indirect determination of high temperature viscosity and low temperature stiffness. The scope of this is to provide a method for determining the consistency of semi-solid and solid bituminous materials in which the sole or major constituent is either bitumen or tar pitch. 10.1.1.2 Definition. The penetration of bituminous material is its consistency expressed as the distance in tenths of a millimeter that a standard needle penetrates vertically into a specimen of the material under specified conditions of temperature, load and duration of loading. Grades of straight-run bitumen are designated by two penetration values, for example, 40/50, 60/80, 80/100 etc.; the penetration of an actual sample of the bitumen in any grade should fall between the lower and upper value given. 10.1.1.3 Apparatus a) The test apparatus consists of a right frame which holds the needle spindle in a vertical position and allows it to slide freely without friction. A dial gauge calibrated in millimeters measures the penetration. The total weight of the needle and spindle must be 50 ± 0.05 grams and facilities for adding additional weights of 50 ± 0.05 grams and 100 ± 0.05 grams must be provided. The surface on which the sample container rests must be flat and at right angles to the needle. b) A penetration needle made of fully hardened and tempered stainless steel of 1.00mm in diameter and 50mm in length, with one end ground to a truncated cone as shown in Figure 10.1.1. The needle is held by brass or stainless steel ferrule. The test is shown diagrammatically in Figure 10.1.1. c) The sample is placed in a metal or glass flat bottom container of the following dimensions:For penetrations below 200 mm: Diameter 55 mm Internal depth 35 mm For penetrations between 200 and 350 mm Diameter 70 mm Internal depth 45 mm The sample and dish are brought to the required temperature in a water bath which is maintained at a temperature within ±0.1/oC of the test temperature. The sample container must be placed on a perforated shelf which is between 50 and 100 mm below the surface of the water.

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DIAL GAUGE READS PENETRATION (in mm)

100 gms.

100 gms.

START

AFTER 5 SECS Penetration Test

0

1.00 to 1.02 mm

0

840’ to 940’

Approximately 50.8 mm (2’)

0.14 to 0.16 mm

Approx. 6.35 mm

Penetration Needle

Figure 10.1.1 Penetration needle

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d) To maintain the sample at the correct temperature during the test, a glass transfer dish is used. This dish of at least 350 ml capacity is fitted with a suitable support to hold the sample container firm and level during testing. e) A stopwatch is required to measure the time of penetration. 10.1.2

Sample preparation a) A sample of bitumen is first heated carefully in an oven or on a hotplate until it has become sufficiently fluid to pour. When using a hotplate, the bitumen should be stirred as soon as possible to prevent local overheating. In no case should the temperature be raised more than 900C above the softening point, and samples must not be heated for more then 30 minutes. b) When sufficiently fluid a portion of the sample is poured into the sample container to a depth of at least 10mm greater than the depth to which the needle is expected to penetrate. c) The sample is then covered loosely to protect against dust, and allowed to cool in the atmosphere between 15 and 300C for 1 to 1½ hours for the small container and 1½ to 2 hours for the large container. d) After cooling in air, the sample containers together with the transfer dishes should be placed in the water bath at the required temperature, for a period of 1 to 1½ hours for the small container and 1½ to 2 hours for the large container.

10.1.3

Conditions of test The test is normally carried out at a temperature of 250C with the total weight of the needle, spindle and added weights being 100 grams, the needle is released for a period of 5 seconds. If it is not possible to obtain these conditions or if there are special circumstances, one of the following alternative conditions may be used:Temperature, 0 C (0F) 0 (32) 4 (39.2) 46.1 (115)

Total sliding weights, grams 200 200 50

Time, seconds 60 60 5

It will be noted that, to obtain the standard temperature of 250C in Bangladesh, cooling of the water bath is normally required, it may, therefore, be more convenient in many cases to use a temperature of 46.10C. 10.1.4

Test procedure a) The needle should be examined for damage or surface roughness; it should be dry and clean. To ensure the needle is perfectly cleaned, it should be wiped with a cloth soaked in toluene or another suitable bitumen solvent and then dried with a clean cloth. b) The clean needle should be inserted into the penetrometer apparatus and the total sliding weight made up to the required value, if necessary by adding additional weights. For example, if 100 grams is required, and the needle and spindle weigh 50 grams, an additional weight of 50 grams must be added. c) The sample container is then placed in the transfer dish complete with water at the required temperature from the constant temperature bath, the sample being completely covered with water at all times. The transfer dish is then placed on the stand of the apparatus.

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d) The penetrometer needle is then slowly lowered until it just touches the surface of the sample. This point is best judged by using a strong source of light and determining the point where the tip of the needle just meets its image reflected by the surface of the sample. The initial dial gauge reading is taken. e) The needle is then released for the specified time and re-locked immediately at the end of the period. Care should be taken not to disturb or jolt the apparatus when releasing the needle, if this occurs or the sample moves, the test must be repeated. The final dial gauge reading is taken. f) The transfer dish should then be returned to the water bath and a clean needle fitted to the machine. The test is then repeated on the same sample. This procedure is repeated so that at least 3 determinations are made on each sample, taking care that each point is at least 10mm from the side of the sample container and at least 10mm from the other determinations. If the penetration exceeds 200mm, the needles should be left in the sample until all three determinations have been completed. 10.1.5

Calculation The penetration is given by: Penetration = (Initial dial gauge reading (mm) - Final dial gauge reading (mm)) x 10 A typical worksheet is shown as Form 10.1.1. The three penetration values obtained on the sample must agree to within the following limits:Penetration Maximum difference between highest and lowest determination

0 to 49

50 to 149

150 to 249

250

2

4

6

8

If the differences exceed the above values, the results are ignored and the test must be repeated on the second sample. If the differences are again exceeded by the second sample, the results must be ignored and the test completely repeated. If the determinations are within the above tolerances, the penetration is quoted as the average of the individual results. 10.1.6

Test report The report shall contain at least the following information: a) b) c) d) e)

Identification of the material tested A reference to the test method used. A statement of any deviation from the method stated for 25C/100g/5 seconds. The test result Date of test.

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Chapter 10 Tests For Bitumen & Bituminous Materials 10.2

Bitumen Softening Test

10.2.1

General Requirements

Standard Test Procedures

10.2.1.1 Scope. An alternative to the penetration test for checking the consistency of bitumen, is the ring and ball softening point test. The scope of this test is to provide a method for determining the consistency of semi-solid and bituminous materials in which the sole or major constituent is either bitumen or tar pitch. 10.2.1.2 Definition. The softening point of a bituminous material is the temperature at which the material attains a certain degree of softness under specified conditions of test. 10.2.1.3 Equipment. The equipment required to carry the penetration test in the laboratory are listed below: a) A steel ball having a diameter of 9.3 mm and weighing 3.5g ± 0.05g. b) Tapped ring, made of brass (see Figure 10.2.1) shall be used for referee purposes. For other purposes either a straight ring (Figure 10.2.2) or a shouldered ring (Figure 10.2.3) may be used. c) A convenient form of ball contouring guide (Figure 10.2.4) d) Ring holder made of brass or other metal (see Figure 10.2.5) e) Bottom plate made of brass or other metal (see Figure 10.2.6) f) A thermometer (capacity 1000C and accuracy 0.1 0C) g) A water bath of heat-resistant glass and conforming to the dimensions given in Figure 10.2.7, the rings being supported in a horizontal position. The bottom of the bulb of the thermometer shall be level with the bottom of the rings and within 10mm of them but not touching them. A 600 ml beaker is suitable. h) Distilled water for materials of softening points of 800C and glycerol for materials of higher softening point. i) Stirrer. 10.2.2

Sample preparation The sample obtained in accordance with section 2.7 is heated carefully in an oven or on a hotplate until it has become sufficiently fluid to pour. When using a hotplate, the bitumen should be stirred as soon as possible, to prevent local over-heating. In no case should the temperature be raised more than 900C above the expected softening point and samples must not be heated for more than 30 minutes. The brass rings to be used for the test are placed on a flat smooth brass plate, which has been coated immediately prior to use, with a thin covering of a mixture of glycerin and china clay. The coating is to prevent the bitumen sticking to the plate. When the bitumen is sufficiently fluid to pour, the rings should be filled with bitumen. A tight excess of bitumen should be used. The bitumen is allowed to cool for a minimum of 30 minutes. If the bitumen is soft at room temperature, it must be cooled artificially for a further 30 minutes. After cooling the excess material on the top of the specimen must be cut off cleanly using a moral palette knife. If further specimens are to be prepared or the test repeated, it is essential to use clean containers and to use bitumen which has not been previously heated.

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20.5 - 20.7

20.54 - 20.7 DIA 17.4 - 17.6 DIA

6.25 - 6.45

19 MIN.

15.78 - 15.96 DIA

2

2

6.25 - 6.45

15.76 - 15.96

OPTIONAL SHOULDER

18.9 - 19.1 DIA

Figure 10.2.1 Tapered Ring Material Brass

Figure 10.2.2 Straight Ring

22.9 - 23.1

15.76 - 15.96

2

2.7 - 2.9

6.15 - 6.45

19.74 - 19.94

18.9 - 19.1

Figure 10.2.3 Shoulder Ring All dimensions in millimetres.

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GUIDE FITS ON TOP OF RING (FIG. 1 OR 2) TO POSITION THE BALL ON CENTRE OF SAMPLE

Figure 10.2.4 Recommended Form of Ball Centring Guide 1.59 76 67

2 HOLES 6 DIA

HOLE 5.5 DIA

2 HOLES 19.2 DIA

Figure 10.2.5 Ring Holder 1.59

OUTLINE DIMENSIONS AS FIG. 10.2.5

2 HOLES TAP 2 BA

Figure 10.2.6 Base Dimensions in millimetres (inches).

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85 ID

LIQUID LEVEL

THERMOMETER 1P60C OR 1P61C

STEEL BALL 9.53 (3/8“) DIA WEIGHT 3.45-3.55 g

50

SHOULDERED RING FIG. 10.2.3

25

120

RING HOLDER FIG. 10.2.5

20-30

BASE FIG. 10.2.6

All DIMENSIONS IN MILLIMETRES

Figure 10.2.7 Assembly of ring-and-ball apparatus for two rings (stirrer not shown)

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Chapter 10 Tests For Bitumen & Bituminous Materials 10.2.3

Standard Test Procedures

Test procedure The apparatus is assembled with the rings, ball centering guides and thermometer in position and the beaker is filled with water to a depth of not less than 102mm and not more than 108mm. The water used for the test must be distilled and allowed to cool in a stoppered flask, this is to prevent air bubbles forming on the specimen during the test. The initial water temperature must be 5 ± 10C and this temperature must be maintained for 15 minutes, placing the beaker in a bath of iced water if necessary. On completion of the 15-minute period, the steel balls are positioned using forceps, and heat is applied to the beaker, preferably with a gas burner, at such a rate that the water temperature rises at 50C per minute. The rate of temperature rise is critical and if after the first 3 minutes the rise varies from the 50C in any minute period, by more than ± 0.50C, the test must be abandoned. As the temperature rises, the balls will begin to cause the bitumen in the rings to sag downwards, the water temperature at the instant the bitumen touches the bottom plate is taken for each ball. If the two temperatures differ by more than 10C, the test must be repeated using fresh samples.

10.2.3

Calculation The ring and ball softening point is simply the average of the two temperatures at which the bitumen just touches the bottom plate. A typical data sheet is shown as Form 10.2.1.

10.2.4

Test report The report shall contain at least the following information: a) b) c) d) e)

Identification of the material tested. A reference to the test method used. A statement offends deviation from the method. The test result [softening point is reported to the nearest 0.20C] Date of test

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Chapter 10 Tests For Bitumen & Bituminous Materials

10.3 10.3.1

Standard Test Procedures

Specific Gravity Test of Bitumen Introduction It is often required to know the specific gravity of straight run and cut-back bitumen for purposes of calculating rates of spread, asphaltic concrete mix properties etc. The standard specific gravity test is carried out at a temperature of 250C. However, if cooling facilities are not available, a temperature of 350C may be used, although this must be clearly stated in the result. For some purposes the specific gravity at elevated temperatures is required, as it is not possible to measure this directly an approximate value may be obtained by calculation using the value determined at a lower temperature.

10.3.2

Apparatus a) The apparatus for the test consists of a standard pycnometer as shown in Figure 10.3.1.

22 to 26 mm.

22 to 26 mm.

1.0 to 2.0 mm.

4.0 to 6.0 mm.

1.0 to 2.0 mm.

4.0 to 6.0 mm.

Figure 10.3.1 Suitable Pycnometers

b) A constant temperature water bath is also required. c) A 600 ml glass beaker.

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Chapter 10 Tests For Bitumen & Bituminous Materials 10.3.3

Standard Test Procedures

Sample preparation The sample obtained in accordance with Chapter 2 is heated carefully in an oven or on a hotplate until it has become sufficiently fluid to pour. When using a hotplate, the bitumen should be stirred as soon as possible to prevent local overheating. In no case should the temperature be raised more than 900C the softening point and sample must not be heated for more than 30 minutes.

10.3.4

Test procedure a) The clean, dry pycnometer, complete with stopper, should be weighed to the nearest 0.001 gram., weight A. b) A 600 ml glass beaker should be partly filled with freshly boiled distilled water which has been allowed to cool in a stoppered flask. The beaker should then be immersed to a depth of at least 100mm. in a water bath which is maintained at the required temperature ± 0.10C for a period of at least 30 minutes. The top of the beaker should be above the level of the water in the bath. c) The weighed pycnometer should then be filled with the boiled distilled water and the stopper placed loosely in position, taking care to expel all air from the pycnometer. The pycnometer should then be submerged in the beaker of water to a depth above the stopper of at least 40mm and the stopper firmly pushed into position. The beaker and pycnometer must remain in the water bath for at least 30 minutes after which the pycnometer is removed. The top of the pycnometer should first be dried with one stroke of a dry clean cloth and the remainder of the pycnometer is then dried as quickly as possible prior to weighing, weight B. Note that if a droplet of water forms on the stopper after drying, the stopper should not be re-dried, the volume of water in the pycnometer on immediately, leaving the water is the required value, any subsequent changes should not affect the result. On completion of weighing the pycnometer should be thoroughly dried. d) The pycnometer is then filled about three quarters full with the sample of bitumen. The bitumen should be carefully poured into the pycnometer ensuring that no air becomes trapped below the bitumen and there are no air bubbles in the sample. The sample should be poured into the center of the pycnometer so that the sides or neck of the pycnometer above the level of the bitumen are not contaminated. The pycnometer and bitumen should then be allowed to cool in air for a period of at least 40 minutes, after which the weight is determined, weight C. e) The pycnometer is then topped up with the boiled distilled water and the stopper loosely placed in position, taking care to expel all air from the pycnometer. The pycnometer should then be submerged in the beaker of water to a depth above the stopper of at least 40mm and the stopper firmly pushed into position. The beaker and pycnometer must remain in the water bath for at least 30 minutes after which the top and sides of the pycnometer are dried as before, prior to weighing, weight D. f) At least two separate determinations should be made.

10.3.5

Calculation The specific gravity of the bitumen is given by:

S.G =

(C - A) (B - A) - (D - C)

The average value of two or more results should be quoted.

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A typical calculation sheet is included as Form 10.3.1. The specific gravity is valid only at the temperature of the test. If, however, the specific gravity is required at other temperature, the following approximate relationship should be used:S.G at temperature, T = (S.G at test temperature, t) - (0.0006 x (T-t)) 10.3.6

Reporting of results The specific gravity of the bitumen should be reported to three decimal places, together with the temperature of the test. If the specific gravity is calculated for any other temperature, the fact that this is an approximate calculated value should be stated.

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Chapter 10 Tests For Bitumen & Bituminous Materials 10.4 10.4.1

Standard Test Procedures

Bitumen Extraction Tests General requirements

10.4.1.1 Introduction. The properties of bituminous materials are dependent on the amount of bitumen used to coat the constant components of the mix. Properties like durability, compactibility, rutting, bleeding, ravelling, ageing, etc., are all properties that are controlled by the amount of bitumen in the mix. 10.4.1.2 Equipment. The equipment required for this test for a number of methods, are given under the appropriate test method used. 10.4.1.3 Safety. This test may involve hazardous materials, operation and equipment. Safety precautions must be exercised at all times. The inhalation of solvent fumes may be particularly harmful and therefore it is advised that the area where the extraction test is carried out is well ventilated and that an adequate extractor fan is provided. 10.4.1.4 Calibrations. The scales used in this test must bear a valid certificate of calibration when in use. Calibrations should be carried out at intervals not exceeding twelve months. 10.4.1.4.1 Balances and weights. Balances should be calibrated using reference weights once every twelve months. a) Balances should be checked daily before use by two point checks using stable weights of mass appropriate to the operating range of the balance. b) Recalibration at a frequency of less than twelve months is necessary if the daily balance check indicates a fault or the balance has been serviced. 10.4.1.4.2 Volumetric glassware. In-house calibration by weighting the amount of pure water that the vessel contains or delivers at a measured temperature is acceptable when used in conjunction with the corrections in BS 1797 and balances and weights that are in calibration and are traceable. Where the test method specifies class B glassware it is permissible to use uncalibrated class A glassware. 10.4.1.4.3 Centrifuges. It should be checked and recorded that the centrifuge is capable of producing sufficient acceleration. See section 10.4.2.2.2.1.k). The centrifuge speed controls should be calibrated at the speed of rotation at least every six months using a traceable tachometer. 10.4.1.4.4 Pressure gauges. Pressure gauges should be calibrated at least once every six months using a certified reference gauge. 10.4.1.4.5 Time. Calibration should be performed on all timing devices at least once every three months. 10.4.1.4.6 Thermometry. For this test stamped, mercury-in-glass thermometers conforming to BS 593 are sufficient. 10.4.1.4.7 Test sieves. Only test sieves with valid calibrations should be used.

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Standard Test Procedures

10.4.1.4.8 Bottle rotation machine. The speed of rotation of the bottles should be calibrated at least once per year. 10.4.1.4.9 Solvents : Solvents should comply with the relevant applicable standard appropriate to the type of solvent used. 10.4.1.5 Consumables. Solvents used in this test, depending on the method used, are normally 1,1,1 - trichloroethane, trichloroethylene, methyl chloride or methylene chloride. All solvents are harmful when inhaled for prolonged periods of time. 10.4.1.6 Sample preparation a) If the mix is not soft enough to separate with a spatula, place it in a large, flat pan and warm in a 110°C plus or minus 5°C oven only until it can be handled or separated. Split or quarter the material until the required mass of the sample is obtained. b) The size of the test sample shall be governed by the nominal maximum size of the aggregate in the mix. The mass of the sample must comply with the values given in Table 10.4.1 Table 10.4.1 Nominal maximum aggregate size, mm 4.75 9.5 12.5 19.0 25.0 37.5

Minimum mass of sample, kg 0.5 1.0 1.5 2.0 3.0 4.0

Note.

When the sample in the test specimen exceeds the capacity of the equipment used, for the particular method used, the test specimen may be divided into suitable increments, all increments tested, and the results appropriately combined for calculation of bitumen content.

Note.

If tests are to be performed on the recovered bitumen it is necessary to determine the moisture content of the mixture. Refer to section 10.4.1.7 for the determination of water content in a mix.

10.4.1.7 Determination of Water Content 10.4.1.7.1 Apparatus A suitable apparatus is shown in Figure 10.4.1. The apparatus should be calibrated and traceable as recommended in section 10.4.1.4. 10.4.1.7.1.1 Cylindrical container. It should be made from a non-corrodible or brass gauze of about 1 mm to 2 mm aperture size, or alternatively, a spun copper tube with a ledge at the bottom on which a removable brass gauze disc rests. The container is retained. By any suitable means, in position in the top two-thirds of metal pot. The pot is flanged and fitted with a secure cover and suitable jointing gasket. The cover is held in position so that the joint between the container and the cover is solvent tight. The essential features of the construction are shown in Figures 10.4.2 and 10.4.3.

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Standard Test Procedures

Water cooled reflux condenser

Graduated receiver

A A stopcock may be fitted at A if required

Cylindrical container (see figure 10.4.2) Metal pot (see figure 10.4.3)

Figure 10.4.1 Assembled apparatus for the hot extractor method

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10

Standard Test Procedures

∅A

10

B

A B

From 120 mm to 200 mm as appropriate From 120 mm to 250 mm as appropriate

All dimensions are in millimetres Figure 10.4.2 Cylindrical container for the hot extractor method

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Chapter 10 Tests For Bitumen & Bituminous Materials

Brass or welded steel cover

3

3

45

60

5

Standard Test Procedures

Six or eight slots equally spaced around circumference to take swivelling bolts 30

Gasket ring

35

5

Three pegs to take gauge cylinder

20

A

B

Brass or welded steel outer pot

A From 150 mm to 230 mm as appropriate B From 200 mm to 400 mm as appropriate All dimensions are in millimetres and are for guidance only. NOTE. This design has been found satisfactory but alternative designs may be employed.

Figure 10.4.3 Brazed brass welded steel pot for the hot extractor method

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Standard Test Procedures

10.4.1.7.1.2 Graduated receiver. This must conform to the requirements of type 2 of BS 756, or a receiver of similar type, suitable for use with solvents of higher density than water, but fitted with a stop cock so that the water may be drawn off into a Crow receiver as necessary. The receivers must be fitted with ground glass joints; in this case an adaptor may be necessary to connect the receiver to the cover of the pot. 10.4.1.7.1.3 Water-cooled reflux condenser with the lower end ground at an angle of approximately 450 to the axis of the condenser. 10.4.1.7.1.4 Heater such as an electric hotplate. 10.4.1.7.1.5 Solvent; trichloroethylne free from water. 10.4.1.7.2 Procedure 10.4.1.7.2.1 Take part of the sample that was put aside during the sample reduction for the determination of water content and divide it into two portions by quartering. Retain one portion in a closed container. 10.4.1.7.2.2 Weigh the other portion to the nearest 0.05% and place it in a well ventilated oven at 1100C plus or minus 100C for one hour. Reweigh this portion and if the loss in mass is less than 0.1% no further action is required. 10.4.1.7.2.3 If the loss in mass exceeds 0.1% weigh the portion that was retained and transfer it to a dry hot extractor pot. Alternatively place the sample in a gauze container before transferring it to the extractor pot. 10.4.1.7.2.4 Add sufficient solvent to permit refluxing to take place and then bolt on the cover with a dry gasket in position. Fit the receiver and condenser in place. Ensure an adequate flow of water through the condenser and heat to give a steady reflux action. 10.4.1.7.2.5 Continue heating until the volume of water in the receiver remains constant. 10.4.1.7.2.6 Measure the volume of water and record its mass. 10.4.1.7.2.7 Calculation and expression of results Calculate the water content as a percentage by mass of either original sample to the nearest 0.1% or the dried portions to the nearest 0.1%. 10.4.1.7.2.8 Reporting of results Report the results as indicated in 10.4.2.3. 10.4.2

Bitumen Extraction Test

10.4.2.1 Scope. This is a quality control test which provides methods of extracting the bitumen from the mixed material. The results obtained from the methods herein may be affected by the age of the material tested. For best results it is recommended that these tests be carried out on mixtures and pavements shortly after their preparation.

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Standard Test Procedures

10.4.2.2 Test methods 10.4.2.2.1 Method A; Centrifuge method 10.4.2.2.1.1

Equipment The equipment required for this test method are listed below: a) Oven, capable of maintaining the temperature at 110° C plus or minus 5°C b) Pan, flat and of appropriate size to heat the test specimens. c) Balance or scales capable of weighing a sample to an accuracy of 0.05% of its mass. d) Extraction apparatus, consisting of a bowl and an apparatus in which the bowl may be revolved at controlled variable speeds up to 3600 revolutions per minute. Refer to Figure 10.4.4. Note. Accessories must be fitted to the apparatus for catching and disposing of the solvent. The apparatus preferably shall be installed in a hood or an effective surface exhaust system to provide ventilation. Note. Similar apparatus of larger size from the apparatus shown in Figure 10.4.4 may be used. e) Filter rings, felt or paper, to fit the rim of the bowl.

10.4.2.2.1.2

Procedure a) Weigh the sample of mixed material to the nearest 0.05% of its mass and weigh the oven dried filter ring to the nearest 0.01g. Sample size should comply with the requirements of Table 10.4.1. b) Determine the moisture content of the material (if required ) in accordance with the method stipulated in 10.4.1.7. c) Place the test portion in the bowl. d) Cover the test portion in the bowl with trichloroethylene or other approved solvent and allow sufficient time for the solvent to disintegrate the test portion but time must not exceed 1 hour. Place the bowl with the sample and solvent in the extraction apparatus. Dry the filter ring to a constant weight in an oven at 110°C plus or minus 5°C and fit it round the edge of the bowl. Clamp the cover on the bowl tightly and place a container under the drain outlet of the apparatus to collect the extract. e) Start the centrifuge revolving slowly and gradually increase the speed to a maximum of 3600 rev/min until the solvent ceases to flow from the drain. Allow the machine to stop and add 200ml (or more as appropriate for mass of sample) trichloroethylene and repeat the procedure (not less than three times). Use sufficient solvent so that the extract is very nearly clear. The collected extract may be used for other tests. f) Carefully transfer the filter ring and all the residual aggregate in the centrifuge bowl into a tarred metal pan. Dry in air until the fumes dissipate, and then to a constant mass in an oven at 110°C plus or minus 5°C. Scrape all the filter which might have adhered to the filter into the residual aggregate and weight the filter and aggregate to the nearest 0.01g separately.

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Standard Test Procedures

BOWL

203.2 D.

9 .5

6.4

56.4

57 .2

127.0

30.2 35.7

41.3 D.

9.5

28.6 55.6

247.7 D. 108.0 D. 4.8 7.9

247.7 D.

5.6

1 REG. CAST ALLUMINUM BURNISH ALL OVER

COVER PLATE 1 REG. CAST ALLUMINUM BURNISH ALL OVER

152.4 D. 157.2 D.

NOTE. See table 3 for dimensional equivalent. All dimensions are in millimetres.

Figure 10.4.4 Extraction Unit Bowl (Method A)

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Standard Test Procedures

Calculation. Calculate the bitumen content using the equation: Bitumen content in grammes = ((W1 - W2) - (W3 + W4)) / (W1 - W2) Where, W1 is the total weight of the test portion, in grammes W2 is the weight of water in test portion in grammes W3 is the weight of the extracted mineral aggregate in grammes W4 is the mass of the mineral matter in the extract.

10.4.2.2.1.4

Expression of results. The bitumen content may be expressed as a percentage of weight of bitumen with respect total weight of mix or with respect to total aggregate in the mix. Bitumen content % by weight of total mix = (bitumen content in grammes / W1) x 100 or, Bitumen content % by weight of total aggregate = (bitumen content in grammes / (W2 + W3)) x 100 Note.

The residue of aggregate and filler may be used in the graduation of the sample.

10.4.2.2.2

Method B; Extraction bottle method

10.4.2.2.2.1

Equipment a) Metal bottles of capacity appropriate to the size of sample being tested, e.g. 600ml, 2.51, 71, 121, with wide mouths and suitable closures. Note. Bottles should not be filled to more than three - quarters full. b) Bottle roller which can rotate the bottles about their longitudinal axes at a speed of 20 plus or minus 10 rev / min. c) Pressure filter of appropriate size and an air pump for supplying oil - free air at a pressure of at least 2 bar. d) Filter papers to fit the pressure filter e) Volumetric flasks of appropriate capacity, e.g. 250ml, 500ml, 11, 21. f) A set test sieves g) Balance capable of weighing a sample to an accuracy of 0.01% of its mass h) Sample divider. i) Trays that can be heated without change in mass in which to dry recovered aggregate. j) Solvent; either dichloromethane (methylene chloride) or trichloroethylene. k) Centrifuge. 1. A typical centrifuge carries four buckets fitted with centrifuging tubes of at least 50 ml capacity and is capable of an acceleration of between 1.5 x 104 m/s2 2. The tubes should be closed with caps such that no loss of solvent occurs during centrifuging. 3. The times of centrifuging should be obtained from figure 10.4.6 of section 10.4.2.2.2.2 after calculating the acceleration, a in m/s2 developed in the machine in accordance with the following equation: a = 1.097 n2 x 10-5 Where, MAY 2001

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Standard Test Procedures

n, is the angular velocity measured in revs. per min. r is the radius in millimeters to the bottom of the tubes (internal) when rotating. l)

Recovery apparatus comprising a water bath with an electric heater capable of maintaining boiling water in the bath throughout the recovery procedure, round-bottomed flasks of 200ml or 250 ml capacity, a pressure gauge, a vacuum reservoir and a method of maintaining a reduced pressure, e.g. a vacuum pump. Refer to Figure 10.4.5.

Figure 10.4.5 Recovery apparatus showing necessary features m) Balance accurate to 0.001 g for weighing the flasks. n) Stopclock or watch o) Containers resistant to solvent attack each with narrow neck and tight fitting resealable lid. p) Desiccator to store the extraction flasks before weighing. 10.4.2.2.2.2

Procedure a)

b)

Weigh a test sample to the nearest 0.05% of its mass and place it in the metal bottle. To the same accuracy weigh sufficient silica gel to absorb any water present and add it to the bottle. The mass of the silica gel should be equal to the mass of water estimated to be present in the sample. The mass of the sample should comply with the requirements of Table 10.4.1. Measure and record the temperature of the solvent immediately prior to adding the required volume to the sample. The volume required shall give a solution of between 2% and 4% concentration of soluble binder. Note.

To estimate the total volume V of solvent required use the following formula : MAY 2001

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Standard Test Procedures

V = M SE / CS Where,

M is the mass of sample in grammes. SE is the estimate percentage of soluble binder in the sample CS is the required concentration of solution in %. The estimated volume V is rounded to the nearest 250 ml.

c)

Close the bottle, and roll on the bottle rolling machine for the specified time indicated in Table 10.4.2 and Table 10.4.2a.

Table 10.4.2.

Time required for extraction (extraction Bottle method : binder determination by difference) Type of material Tars min Bitumens Min Macadams other than dense, close, medium or 30 10 fine graded. Macadams containing ut-back bitumens. Rolled asphalt, dense tar surfacing, dense, 60 20 close, medium and fine graded macadams containing penetration grade bitumens

Table 10.4.2a. Time required for extraction (extraction Bottle method : binder directly determined) Type of material Tars min Bitumens Min Macadams other than dense, close, medium or 30 10 fine graded. Macadams containing ut-back bitumens. Rolled asphalt, dense tar surfacing, dense, 60 20 close, medium and fine graded macadams containing penetration grade bitumens d)

Remove the closed bottle from the rolling machine and stand it upright for about 2 minutes to allow the bulk of the mineral matter to settle from suspension. Remove the stopper carefully and immediately transfer about 500ml of liquor to a clean dry pouring bottle. Transfer to the centrifuge tube sufficient liquid such that after centrifuging is complete there is enough solution to provide duplicate aliquot portions. Seal the remainder in the pouring bottle until aliquot portions are satisfactorily obtained. Seal the centrifuge tubes and centrifuge for the appropriate time given in Figure 10.4.6.

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Standard Test Procedures

30000 29000 28000 27000 26000 25000 24000 23000 22000 21000 20000 19000 18000 17000 16000 15000 15

16

17

18

19

20

21

22

23

24

25

26

27

28

29

30

Centrifuging time (minutes) Figure 10.4.6 Acceleration / time relationship for centrifuges

Note. From here on the work is done in duplicate. e) f)

Dry a flask and weigh it to the nearest 0.001g. Measure a sufficient amount of the centrifuged solution into the flask, using the burette to give a residue of 0.75g of soluble binder after evaporation of the solvent. Immediately prior to transfer from the centrifuge tube into a burette measure and record the temperature of the solution. Note 1. The difference between the temperature o f the solvent when measured in accordance with (b) and the temperature of the binder solution when measured in accordance with (f) should not exceed plus or minus 3°C. 2. If the temperature of (f) is outside the range of plus or minus 3°C of the temperature of the solvent gentle heating or cooling of the solution is permitted provided evaporation of the solvent is prevented. Note.

An estimate of the volume v of solution (aliquot portion) required is given by the following formula. V = (100 x V) / ( M SE )

Where, V is the total volume of solvent M is the mass of the sample in grammes. SE is the estimated percentage of soluble binder in the sample MAY 2001

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Standard Test Procedures

Volume V is rounded to the nearest 5 ml. g)

Remove the solvent from the binder solution by connecting the flask to the recovery apparatus, immersing the flask to approximately half its depth in boiling water, and distilling off the solvent. While the distillation is proceeding , gently shake the flask with a rotary motion so that the binder is deposited in a thin film layer on the walls of the flask. Do not allow pressure above atmospheric to develop in the flask during the evaporation of the solvent. Note. It is recommended that the distillation be carried out under reduced pressure. If reduced pressure is used the pressure should not be less than 600mbar.

h) At this stage frothing usually occurs, Proceed as follows : h.1) For penetration grade bitumen and tars reduce the pressure to between 180mbar and 220mbar in 1 min. to 2 min. and maintain at this pressure for a further 3 min. to 4 min. h.2) For cut-back bitumen allow the pressure to increase to approximately atmospheric pressure and then reduce in to between 550mbar in 1 min. to 2 min. and maintain at this pressure for a further 3 min. to 4 min. i) Remove the flask from the bath and admit air to the apparatus to increase the pressure to atmospheric. Wipe the flask dry and disconnect it, taking care to prevent the entry in to the flask of any water that may have collected at the joint between the flask and the stopper. Remove all traces of solvent that remain in the flask by a gentle current of clean, oil-free and water-free air at ambient temperature. Insert the air supply into the tube to below mid-depth. Clean the outside of the flask and remove any rubber adhering to the inside of the flask neck if rubber bungs are used. j)

10.4.2.2.2.3

Cool the flask in a desiccator and weigh to the nearest 0.001g. If the mass of the soluble binder recovered is not between 0.75g and 1.25g, repeat the procedure from (e) to (i). If the difference between the duplicate recoveries is greater than 0.02g reject and repeat the procedure from (e) to (i).

Calculations Calculate the soluble binder content S (%) of the mass of the original dry sample by means of the following equation : S = 10,000 (z V) / v M ( 100 - P ) ( 1 -z/dv ) Where, M is the mass of undried sample in grammes. z is the average mass of binder recovered from each of two aliquot portions in grammes. V is the total volume of solvent in millilitres. v is the volume of each aliquot portion in millilitres d is the relative density of the binder P is the percentage by mass of water in the undried sample. See 10.4.1.7.

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Chapter 10 Tests For Bitumen & Bituminous Materials 10.4.2.2.2.4

Standard Test Procedures

Washing of mineral aggregate

10.4.2.2.2.4.1 (filler directly determined) a)

b) c) d)

After removing sufficient solution for the determination of the soluble binder content, pour the liquid contents of the extraction bottle (including fine matter in suspension but taking care not to carry over any aggregate) through a 75 micron test sieve protected by a 1.18mm test sieve and through the funnel into the pressure filter. Fit the pressure filter with a filter paper. Pass the liquid through the filter paper under air pressure of at least 2 bar. Dry the sample by evaporation to constant weight. The sample is now ready for the gradation test.

10.4.2.2.2.4.2 (filler determined by difference) a)

b)

c)

After removing sufficient solution for the determination of the soluble binder content, pour the liquid contents of the extraction bottle (including fine matter in suspension but taking care not to carry over any aggregate) through a 75 micron test sieve protected by a.1.1m test sieve to waste. Shake the aggregate remaining in the bottle with further quantity of solvent (about half the quantity of solvent used originally). Immediately after shaking pour the solution through the nest of sieves, ensuring no loss of mineral matter. Repeat this process until no discoloration of the solvent is visible. At this point transfer the bulk of the contents of the bottle to a tray of suitable size and rinse the bottle once more to remove as much of the mineral matter as possible and pour the final washings through the 75 micron test sieve. Dry the sample by evaporation test. The sample is now ready for the gradation test.

10.4.2.2.2.5

Adjustments of soluble binder content and material passing 75 micron test sieve found on analysis. When assessing the composition of the mixture, adjust the found soluble binder and filler contents to correspond with the mid-point of the grading passing a 2.36 mm test sieve for rolled asphalt and a 3.35 mm test sieve for coated macadam. Use Table 10.4.3 for roadbase, basecourse and regulating course asphalt mixtures, Table 10.4.4 for wearing course asphalt mixtures and Table 10.4.5 for coated macadam roadbase and basecourse mixtures.

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Standard Test Procedures

Table 10.4.3

Adjustment values for roadbase, basecourse, and regulating course asphalt mixtures. Deviation of found Correction to Correction to content aggregate grading content of soluble of aggregate passing from mid-point binder 75 micron test sieve. passing 2.36mm test sieve 0 0.4 1.2 1.9 2.6 3.5 4.2 5.0 5.7 6.5 7.2 7.9 8.8 9.5 10.3 11.0

to to to to to to to to to to to to to to to to

0.3 1.1 1.8 2.5 3.4 4.1 4.9 5.6 6.4 7.1 7.8 8.7 9.4 10.2 10.9 11.7

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5

0 0.1 0.1 0.2 0.3 0.4 0.4 0.5 0.6 0.6 0.7 0.8 0.9 0.9 1.0 1.0

Table 10.4.4 Adjustment values for wearing course asphalt mixtures Deviation of found Correction to Correction to content aggregate grading content of soluble of aggregate passing from mid-point binder 75 micron test sieve. passing 2.36mm test sieve 0 0.5 1.6 2.7 3.8 4.9 6.0 7.1 8.1 9.2 10.3 11.4

to to to to to to to to to to to to

0.4 1.5 2.6 3.7 4.8 5.9 7.0 8.0 9.1 10.2 11.3 12.2

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

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0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

Page 10.29

Chapter 10 Tests For Bitumen & Bituminous Materials Table 10.4.5

Adjustment basecourse percentage 50% Deviation of found aggregate grading from mid-point passing 2.35mm test sieve 0 0.5 1.5 2.5 3.5 4.5 5.5 6.5 7.5 8.5 9.5

to to to to to to to to to to to

Standard Test Procedures

values for coated macadam roadbase and mixtures where the mid-point of the range of the passing the 3.35mm sieve lies between 30% and Correction to content of soluble binder

0.4 1.4 2.4 3.4 4.4 5.4 6.4 7.4 8.4 9.4 10.4

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

Correction to content of aggregate passing 75 micron test sieve.

0 0.1 0.3 0.4 0.6 0.7 0.9 1.0 1.2 1.3 1.5

10.4.2.3 Reporting of results The report shall contain at least the following information : a) b) c) d) e)

The testing laboratory. A unique serial number for the test report. The name of the client. Description and identification of the sample. Whether or not the sample was accompanied by a sampling certificate. An example data sheet is given as Form 10.4.1.

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Chapter 10 Tests For Bitumen & Bituminous Materials 10.5

Flash Point and Fire Point Tests of Bitumen

10.5.1

Introduction

Standard Test Procedures

Flash point of bitumen is the temperature at which, it’s vapour will ignite temporarily during heating, when a small flame is brought into contact with the vapour. The knowledge of this point is of interest mainly to the user, since the bitumen must not be heated to this point. The flash point tells the critical temperature at and above which suitable precautions are required to be taken to eliminate the danger of fire during heating. This temperature, however, is well below that at which the bitumen will burn. The latter temperature is called the fire point. 10.5.2

Definitions Flash point. It is the lowest temperature at which the vapour of a bituminous material momentarily takes fire in the form of a flash, under specified conditions of test. Fire point. It is the lowest temperature at which bituminous materials ignite and burn under specific conditions of test.

10.5.3

Scope This method covers the determination of the flash and fire points, by Cleveland Open Cup Tester, of petroleum products and other liquids, except fuel oils and those materials having an open cup flash point below (79 C) as determined by the Cleveland Open Cup Tester.

10.5.4

Apparatus a) Cleveland Open Cup Apparatus - This apparatus consists of the test cup, heating plate, test flame applicator and heater, thermometer support, and heating plate support, all conforming to the following requirement: Test Cup- of brass conforming to the dimensional requirements shown in Figure 10.5.3. The cup may be equipped with a handle. Heating Plate - A brass, cast iron, wrought iron, or steel plate with a center hole sur-rounded by an area of plane depression, and a sheet of hard asbestos board which covers the metal plate except over the area of plane depression in which the test cup is supported. The essential dimensions of the heating plate are shown in Fig. 10.5.2., however, it may the square instead of round, and the metal plate may have suitable extensions for mounting the test flame applicator device and the thermometer support. The metal bead, may be mounted on the plate so that it extends through and slightly above a suitable small hole in the asbestos board. Note.

The sheet of hard asbestos board which covers the heating plate may be extended beyond the edge of the heating plate to reduce drafts around the cup. The F dimension given is intended for gas apparatus. For electrically heated apparatus the plate shall be of sufficient size to cover the top of the heater.

Test Flame Applicator - The device for applying the test flame may be of any suitable design, but the tip shall be 1.6 to 5.0 mm or 0.06 to 0.20 in. in diameter at the end and the orifice shall have an approximate diameter of 0.8 mm or 0.031 in. The device for applying the test flame shall be so mounted to permit automatic duplication of the sweep of the test flame, the radius of swing being not less than MAY 2001

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Standard Test Procedures

150 mm or 6 in. and the center of the orifice moving in a plane not that 2.5 mm or 0.10 in. above the cup. A bead having a diameter of 3.8 to 5.4 mm or 0.15 to 0.21 in. may be mounted in a convenient position on the apparatus so the size of the test flame can be compared to it. Heater - Heat may be supplied form any convenient source. The use of a gas burner of alcohol lamp is permitted, but under no circumstances are products of combustion or free flame to be allowed to come up around the cup. An electric heater controlled by a variable voltage transformer is preferred. The source of heat shall be centered under the opening of the heating plate with no local superheating. Flame-type heaters may be protected from drafts or excessive radiation by any suitable type of shield that does not project above the level of the upper surface of the asbestos board. Thermometer Support - Any convenient device may be used which will hold the thermometer in the specified position during a test and which will permit easy removal of the thermometer form the test cup upon completion of a test. Heating Plate Support - Any convenient support will hold the heating plate level and steady may be employed. One form of the assembled apparatus, the heating plate, and the cup are illustrated in Figures 10.5.1, 10.5.2 and 10.5.3 respectively. Filling Level Gauge - A device to aid in the proper adjustment of the sample level in the cup. It may be made of suitable metal with at least one projection, but preferably two for adjusting the sample level in the test cup to 9 to 10 mm (0.35 to 0.39 in.) below the top edge of the cup. A hole 0.8 mm (1 / 32 in.) in diameter, the center of which is located not more than 2.5 mm or 0.10 in. above the bottom edge of the gage, shall be provided for use in checking the center position of the orifice of the test flame applicator with respect to the rim of the cup. (Figure 10.5.4 shows a suitable version.) b) Shield - A shield 460 mm (18 in.) square and 610 mm (24 in.) high and having an open front is recommended. c) Thermometer. 10.5.5

Preparation of apparatus a) The apparatus is supported on a level steady table in a draft-free room or compartment. The top of the apparatus is shielded from strong light by any suitable means to permit ready detection of the flash point. Tests in a laboratory heed (Note 1.) or any location where drafts occur are not to be relied upon. Note 1. With some samples whose vapours or products of pyrolysis are objectionable, it is permissible to place the apparatus with a shield in a hood, the draft of which is adjustable so that vapours may be withdrawn without causing air currents over the test cup during the final 56 C (100 F) rise in temperature prior to the flash point.

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

B THERMOMETER ASTM NO. 11C 1P 28C C D TEST FLAME APPLICATOR

RADIUS TEST CUP

A

E HEATING PLATE

F METAL BEAD

TO GAS SUPPLY HEATER (FLAME OR ELEC. RESIST. TYPE)

A - DIA. OF APLICATOR B - DIA. OF TIP C - DIA. OF ORIFICE D - RADIUS OF SWING E - INSIDE BOTTOM OF CUP TO BOTTOM OF THERMOMETER F - DIA. OF OPTIONAL COMPARISON BEAD

MILLIMETRES MIN MAX 5.0 1.6 5.0 (0.8 APPROX.) 150 -

MIN 0.06 (0.031 APPROX.) 6

(6.4 APPROX.)

(0.25 APPROX.)

3.8

5.4

INCHES

0.15

MAX 0.20 0.20 -

0.21

Figure 10.5.1 Cleveland open cup apparatus

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

F E D

C

A

B METAL

THERMAL INSULATION

MILLIMETRES A B C D - DIAMETER E - DIAMETER F - DIAMETER

MIN MAX 6.4 NOMINAL 0.5 1.0 6.4 NOMINAL 54.5 56.5 69.5 70.5 150 NOMINAL

INCHES MIN MAX 0.25 NOMINAL 0.02 0.04 0.25 NOMINAL 2.15 2.22 2.74 2.78 6 NOMINAL

Figure 10.5.2 Heating Plate

MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

J BRASS 45 0

I

H G FILLING MARK

F

E D

C

B A

MILLIMETRES A B C D - RADIUS E F G H I J

MIN MAX 67.5 69 62.5 63.5 2.8 3.6 4 APPROX. 32.5 34 9 10 1.8 3.4 2.8 3.6 67 70 97 101

INCHES MIN MAX 2.66 2.72 2.46 2.50 0.11 0.14 0.16 APPROX. 1.28 1.34 0.35 0.39 0.07 0.13 0.11 0.14 2.60 2.75 3.8 4.0

Figure 10.5.3 Cleveland Open Cup

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

A

C

B

F G E D

D A/2

A B C D E F

G

MILLIMETRES

INCHES

100 20 3.2 30 9 - 10 0.8 DIA. (2.5 MM ABOVE) BOT TOM EDGE 10

4 3/4 1/8 1-1/4 0.35 - 0.39 1/32 DIA. (0.10 IN. ABOVE BOTTOM EDGE) 3/8

NOMINAL NOMINAL NOMINAL NOMINAL NOMINAL MAXIMUM NOMINAL

Figure 10.5.4 Filling Level Gauge

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

b) The test cup is washed with an appropriate solvent to remove any oil or traces of gum or residue remaining from a previous test. If any deposits of carbon are present, they should be removed with steel wool. The cup is flashed cold water and dry for a few minutes over an open flame, on a hot plate, or in an oven to remove the last traces of solvent and water. The cup is cooled to at least 56 C (100 F) below the expected flash point before using. c) The thermometer is supported in a vertical position with the bottom of the bulb 6.4 mm (1/4 in.) from the bottom of the cup and located at a point halfway between the center and side of the cup on the diameter perpendicular to the arc (or line) of the sweep of the test flame and on the side opposite to the test frame burner arm. 10.5.6

Procedure a) The cup, is filled at any convenient temperature (Note 2) not exceeding 100 C or 180 F above the softening point, so that the top of the meniscus is at the filling line. To aid in this operation, a Filling Level Gauge (A7) may be used. If too much sample has been added to the cup, remove the excess, using a pipette or other suitable device; however, if there is sample on the outside of the apparatus, empty, clean and refill it. Any air bubbles on the surface of the sample (Note 3) are destroyed. Note 2.

Viscous samples should be heated until they are reasonably fluid before being poured into the cup. For asphalt cement, the temperature during heating must not exceed 100 C or 180 F above the expected softening point. Extra caution must be exercised with liquid asphalt’s which should be heated only to the lowest temperature at which they can be poured.

Note 3. The sample cup may be filled away from the apparatus provide the thermometer is preset with the cup in place and the sample level is correct at the beginning of the test. A shim 6.4 mm (1/4 in) thick is useful in obtaining the correction distance from the bottom of the bulb to the bottom of the cup. b) The test flame is lighted and adjusted to a diameter of 3.8 to 5.4 mm (0.15 to 0.21 in.). c) Heat is applied initially so that the rate of temperature rise of the sample is 14 to 17 C (25 to 30 F) per minute. When the sample temperature is approximately 56 C (100 F) below the anticipated flash point, decrease the heat so that the rate of temperature rise for the 28 C (50 F) before the flash point is 5 to 6 C (9 to 11 F) per minute. d) Starting at least 28 C (50 F) below the assumed flash point, the test flame is applied when the temperature read on the thermometer reaches each successive 2 C (5 F) mark. The test flame is passed across the center of the cup, at right angles to the diameter which passes through the thermometer. With a smooth, continuous motion apply the flame either in a straight line or along the circumference of a circle having a radius of at least 150 mm or 6 in. The center of the test flame must move in a plane not more than 2.5 mm or 0.10 in. above the plane of the upper edge of the cup passing in one direction first, then in the opposite direction the next time. The time consumed in passing the test flame across the cup shall be about 1 s. During the last 17 C (30 F ) rise in temperature prior to the flash point, care must be taken to avoid disturbing the vapours in the test cup by careless movements or breathing near the cup. MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Note 4.

Standard Test Procedures

If a skin should form before the flash or fire point is reached, move it carefully aside with a small spatula or stirring rod and continue the determination.

e) The observed flash point is recorded as the temperature read on the thermometer when a flash appears at any point on the surface of the oil, but do not confuse the true flash with the bluish halo that sometimes surrounds the test flame. f) To determine the fire point, continue heating so that the sample temperature increases at a rate of 5 to 6 C (9 to 11 F). The application of the test flame is continued at 2 C (5 F) intervals until the oil ignites and continues to burn for at least 5 s. Record the temperature at this point as the fire point of the oil. 10.5.7

Correction for barometric pressure If the actual barometric pressure at the time of the tests is less than 715 mm of mercury, it is recorded and the appropriate correction is added from the following table to the flash and fire points, as determined. Barometric Pressure mm of Mercury 715 to 665

10.5.8

Correction deg C 2

deg F -

715 to 635

-

5

664 to 610

4

-

635 to 550

-

10

609 to 550

6

Calculation and report 1. The observed flash point or fire point, or both is corrected in accordance with 10.5.7. 2. The corrected flash point of fire point, or both is reported as the Cleveland Open Cup Flash Point or Fire Point, or both.

10.5.9

Precision The following data should be used for judging the acceptability of results (95 percent confidence.) Duplicate results by the same operator should be considered suspect if they differ by more than the following amounts: Repeatability Flash point ..................................................................................................8 0C (15 0 F) Fire point .................................................................................................….8 0C (15 0 F)

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Chapter 10 Tests For Bitumen & Bituminous Materials 10.6

Viscosity Test of Bitumen

10.6.1

Introduction

Standard Test Procedures

Viscosity is reverse of fluidity. It is a measure of the resistance to flow. Higher the viscosity of liquid bitumen, the more nearly it approaches a semi-solid state in consistency. Thick liquid is said to be more viscous than a thin liquid of the road pavement. The bitumen binders of low viscosity, simply lubricate the aggregate particles instead of providing a uniform thin film for binding action, similarly high viscosity does not allow full compaction and the resulting mix exhibits heterogeneous character and thus low stability values. Saybolt Furol viscosity test is used to determine viscosity of liquid bitumens. 10.6.2

Scope In this test, time in seconds is noted for 60 ml of the liquid bitumen at specified temperature to flow through an orifice of a specific size. The higher the viscosity of the bitumen more time will be required for a quantity to flow out.

10.6.3

Apparatus a) Saybolt Viscometer and Bath. Viscometer- The viscometer, illustrated in Figure 10.6.1 shall be constructed entirely of corrosion resistant metal, conforming to dimensional requirements shown in Figure 10.6.1. The orifice tip, Universal or Furol may be constructed as a replaceable unit in the viscometer. Provide a nut at the lower end of the viscometer for fastening it in the bath. Mount vertically in the bath and test the alignment with a spirit level on the plan test; a small chain or cord may be attached to the cork to facilitate rapid removal. Bath- The bath serves both as a support to hold the viscometer in a vertical position as well as the container for the bath medium. Equip the bath effective insulation and with an efficient stirring device Provide the bath with a coil for heating and cooling and with thermostatically controlled heaters capable on maintaining the bath within the functional precision given in Table 10.6.2. The heaters and coil should be located at least 3 in. (75 mm) from the viscometer. Provide a means for maintaining the bath medium at least 6 mm (0.25 in.) above the overflow rim. The bath media are given in Table 10.6.2. b) c) d) e)

Withdrawal Tube, as shown in Figure 10.6.2 or other suitable device. Thermometer Support. One suitable design is shown in Figure 10.6.3 Saybolt Viscosity Thermometers, as listed in Table 10.6.1. Bath Thermometers - Saybolt Viscosity thermometers, or any other temperatureindicating means of equivalent accuracy. f) Filter Funnel, as shown in Figure 10.6.4 equipped with interchangeable 850 µm (N0. 20), 150µm (N0. 100) and 75µm (N0. 200) wire-cloth inserts meeting the requirements of M 92 with respect to the wire cloth Filter funnels of a suitable alternate design may be used. g) Receiving Flask, as shown in Figure 10.6.5 h) Timer, graduated in tenths of a second, and accurate to within 0.1% when tested over a 60min interval. Electric timers are acceptable if operated on a controlled frequency circuit.

MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials Table 10.6.1

Standard Test Procedures

Saybolt Viscosity Thermometer Thermometer

Standard Test Temperature, C (F) 21.11 (70)

Thermometer No. 17C (17F)

25.0 (77)

17C (17F)

37.8 (100)

18C (18F)

50.0 (122)

19C (19F)

54.4 (130)

19C (19F)

60.0 (140)

20C (20F)

82.2 (180)

21C (21F)

98.9 (210)

22C (22F)

Table 10.6.2 Standard Test Temperature, C (F) 21.1 (70) 25.0 (77) 37.8 (100)

Range C (F) 19 to 27 (66 to 80) 19 to 27 (66 to 80) 34 to 42 (94 to 108) 49 to 57 (120 to 134) 49 to 57 (120 to 134) 57 to 65 (134 to 148) 79 to 87 (174 to 188) 95 to 103 (204 to 218)

Subdivision C (F) 0.1 (0.2) 0.1 (0.2) 0.1 (0.2) 0.1 (0.2) 0.1 (0.2) 0.1 (0.2) 0.1 (0.2) 0.1 (0.2)

Recommended bath Media

Recommended Bath Medium

Max Temp Differential, C (F)

Bath Temperatures Control Functional Precision, C (F)

Water ± 0.05 (0.10) ± 0.05 (0.10) Water ± 0.05 (0.10) ± 0.05 (0.10) Water, or oil of 50 to 70 SUS ± 0.15 (0.25) ± 0.05 (0.10) viscosity at 37.80C (1000F) 50.0 (122) Water, or oil of 120 to 150 SUS ± 0.20 (0.35) ± 0.05 (0.10) viscosity at 37.80C (1000F) 54.4 (130) Water, or oil of 120 to 150 SUS ± 0.30 (0.50) ± 0.05 (0.10) viscosity at 37.80C (1000F) 60.0 (140) Water, or oil of 120 to 150 SUS ± 0.50 (1.0) ± 0.05 (0.10) viscosity at 37.80C 82.2 (180) Water, or oil of 120 to 150 SUS ± 0.80 (1.5) ± 0.05 (0.10) viscosity at 37.80C (1000F) 98.9 (210) Oil of 330 to 370 SUS viscosity at ± 1.10 (2.0) ± 0.05 (0.10) 37.80C *Maximum permissible difference between bath and sample temperatures at time of the test.

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

32.5 ± 0.5 (1.28 ± 0.02) 29.7 ± 0.2 (1.17 ± 0.01)

Overflow Rim

Level of Liquid in Bath

6 Min.

88 Min. (3.47) 125 ± 1 (4.92 ± 0.04) (0.354) 9.00 Bottom of Bath

(0.124 ± 0.008) 3.15 ± 0.02 (0.882 ± 0.04) 12.25 ± 0.1 (0.169 ± 0.012) 4.3 ± 0.3

Cork Stopper

Furol Tip

All dimensions are in millimitres (inches) Figure 10.6.1 Saybolt Viscometer with Furol or Fice

MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

¼ IN. NPS PIPE CAP

SILVER SOLDERED 6.4 (0.25) 0D

38 (1.5)

127 (5.0)

4.8 (0.19) 1 D

3.2 (0.13) 0 D 1.6 (0.06) 1 D Note : All dimensions are in millimetres (inches)

Figure 10.6.2 Withdrawal Tube for Use with Saybolt Viscometer

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

15.4 (0.63)

7.9 (0.31) 15.9 (o.63) 76 (3.0)

4.8 (0.19) 9.5 (0.37) 17.5 (0.69)

Note : All dimensions are in millimetres (inches) Figure 10.6.3 Thermometer Support

MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

A

A WIRE CLOTH

51 (2.0)

23 (0.91)

22 (0.87)

WIRE SPRING 8 CLOTH CLIP

1.6 (0.06)

6.4 (0.25)

95 (3.75)

13 (0.5) 33 (1.3) Note : All dimensions are in millimetres (inches) Figure 10.6.4 Filter Funnel for Use with Saybolt Viscometer

MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

10.6.4 Preparation of apparatus a) A Furol orifice tip is used for residual materials with efflux times greater than 25 s to give the desired accuracy. b) The viscometer is thoroughly cleaned with an appropriate solvent of low toxicity; then all solvent is removed from the viscometer and its gallery. The receiving flask is cleaned in the same manner. Note 1.

The plunger commonly supplied with the viscometer should never be used for cleaning; its use might damage the overflow rim and walls of the viscometer.

c) The viscometer and bath are set up in an area where they will not be exposed to drafts or rapid changes in air temperature, and dust or vapours that might contaminate a sample. d) The receiving flask (Figure 10.6.5) is placed beneath the viscometer so that the graduation mark on the flask is from 100 to 130 mm (4 to 5 in.) below the bottom of the viscometer tube, and so that the stream of oil will just strike the neck of the flask.

10 ±1 ID at Graduation Mark

60 ±0.05 ml 0 at 20C

58± 10

11 max.

3 min 3 min

Less Than 55

Note. All dimensions are in Millimetres

Figure 10.6.5 Receiving Flask e) The bath is filled to least 6 mm (1/4 in.) above the overflow rim of the viscometer with an appropriate bath medium selected from Table 10.6.2 f) Adequate stirring and thermal control are provided for the bath so that the temperature of a test sample in the viscometer will not vary more than ± 0.05 C (± 0.10 F) after reaching the selected test temperature. g) Viscosity measurements should not be made at temperatures below the dew point of the room's atmosphere. MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

h) For calibration and referee tests, the room temperature is kept between 20 and 30 0C (68 and 86 0F), and the actual temperature is recorded. However room temperatures up to 38 0C (100 0F) will not introduce errors in excess of 1%. 10.6.5

Calibration and standardization 1.

The Saybolt Furol Viscometer is calibrated at intervals of not more than 3 years by measuring minimum efflux time of 90s at 50 0C (122 0F) of an appropriate viscosity oil standard, following the procedure given in Section 10.6.6 Saybolt Viscosity Standards - The approximate Saybolt viscosity’s are shown in Table 10.6.3. Table 10.6.3

Saybolt Viscosity Oil standard

Viscosity Oil Standards S3 S6 S20 S60 S200 S600

SUS at 37.80C (1000F) 36 46 100 290 930 …

SUS at 98.90C (2100F) … … … … … 150

SFS at 500C (1220F) … … … … … 120

Standards Conforming to ASTM Saybolt Viscosity Standards -The viscosity standards may also be used for routine calibrations at other temperatures as shown in Table 10.6.3. Other reference liquids, suitable for routine calibrations may be established by selecting stable oils covering the desired range and determining their viscosities in a viscometer calibrated with a standard conforming to ASTM requirements. Routine Calibrations- The viscosity standards may also be used for routine calibrations at other temperatures as shown in Table 10.6.3.

2.

The efflux time of the viscosity oil standard shall equal the certified Saybolt viscosity value. If the efflux time differs from the certified value by more than 0.2% calculate a correction factor, F for the viscometer as follows: F = V/t Where, V = certified Saybolt viscosity of the standard, and t = measured efflux time at 500C (122 0F) Note 2. If the calibration is based on a viscosity oil standard having and efflux time between 200 and 600 s, the correction factor applies to all viscosity levels at all temperatures.

3.

Viscometers or orifices requiring corrections grater than 1.0% shall not be used in referee testing.

MAY 2001

Page 10.47

Chapter 10 Tests For Bitumen & Bituminous Materials 10.6.6

Standard Test Procedures

Procedure a)

b)

c)

d)

e)

The bath temperature is established and controlled at the selected test temperature. Standard test temperatures for measuring Saybolt Furol viscosity’s are 25.0, 37.8 50.0, and 98.9 0C (77, 100, 122, and 210 0F). A cork stopper is inserted having a cord attached for its easy removal, into the air chamber at the bottom of the viscometer. The cork shall fit tightly enough to prevent the escape of air, as evidenced by the absence of oil on the cork when it is withdrawn later as described. If the selected test temperatures is above room temperature, the test may be expedited by preheating the sample in its original container to not more than 1.7 0 C (3.0 0F) above the test temperature. The sample is stirred well, then strain it through a wire cloth of appropriate mesh directly into the viscometer until the level is above the overflow rim. The wire cloth shall be 150µm (No. 100) mesh except as noted in T 59 (Testing Emulsified Asphalt) and Note 3. For liquid asphaltic road materials having highly volatile components such as the rapid curing and medium curing cut-backs, preheating in an open container shall not be permitted. The material shall be poured at room temperature into the viscometer of if the material is too viscous to pour conveniently at room temperature, it shall be warmed sufficiently by placing the sample in the original container in a 50 0C (122 0 F) water bath for a few minutes prior to pouring. Filtering through a wire cloth shall be omitted. For tests above room temperature, greater temperature differential than indicated in Table 10.6.2 be permitted during the heating period, but the bath temperature must be adjusted to within the prescribed limits prior to the final minute of stirring during which the temperature of the sample remains constant. Note 3.

The viscosity of steam-refined cylinder oils, black lubrication oils, residual fuel oils and similar waxy products can be affected by the previous thermal history. The following preheating procedure should be followed to obtain uniform results for viscosity below 95 0C (200 0F). To obtain a representative sample, heat the sample in the original container to about 50 0C (122 0F) with stirring and shaking. Probe the bottom of the container with a rod to be certain that all waxy materials are in solution. Pour 100 ml into a 125 ml Erlenmeyer flask. Stopper loosely with a cork or rubber stopper. Immerse the flask in a bath of boiling water for 30 min. Mix well, remove the sample from the bath, and strain it through a 0.07µm (No. 200) sieve directly into the viscometer already in the thermostat bath. Complete the viscosity test within 1 hr. after preheating.

f)

The sample in the viscometer is stirred with the appropriate viscosity thermometer equipped with the thermometer support (Fig. 10.6.3) a circular motion at 30 to 50 rpm is used in a horizontal plane. When the sample temperature remains constant within 0.05 C (0.10 F) of the test temperature during 1 min of continuous stirring, the thermometer is removed. Note 4. Never attempt to adjust the temperature by immersing hot or cold bodies in the sample. Such thermal treatment might affect the sample and the precision of the test.

MAY 2001

Page 10.48

Chapter 10 Tests For Bitumen & Bituminous Materials g)

h) i)

10.6.7

Standard Test Procedures

The tip of the withdrawal tube is immediately placed (Fig. 10.6.2) in the gallery at one point, and suction is applied to remove oil until its level in the gallery is below the overflow rim. Do not touch the overflow rim with the withdrawal tube; the effective liquid head of the sample would be reduced. The receiving flask must be in proper position; then the cork is snapped form the viscometer using the attached cord and the timer is started at the same instant. The timer is stopped instant the bottom of the oil meniscus reaches the graduation mark on the receiving flask. The efflux time is recorded in seconds to the nearest 0.1 s.

Calculation and report 1. The efflux time is multiplied by the correction factor for the viscometer in 2 of 10.6.5. 2. The corrected efflux time is reported as the Saybolt Furol viscosity of the oil at the temperature at which the test was made. 3. Values to the nearest whole second are reported.

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

10.7

Distillation of Cut-Back Asphaltic (Bituminous)

10.7.1

Introduction By this procedure, the amount of the more volatile constituents in cut-back asphaltic products are measured. The properties of the residue after distillation are not necessarily characteristic of the bitumen used in the original mixture nor of the residue which may be left at any particular time after application of the cut-back asphaltic product. The presence of silicone in the cut-back may affect the distillation residue by retarding the loss of volatile material after the residue has been poured into the residue container.

10.7.2

Scope This test is used for the distillation of cut-back asphaltic (bituminous) products. Apparatus a) Distillation Flask, 500 ml side-arm, having the dimensions shown in Figure 10.7.1.

10 ±0 .5 mm 1.0 .1 .D to . 1.5 mm .W a ll

25±1.2 mm. 1.D.

102±2.0 mm. 0.D.

105±3 mm.

75±3

135±5 mm.

10.7.3

220 ±5

.0 m

m.

Figure 10.7.1 Distillation Flask

b) Condenser, standard glass-jacketed, of nominal jacket length from 200 to 300 mm and overall tube length of 450 ± 10 mm (see Figure 10.7.2). c) Adapter, heavy-wall (1 mm) glass, with reinforced top, having an angle of approximately 1050. The inside diameter at the large end shall be approximately 18 mm, and at the small end not less than 5 mm. The lower surface of the adapter shall be on a smooth descending curve from the larger end to the smaller. The inside line of the outlet end shall be vertical, and the outlet shall be cut or ground (not fire-polished) at an angle of 45 ± 5 deg to the inside line. d) Shield, 22 gauge sheet metal, line with 3-mm asbestos or high temperature light weight flexible ceramic insulation, and fitted with suitable transparent heat MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

resistant non-discoloring windows, of the form and dimensions shown in Figure 10.7.3 used to protect the flask from air currents and to reduce radiation. The cover (top) shall be made in two parts of 6.4-mm (1/4 in.) milboard. e) Shield and Flask Support- Two 150 by 150 mm sheets of 1.18 mm nickel-chrome mesh wire gauze on opening (16 mesh) on tripod or ring. f) Heat Source - Adjustable Terrill-type gas burner or equipment. g) Receiver - A 100 ml Crow receiver conforming to British Standard No. 658: 1962 (see Figure 10.7.4).

Thermometer Cork Stopper

Tight Ground Glass or Cork Joints

Window Shield 23 mm

Flask

15 mm

600 to 7 00 m m 450 mm

Two sheets wire gauge 6.5 mm

12.5 mm Chimney

Burner

Not less than 25.4 Water Jacketed condenser

Blotting paper Receiver

Stand

Figure 10.7.2 Distillation Apparatus

MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

148 ±3 mm 117± 2 mm

3.2± 0.3 mm 12.3±2 mm

30 ±10 mm 148 ±3 mm Cover in Two Parts

41±2 mm 117 ±3 mm

16±2 mm 82±3 mm

Two Windows are Provided at Right Angles to the End Slot.

6.4 ±0.5 mm

Windows Flanged Open-End Cylinder Made of 22-Gauge Sheet Metal Lined with 3 mm Asbestos Lining Riveted to Metal.

Shield

Figure 10.7.3 Shield

Figure 10.7.4 Crow receivers of capacity 25, 50 and 100 ml

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

h) Residue Container - A 240 ml (8 oz. seamless metal container with slip on cover of 75 ± 5 mm in diameter, and 55 ± 5 mm in height. Caution : Provide a cover suitable in size and material to extinguish a flame in the 240 ml (8 oz) tin box if the residue flames after pouring. i) j) 10.7.4

Thermometer. Balance as required.

Sampling a) The sample is thoroughly, stirred warming if necessary, to ensure homogeneity before removal of a portion for analysis. b) If sufficient water is present to cause foaming or bumping, dehydrate a sample of not less than 250 ml by heating in a distillation flask sufficiently large to prevent foaming over into the side arm. When foaming has ceased, the distillation is stopped. If any light oil has distilled over, separate and pour this back into the flask when the contents have cooled just sufficiently to prevent loss of volatile oil. The contents of the flask is thoroughly mixed before removal for analysis.

10.7.5

Preparation of apparatus a) The mass of 200 ml of the sample is calculated from the specific gravity of the material at 15.6 0C (60 0F). This amount is weighed ± 0.05 g into the 500 ml flask. b) The flask is placed in the shield supported by two sheets of gauze on a tripod or ring. The condenser tube is connected to the tabulator of the flask with a tight cork joint. The condenser is clampped so that the axis of the bulb of the flask through the center of its neck is vertical. The adapter is adjusted over the end of the condenser tube so that the distance from the neck of the flask to the outlet of the adapter is 650 ± 50 mm (see Figure10.7.2). c) The thermometer is inserted through a tightly fitting cork in the neck of the flask so that the bulb of the thermometer rests on the bottom of the flask. The thermometer is raised 6.4 mm (1/4 in.) from the bottom of the flask using the scale divisions on the thermometer to estimate the 6.4 mm (1/4 in.) distance above the top of the cork. d) The burner is protected by a suitable shield or chimney. The receiver is placed so that the adapter extends at least 25mm but not below the 100 ml mark. The graduate is covered closely with a piece of blotting paper, or similar material, suitably weighted, which has been cut to fit the adapter snugly. e) The flask, condenser tube, adapter, and receiver shall be clean and dry before starting the distillation. The 240 ml (8 oz.) residue container is placed on its cover in an area free from drafts. f) Cold water is passed through the condenser jacket. Warm water is used if necessary to prevent formation of solid condense in the condenser tube.

10.7.6

Procedure a) The temperatures to be observed are corrected in the distillation if the elevation of the laboratory at which the distillation is made deviates 500 ft (150 m) or more from sea level. Corrected temperatures for the effect of altitude are shown in Table 10.7.1 and 10.7.2. If the prevailing barometric pressure in millimeters of mercury is known, correct to the nearest 1 0C or 2 0F the temperature to be observed with the corrections shown in Table 10.7.3. Do not correct for the emergent stem of the thermometer.

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Table 10.7.1

Elevation above Sea Level. ft (m) -1000 (-305)

Corrected Fractionation Temperatures for Various Altitudes, Deg C Fractionation Temperatures for Various Altitudes. deg C 192

227

363

318

-500 (-152)

191

226

261

317

0(0)

190

225

260

316

500 (152)

189

224

259

315

1000 (305)

189

224

258

314

1500 (457)

188

223

258

313

2000 (610)

187

222

257

312

2500 (762)

186

221

256

312

3000 (914)

186

220

255

311

3500 (1067)

185

220

254

310

4000 (1219)

184

219

254

309

4500 (1372)

184

218

253

308

5000 (1524)

183

218

252

307

5500 (1676)

182

217

251

306

600 (1829)

182

216

250

305

6500 (1981)

181

215

250

305

7000 (2134)

180

215

249

304

7500 (2286)

180

214

248

303

8000 (2438)

179

213

248

302

36 2 36 1 36 0 35 9 35 8 35 7 35 6 35 5 35 4 35 3 35 2 35 1 35 0 34 9 34 9 34 8 34 7 34 6 34 5

Standard Test Procedures

Table 10.7.2

Elevation above sea level. ft (m) -1000 (-305)

Corrected Fractionation Temperatures for Various Altitudes, Deg C Fractionation Temperatures for Various Altitudes. deg C 377

440

503

604

684

-500 (-152)

375

438

502

602

682

0(0)

374

437

500

600

680

500 (152)

373

436

498

598

678

1000 (305)

371

434

497

597

676

1500 (457)

370

433

495

595

675

2000 (610)

369

431

494

593

673

2500 (762)

367

430

492

592

671

3000 (914)

366

429

491

590

669

3500 (1067)

365

427

490

588

667

4000 (1219)

364

426

488

587

666

4500 (1372)

363

425

487

585

665

5000 (1524)

361

423

485

584

663

5500 (1676)

360

422

484

582

661

600 (1829)

359

421

483

581

660

6500 (1981)

358

420

481

580

658

7000 (2134)

357

418

480

578

656

7500 (2286)

356

417

479

577

655

8000 (2438)

355

416

478

575

653

Table 10.7.3 Factors Calculating Temperature Corrections Nominal Temperatures. deg C (deg F) 160 175 190 225 250 260 275 300

Correction per 10 mm Difference in Pressure, deg C (deg F)

(320) (347) (374) (437) (482) (500) (527) (572)

0.514 (0.925 0.531 (0.957) 0.549 (0.989 0.591 (1.063) 0.620 (1.166) 0.632 (1.138) 0.650 (1.170) 0.680 (1.223) MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials 315.6 (600) 325 (617) 360 (680) •

Standard Test Procedures

0.698 (1.257) 0.709 91.277) 0.751 (1.351)

To be subtracted in case the barometric pressure is below 760 mm Hg: to be added in case barometric pressure is above 760 mm Hg.

Correction = (Observed Pressure - 760) x Correction per mm The correction per mm=1/10 the correction per 10 mm given the Table 10.7.3 Example :

Barometric observation temperature 260 C (500 F). Celsius Correction = (748-760) x 0.0632 = 0.758 Temperature = 260 - 0.758 = 259 C (rounded to nearest 10C) Fahrenheit Correction = (748 - 760) x 0.1138 = 1.366 Temperature = 500 - 1.366 = 498 F (rounded to nearest 20F)

b) Heat is applied so that the first drop of distillate falls from the end of the flask side-arm in 5 to 15 min. Conduct the distillation so as to maintain the following drop rates, the drop count to be made at the tip of the adapter: 50 to 70 drops per minute to 260 0C (500 0F) 20 to 70 drops per minute between 260 and 316 C (500 and 600 0F) Not over 10 minutes to complete distillation from 316 to 360 C (600 to 680 0F) c) The volumes of distillate are recorded to the nearest 0.5 ml in the receiver at the corrected temperatures. If the volume of distillate recovered is critical, use receivers graduated in 0.1 ml divisions and immersed in a transparent bath maintained at 15.6 ± 3 C (60 ± 5 0F). Note 1.

Some cut-back asphaltic products yield no distillate or very little distillate over portions of the temperature range to 316 0C (600 0F). In this case it becomes impractical to maintain the above distillation rates. For such cases the intent of the method shall be met if the rate of rise of temperature exceeds 5 0C (9 0F)/min.

d) When the temperature reaches the corrected temperature of 360 0C (680 0F), the flame is extinguished and the flask and thermometer are removed. With the flask in a pouring position, the thermometer is removed the contents is immediately poured into the residue container. The total time form cutting off the flame to starting the pour shall not exceed 15 s. When pouring, the side-arm should be substantially horizontal to prevent condense in the side-arm from being returned to the reside. Note 2.

The formation of skin on the surface of a residue during cooling entraps vapors which will condense and cause higher penetration results when they are stirred back into the sample. If skin begins to form during cooling, it should be gently pushed aside. This can be done with a spatula with a minimum of disturbance to the sample.

e) The condenser is allowed to drain into the receiver and record the total volume of distillate collected as total distillate to 360 0C (680 0F). f) When the residue has cooled until fuming just ceases, it is thoroughly stirred and poured into the receptacles for testing for properties such as penetration, MAY 2001

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viscosity, or softening point. Proceed as required by the appropriate IP method from the point that follows the pouring stage. g) If desired, the distillate, or the combined distillates from several tests, may be submitted to a further distillation. 10.7.7

Calculation and report a) Asphaltic Residue - Calculate the percent residue to the nearest 0.1 as follows: R = [(200 - TD)/200] x 100 Where, R = residue content, in volume percent, and TD = total distillate recovered to 360 0C (680 0F), ml. Report as the residue from distillation to 360 0C (680 0F), percent volume by difference.

b) Total Distillate - Calculate the percent total distillate to the nearest 0.1 as follows: TD percent = (TD/200) x 100 Report as the total distillate to 360 0C (680 0F), volume percent. c) Distillate Fractions i)

Determine the volume percentages of the original sample by dividing the observed volume (in milliliters) of the fraction by 2. Report to the nearest 0.1 as volume percent as follows: Up to 190 0C (374 0F) Up to 225 0C (437 0F) Up to 260 0C (500 0F) Up to 316 0C (600 0F)

ii)

Determine the volume percentages of total distillate by dividing the observed volume in millilitres to 360 0C (680 0F) and multiply by 100. Report to the nearest 0.1 as the distillate, volume percent of total distillate to 360 0C (680 0F) as follows : Up to 190 0C (374 0F) Up to 225 0C (437 0F) Up to 260 0C (500 0F) Up to 316 0C (600 0F)

d) Where penetration, viscosity, or other tests have been carried out, report with reference to this method as well as to any other method used. 10.7.8

Precision The following criteria shall be used for judging the acceptability of results (95 percent probability):

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a) Repeatability - Duplicate values by the same operator shall not be considered suspect unless the determined percentages differ by more than 1.0 volume percent of the original sample. b) Reproducibility - The values reported by each of the two laboratories shall not be considered suspect unless the reported percentages differ by more than the following: Distillation Fractions, volume percent of the original sample : Up to 175 0C (347 0F) above 175 0C (347 0F) Residue, Volume percentage by difference from the original sample

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3.5 2.0 2.0

Page 10.57

Chapter 10 Tests For Bitumen & Bituminous Materials 10.8

Float Test of Bitumen

10.8.1

Scope

Standard Test Procedures

This test is used to determine the floating time of bituminous materials. 10.8.2

Apparatus a) Float - The float (Figure 10.8.1 is made of aluminium or aluminium alloy in accordance with the following requirements :

Weight of float, g ................................. Total height of float, mm ..................... Height of rim above lower side of shoulder mm ........................................ Thickness of shoulder, mm ................. Diameter of opening, mm .....................

Min. 37.70 34.00

Normal 37.90 35.0

Max. 38.10 36.0

26.5 1.3 11.0

27.0 1.4 11.1

27.5 1.5 11.2

b) Collar - The collar (Figure 10.8.1) is made of brass in accordance with the following requirements :

Weight of collar, g ................................ Over all height of collar, mm ................ Inside diameter at bottom, mm ............. Inside diameter at top, mm .............

Min. 9.60 22.3 12.72 9.65

Normal 9.80 22.5 12.82 9.70

Max. 10.00 22.7 12.92 9.75

The top of the collar shall screw up tightly against the lower side of the shoulder. c) Calibration of Assembly - The assembled float and collar, with the collar filled flush with the bottom and weighted to a total weight of 53.2 g, shall float upon water with the rim 8.5 ± 1.5 mm above the surface of the water. This adjustment of the total weight of the assembly is for the purpose only of calibrating the depth of immersion in the testing bath. Dimension of the apparatus additional to those required above are given in Figure 10.8.1. d) Thermometer - Having a rang of - 2 to + 80 0C or + 30 to + 180 0F. e) Water Bath - 185 or more millimetres in its smallest lateral dimension and containing water 185 or more millimetres in depth. The height of the container above the water shall be 100 or more millimetres. The bath may be heated by either a gas or electric heater. A stand or other suitable support shall be available to hold the thermometer in the proper position in the bath during the test. f) Water bath at 5 0C - A water bath of suitable dimensions maintained at 5.0 ± 1.0 0 C, which may be accomplished by means of melting ice. g) Heater - An oven or hot plate, heated by electricity or gas, for melting samples for testing. h) Trimmer - A spatula or steel knife of convenient size. i) Plate - The plate shall be made of non-absorbent material of convenient size and of sufficient thickness to prevent deformation. The plate shall be flat so that the bottom surface of the collar touches it throughout. j) Timer - A stop watch or other timer graduated in divisions of 1 s or less.

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Standard Test Procedures

53 Ra .6 m d. m

Methods of sampling and testing

27.0±0.5 mm 35.0±1.0 mm

92.0± 2.0 mm Thermometer Float Tester

Tapered to make Weight

11.1± 0.1 mm

m m 95 ad. R

1.40±0.10 mm

1.4± 0.1 mm 12.0±0.5 mm Float (Aluminum) 9.70 ± 0.05 mm

Tripod

Standard Support

Bunsen Burner

1.40 ±0.10 mm

3 mm

Tapered to make Weight

22.5± 0.2 mm

Hot Bath

12.12 ±0.10 mm Collar (Brass)

Weight of Float, 37.90±0.20 g Weight of Collar, 9.80±0.20 g Assembly

Figure 10.8.1 Float Test Apparatus

10.8.3

Procedure a) The brass collar is placed with the smaller end down on the plate which has been previously coated with a suitable release agent (Note 1). Note 1.

Mixtures of glycerine and dextrine or talc (3 grams glycerine to about 5 grams dextrine or talc has been used satisfactorily), Dow-Corning Silicone Stop-Cock Grease, or castor oil-Versamid 900 [100:1 mixture by weight heated to 204 to 232 0C (400 to 450 0F) and stirred until homogeneous] have proven suitable. Other release agents may be used provided results obtained are comparable to those obtained when using one of the above .

b) The sample shall be completely melted at the lowest possible temperature that will bring it to a sufficiently fluid condition for easy pouring, excepting creosote-oil MAY 2001

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Standard Test Procedures

residues, which shall be mixed and poured at a temperature of 100 to 125 0C. Stir the sample thoroughly until it is homogeneous and free from air bubbles then pour it into the collar in any convenient manner until slightly more than level with the top. c) Asphalt and Asphalt Products - Asphalt and asphalt products are cooled to room temperature for 15 to 60 min. then place them for 5 min in the water bath at 5 0C, after which trim the surplus material flush with the top of the collar by means of a spatula or steel knife that has been slightly heated. Then the collar and plate are placed in the water bath at 5 0C and leave them in this bath for not less than 15 nor more than 30 min. d) The water is heated in the testing bath to the temperature at which the test is to be made. This temperature shall be accurately maintained without stirring, and shall at no time throughout the test be allowed to very more than 0.5 0C from the temperature specified. The temperature shall be determined by immersing the thermometer with the bottom of the bulb at a depth of 40 ± 2 mm below the water surface. e) After the material to be tested has been kept in the water bath at 5 0C for not less than 15 nor more than 30 min remove the collar with its contents from the plate and screw into the aluminum float. The assembly is completely immersed for 1 min in the water bath at 5 0C. Then the water is removed inside of the float and immediately float the assembly on the testing bath. Lateral drift of the assembly shall be permitted, but no spinning motion shall be intentionally imparted thereto. As the plug of material becomes warm and fluid, it is forced upward and out of the collar until the water gains entrance into the saucer and causes it to sink. f) The time, in seconds, between placing the apparatus in the water and the water breaking through the material shall be determined by means of a stop watch or other timer, and shall be taken as a measure of the consistency of the material under examination. 10.8.4

Precautions Special precautions should be taken to insure that the collar fits tightly into the float and to see that there is no seepage of water between the collar and float during the test.

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Chapter 10 Tests For Bitumen & Bituminous Materials 10. 9

Marshall Stability and Flow

10.9.1

Introduction

Standard Test Procedures

The Marshall test method is widely used for the design and control of asphaltic concrete and hot rolled asphalt materials, it cannot be applied to open textured materials such as bitumen macadam. Materials containing aggregate sizes larger than 20 mm, are liable to give erratic results. The full Marshall method is a method of bituminous mix design in addition to being a quality control test. The details given below related mainly to its use as a quality control test. The suitability of materials for the design of Marshall asphalt requires that a numbers of tests are performed on the materials. Tests normally performed are: 1. Asphalt : (a) Penetration (b) Viscosity (c) Solubility (d) Specific gravity (e) Fire & flash point (f) Softening point. 2. Aggregates : (a) Percent wear (b) Unit weight (c) Sieve analysis (d) Specific gravity (e) Absorption. The preliminary mix designs, the scheme for analysing aggregate will be governed, to some extent, by method of producing the gradation during construction. 10.9.2

Scope The basic Marshall test consists essentially of crushing a cylinder of bituminous material between two semi-circular test heads and recording the maximum load achieved (i.e. the stability) and the deflection at which the maximum load occurs (i.e. the flow). In common with many other tests, the bulk of the work is involved in preparing the samples for testing.

10.9.3

Apparatus The samples are prepared in 100 mm diameter moulds which are fitted with a base and collar (Figure 10.9.1) the sample is compacted using a hammer consisting of a sliding weight which falls onto a circular foot (Figure 10.9.2) during compaction the mould is held on a hardwood block which is rigidly fixed to a concrete base (Figure 10.9.3). The sample is removed from the mould using an extraction plate and press (Figure 10.9.1) and heated to the test temperature of 60° C in a water bath. The cylindrical specimens are tested on their sides between test heads similar to those shown in Fig. 10.9.4. The flow is measured with a dial gauge and the stability is measured with a proving ring. A motorised load frame is required for the test.

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Standard Test Procedures

∅ 114.3

∅ 38

∅ 101.6± 0.1

R 9.5 spherical seating

63.5

71.5 ∅ 99 ∅ 12.7

∅ 106.8±0.1

Extension collar

12.7 Extraction plate

∅ 106.4±0.1 ∅ 101.6±0.1

12.7

89

∅ 114.3

12.7

∅ 106.8±0.1

Mould cylinder

18.25

12.7

86

∅ 100.8± 0.1

∅ 104.8

∅ 125.4 5.6 Mould base Dimensions are in millimetres.

∅ 114.3 Extraction collar

Figure 10.9.1 Marshall Test Compaction and Extraction Equipment

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Standard Test Procedures

Handle screwed and pinned

457 ∅ 55

∅ 15.875

Mandatory requirements Diameter of foot 98.5 ±0 . 1 2 5 Length of free fall 457 Mass of sliding mass 4.535 kg (Other dimensions are approximate) 981 Sliding mass 4.535 kg 457 free fall Rod-nut screwed and riveted on end

305

25

∅ 45

Finger guard

70 3 Compression spring Free length 51 Wire diameter 3.175 Mean diameter 27.0 - 28.6 Number of coils 4

80 28

Foot screwed and locked 13

∅ 98.5

Hard face

Figure 10.9.2 Marshall Compaction Hammer

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Standard Test Procedures

Clamp ring Hinge post

Guide Post

Sample mould

Spring

Steel plate 300 x 300 x 25

Angle-housing welded to underface of steel plate to ensure permanent centering of assembly

Wood block 200 x 200 x 450

Barrel strainers (Min. Dia. 6.35)

25

Recess in concrete base of permanent centering of timber block or angle-housing bolted to concrete base 450 x 450 x 200

Concrete block 200

450 square

Mould base locating pegs NOTE. A suitable framework is secured to the pedestal to ensure that the compaction hammer is kept vertical.

Dimensions are in millimetres.

Figure 10.9.3 Marshall Compaction Pedestal

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Standard Test Procedures

Upper testing head

12.7 Guide pins and brushes

Lug for dial gauge

19 min. 101.6± 0.1

45 0

9.5 9.5 6.35

Dial gauge

76 Face hardened or plated and polished

Base

Lower testing head

NOTE. Frequent checks on inner radius of segments and on alignment of guide posts are necessary as high loads may permanently distort the testing head.

Swinging plate for dial gauge Dimensions are in millimetres.

Figure 10.9.4 Marshall Testing Heads

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Standard Test Procedures

10.9.4 Sampling Due to the various uses which may be made of Marshall tests, the materials for test may be obtained in one of the following forms: a) 100 mm diameter bituminous cores cut from an existing pavement using a core cutting machine. b) Ready-mixed bituminous material obtained from a mixing plant or at the point of laying, and sampled in accordance with Chapter 2. c) A sample of mixed aggregate obtained from the mixing plant together with a separate sample of bitumen obtained from the storage tank at the mixing plant in accordance with Chapter 2. Note.

A sample of mixed aggregate may be obtained from a mixing plant by batching the specified aggregate weights into the mixer but not allowing any bitumen to be batched. The aggregate sample is then discharged into a clean lorry where it may be sampled in accordance with Chapter 2.

d) Samples of the various sized aggregates in use at the mixing plant sampled in accordance with Chapter 2 together with a separate sample of bitumen sampled in accordance with Chapter 2. In the case of a sample of type (a), the core may be tested without further preparation. It must, however, be of the correct diameter and height. It is doubtful if samples obtained in this manner give results which are closely comparable to laboratory compacted specimens; however, the taking of cores is a valuable way to check the compacted density of the ‘as laid’ material and the small amount of additional work in determining the stability and flow is justified. If the densities obtained form cores (or sand replacement tests) are significantly below those of laboratory compacted specimens, attention should be paid to the methods of laying and compacting. For many quality control purposes samples of type (b) are the most useful as they may be conpacted, after re-heating in an oven to the required temperature. The delay between initial mixing and compacting should be as short as possible. With this type of sample separate test on the mixed aggregate will be required to determine the void content. It is essential to make frequent checks on the combined aggregate from an asphalt plant. The most important factors to be checked are the aggregate temperature at the time of mixing and the grading of the mixed aggregate. It may, therefore, be convenient to obtain separate samples of aggregate and bitumen (type (c) sample) and mix them in the required proportions in the laboratory. As the aggregate will be discharged from the mixer in a dry state, there is considerable risk of segregation and the greatest care should be taken in obtaining a representative sample. If there are reasons to suspect that the bitumen at the mixing plant has been overheated, it may be worth while to check the penetration as excessive heating hardens the bitumen. One particular use of this method of sampling is that if some adjustment is required to the bitumen content, a number of samples may be made at various bitumen contents to determine which is the most satisfactory. To maintain the quality of a bituminous material, it is necessary to check, at regular intervals, the various sizes of aggregate for grading, cleanliness, shape, strength etc. If it is required to study the effects of varying the aggregate, or bitumen proportions, it will be necessary to obtain separate samples of each MAY 2001

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aggregate size to be used in addition to a sample of the bitumen (a type (d) sample). 10.9.5

Sample Preparation If necessary, the aggregates should be oven-dried at 150°C before testing commences. (Sample types (c) and (d)). For samples of type (d) it is first necessary to combine the various sample sizes to give the required grading for the mixed aggregate. Several different gradings may be tried if a full Marshall mix design is to be carried out. When it is required to determine the most satisfactory bitumen content, given a sample of mixed aggregate, an initial estimate of the required bitumen content can be made from a knowledge of the compacted density of the Mixed Aggregate (CDMA). The CDMA is most conveniently determined using a standard 100 mm. diameter compaction mould and a 2.5 kg compaction hammer. The sample of dry aggregate is compacted in the mould in four layers, each layer being given 20 blows of the hammer. The density of the aggregate is then calculated in an identical manner to the bulk density in a compaction tests. The average of two determinations is taken as the CDMA, as shown in Form 10.9.1. It is also necessary to carry out separate determinations of the specific gravity of the mixed aggregate (SGMA), and the specific gravity of bitumen. The voids in mixed aggregate VMA are then determined from the formula:

(SGMA − CDMA SGMA

VMA =

X

100%

The VMA should normally be between 17 and 20% for a satisfactory mix. An initial estimate of the optimum bitumen content (B) is obtained from the formulae :

B100

=

( VMA

− VIM ) x S. G . Bitumen CDMA

Where, B100 is expressed in parts per 100 parts of mixed aggregate (p.h.a) and VIM = the specified percentage of air voids in the compacted mix. Note.

In bitumen calculations, it is usual to express all densities and specific gravities in gram/ml; gram/cc or Mg/cu.m.

Having completed the required tests on the mixed aggregates, the bituminous material is then produced by mixing the aggregates with the bitumen in the correct proportions. For each test specimen, the required weight of mixed aggregate is weighed out and place in an oven at the temperature shown in the following Table 10.9.1 (Column 2) :

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Table 10.9.1 Temperatures required in the preparation of moulded specimens 1 Binder grade pen (in mm)

80 - 100 60 - 70 40 - 50

2 Temperature

3

4

5

Immediately prior to compaction (max. - min.) °C 136 - 132 141 - 137 146 - 142

Heated aggregate

Heated binder bitumen

On Completion of mixing (approx.)

°C 155 160 165

°C 150 155 160

°C 140 145 150

The amount of aggregate required for each specimen is in the region of 1000 - 1500 grams, but the exact amount must be determined by an initial trial. There specimens are required for each bitumen content and the aggregate should be heated in the oven for at least 2 hours. The weight of bitumen required for each specimen should be weighed out into a small metal container, and heated to the temperature shown in the Table 10.9.1 (Column 3), using an oven or a hot plate. When using a hot plate, the bitumen should be stirred whenever possible to prevent local overheating and heating should not continue for longer than 30 minutes. The temperature should be maintained for at least 10 minutes. When pouring a sample of bitumen it is inevitable that some bitumen adheres to the sides of the container, to account for this, it is useful to beat a sample of bitumen in the container and pour this away, thus coating the sides of the container before adding the exact weight of bitumen required for the specimen, the weight of bitumen adhering to the sides of the container will vary only slightly each time it is emptied. To establish the exact weight of bitumen used, the weight of the container should be taken before heating and after pouring. The heated aggregate and bitumen should be thoroughly mixed together as quickly as possible. Mixing may be by hand or in a mechanical mixer. In either case the mixing pan and tools should be heated prior to use so that the temperature of the sample is maintained. When all the aggregate is evenly coated with the bitumen, the sample should be removed from the mixing pan and compacted as quickly as possible. When using a sample of mixed bituminous material (type (b)), this should be divided into the required specimen weights as quickly as possible after sampling and then brought back to the required mixing temperature by heating in an oven. The time of heating will depend on the initial temperature of the sample and should not exceed one hour. On removal from the oven, the sample should be compacted as soon as possible. The compaction moulds, collars and bases should be cleaned, lightly oiled and placed in an oven, at the temperature shown in column 5 of the Table 10.9.1, for a period of at least one hour. The hammer base should also be heated in a similar manner. The base, mould and collar should then be assembled and a 100 mm. diameter disc of tough non-absorbent paper (such as greaseproof) placed in the base of the mould. The whole of the mixed material is then transferred into the mould as quickly as possible and levelled by prodding with a spatula 15 times round the perimeter and 10 times over the interior of the sample. At the end of this process, the upper surface of MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

the sample should be slightly domed. At this stage the temperature should be checked, using a previously warmed thermometer, to save time, and must be within the range shown in column 5, Table 10.9.1. A disc of non-absorbent paper is then placed on the top of the sample, the mould assembly is placed on the compaction pedestal and located in the mould clamp. Compaction is then given to the top of the sample using 50 blows of the hammer. The hammer must be maintained perfectly vertical during this operation and the rate of compaction should be about 60 - 70 blows per minute. On completion of 50 blows, the collar and base are carefully removed, the mould is turned over and the base and collar re-fixed so the bottom of the sample is now facing upwards. The assembly is re-fixed in the pedestal mould holder and given another 50 blows of the hammer. On completion of compaction, the collar is removed and the mould and base are immersed in cold water for at least 15 minutes. When completely cool the base is removed and the sample ejected from the mould using the extraction apparatus. The specimen must be extracted from the mould without shock or distortion. Any burrs may be removed with a spatula or sharp knife. The specimen should be placed on a flat surface and the average height measured, preferably with a dial gauge, the height must be between 62.0 and 65.0 mm. (2.7/16” - 2.9/16) otherwise the sample should be discarded. The specimen is then dried with a cloth and stored on a piece of absorbent paper on a flat surface for at least 16 hours. Ensure the different specimens are clearly marked. The mould, base and collar should be thoroughly cleaned before re-use or storage. 10.9.6

Measurement of Density Prior to testing, it is necessary to determine the density of the density of the specimen, this is done by weighing in water. The weight of the dry specimen is first determined to an accuracy of 0.1 grams. Weight C. The specimen is then weighed in water, weight d, using a wire basket suspended from a suitable balance. Care should be taken to ensure that there are no air bubbles attached to the wire basket or the specimen prior to weighing. These weights are recorded on the data sheet Form 10.9.2 and the calculations relating to volume and voids in the mix may then be completed.

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Standard Test Procedures

From the weight of bitumen and aggregates used in the mix, the proportion of binder is calculated as follows:

Proportion of binder, B =

Weight of bitumen x 100...(a) Weight of mixed aggregate

Where B is expressed in parts of bitumen per 100 parts of aggregate (p.h.a) . This is the most convenient method of expressing binder content. The binder content as a true percentage of the mixed material, is given by:

B' =

Weight of bitumen x 100% (Weight of mixed aggregate) + (Weight of bitumen)

Note that

B' = B x

100 % (100 + B)

............... ( b)

Where, B is in p.h.a. From the weight in air and weight in water : Total Volume of specimen, V = (Weight c - Weight d) x S.G. water = (Weight c - Weight d) ml .......... (f) The density of the compacted specimen is then given by, Compacted density of mix,

Weight C V

CDM =

gram / ml ....................... (g)

The maximum theoretical density of the specimen if there were no air voids would be: Max. theoretical specimen density,

' X' =

100 % Bitumen % Aggregate + S.G . Bitumen S. G . M .A

or, ' X' =

100 B' (100 − B') + S.B.Bitumen S.G.M.A

gram / ml..................(h)

From the above results it is possible to derive a number of factors concerning the volumetric proportions of the mix and the void content:

Volume of binder, Vb =

B' x CDM % .............. (i) S.G. Bitumen

(as % of total volume) MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Volumeof aggregate, Vagg =

(100 − B') x CDM S. G. M. A

Standard Test Procedures

% ..............( j)

Volumeof air voids, VIM = (100 − Vb − Vagg ) % ..................(k) (as % of total volume) The voids in the mixed aggregate are given by : VMA

= (100 - Vagg) % ............... (l)

and this value may be compared with that calculated previously using the CDMA. The percentage of voids filled with bitumen are given by : VFB = 100 x

Vb % ....................................................... (m) VMA

and the percentage of air voids in the compacted mix, VIM

= 100 x ( 1 -

CDM ) % ........ (n) ' X'

This alternative method of calculating VIM may be used as a check. The values of VIM achieved should be compared with the specified value. If the test is being repeated using a number of different bitumen contents, it is usual to plot, graphs of compacted density of mix, CDM, Voids in Mix, VIM, and Voids filled with bitumen, VFB, against binder content, B. 10.9.7

Test procedure On completion of density measurements, the specimens are heated in a thermostatically controlled water bath at a temperature of 60 ± 0.5°C for a period of 60 minutes the specimens should be completely immersed in the water. The inside faces of the testing heads should be thoroughly cleaned and the guide rods lightly oiled, so that the upper head slides freely. The heads should then be immersed in the water bath at 60 ± 0.5°C so they are heated to the correct test temperature. It is important that the test is carried out quickly and efficiently such that the total time between removing the specimen from the water bath and completion of the test should not exceed 40 seconds. It is, therefore, essential that the test machine, gauges etc., are all prepared ready for use before removing the specimens from the water bath. On completion of the heating period, the specimen and heads should be quickly removed from the bath and the specimen placed on its side centrally in the lower test head, the upper head is then located on the slides and brought into contact with the specimen. The whole assembly is then placed on the test machine directly below the plunger. The deformation dial gauge should be placed into position and either zeroed or the initial reading taken. The load ring dial gauge should previously have been zeroed. The load is then applied to the specimen by the machine at a rate of 50.8 mm/minute ± 5%. The reading on the load ring gauge should be observed and the instant the load stops increasing, the machine should be switched off. The maximum load gauge MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

reading should be taken. The corresponding reading on the deformation (flow) gauge may then be taken. The heads should be wiped clean before testing further specimens. 10.9.8

Calculation The calculations concerned with densities and voids have already been described in section 10.9.6 From the maximum load gauge reading, the maximum load applied may be determined using a calibration chart or proving ring factor. This is the measured stability. It will be noted that the height of the specimen may vary somewhat and the measured stability will tend to increase as the height of the specimen increases. To reduce all measurements to a common height of 63.5 mm. (21/2 ins.) a stability correction factor is applied to the measured value such that:

Corrected stability = ( Measured stability ) x (Adjustment factor) The adjustment factor is determined from the specimen volume in accordance with Figure 10.9.5. The stability is expressed in kN (or 1bf). The flow value is simply the reading on the deformation gauge at the point of maximum load, and is expressed in mm. (or 0.01 inch). A useful factor in the assessment of mix quality is the stability to flow ration which is given by :

Stability flow ratio

=

Corrected stability Flow

The stability to flow is expressed in kN/mm or lb/(0.01 inch). The average value of the three specimens should be quoted. As mentioned previously the Marshall test is often carried out as a mix design procedure and specimens will be made at various bitumen contents to determine which is the most satisfactory (i.e. the optimum binder content). To determine the optimum binder content graphs of CDM, VIM, VFB, Stability and Flow against binder content are normally plotted as shown in Figure 10.9.6. The values of some these factors may be specified and the most satisfactory values for the other factors are generally known; it is, therefore, possible to obtain the most desirable bitumen content relating to each of these factors from the relevant graph. These values are not likely to be exactly the same, but are generally fairly close. The optimum bitumen content may than be determined by taking an average of these different values.

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Standard Test Procedures

10.9.9 Reporting of results The stability should be reported to the nearest 0.1 kN (20 lbsf) and the flow should be reported to the nearest 0.5 mm. (0.01inch). The bitumen content of the specimen, the grade of bitumen and the proportions of the various aggregate sizes used should be given.

Height

of

specimen,

Volume of specimen, ml

Stability factor

502 - 503

1.04

504 - 506

1.03

507 - 509

1.02

510 - 512

1.01

513 - 517

1.00

515 - 520

0.99

512 - 523

0.98

524 - 526

0.97

527 - 528

0.96

correction

mm

62

63.5

65

Figure 10.9.5 Correction factors for stability values with variations in height or volume

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Standard Test Procedures

Density (CDM) 2000 Stability (Lbs)

2.3

1500

2.2

1000

2.1

500 4.5

5.0

5.5

6.0

6.5

7.0

7.5

4.5

5.0

Binder Content (pha)

5.5

6.0

6.5

7.0

7.5

Binder Content (pha) 90

Voids In Mix (V.I.M.)

Voids Filled with Bitumen (V.F.B.)

8

7

80

6 5

70

4 60 4.5

5.0

5.5

6.0

6.5

7.0

7.5

4.5

Binder Content (pha)

5.0

5.5

6.0

6.5

7.0

7.5

Binder Content (pha)

30 Flow (0.01) 25 20

15 10 5

4.5

5.0

5.5

6.0

6.5

7.0

7.5

Binder Content (pha)

Figure 10.9.6 (10.9.8) Marshall Test Results

Max Max VIM VFB Flow Mean

CDM Stab 5% 80% II

Binder Content (p.h.a.) 6.4 6.6 6.3 7.1 6.4 6.6 p.h.a.

MAY 2001

Hence optimum binder content = 6.6 p.h.a.

Page 10.76

Chapter 10 Tests For Bitumen & Bituminous Materials 10.10

Standard Test Procedures

Bulk Specific Gravity of Compacted Bituminous Mixtures Test

10.10.1 General requirements 10.10.1.1 Scope This test provides a method of measuring the compaction of a compacted bituminous mixture in terms of its bulk specific gravity. The bulk specific gravity may be used in calculating the unit mass of the mixture. The specimen may be a laboratory moulded bituminous mixture or from bituminous pavements. The mixture may be wearing course, binder course, hot mix or levelling course. 10.10.1.2 Apparatus a) Balance, capable of weighing a sample in air and water and of ample capacity appropriate for the sample weights. The balance should be capable of weighing to an accuracy of at least 0.0001 kg. b) Water bath, for immersing the specimens in water while suspended under the balance, equipped with an overflow outlet for maintaining the water level constant. c) Thermometer, for measuring the temperature of the water in the water bath. d) A steel wire brush. e) Volumeter, calibrated to 1200 ml or appropriate capacity depending on the size of the test sample. 10.10.1.3 Preparation of specimens a) Clean the specimen well to remove any dust particles adhering to it, remove any grease, oil and other matter from it. b) Using a wire brush, scub the surface of the specimen to remove any particles that may come loose during the immersion of the specimen in water. c) The temperature of the specimen should be in close proximity to room temperature. d) Dry the specimen to a constant mass. e) If the specimen is a core consisting of more than one layer of the same material the core may be split into its different layers tested separately and averaging the result. f) If the specimen is a core consisting of more than one layer of different materials the core must be split into its different layers and each layer must be tested separately. 10.10.2 Bulk specific gravity of compacted bituminous mixtures test 10.10.2.1 a)

Methods Method A Dry the specimen to constant mass and record its dry mass A. Immerse the specimen in water at 25° C for 4 min plus or minus 1 min and record the mass, C of the specimen in water. Remove the specimen from the water, quickly damp dry the specimen by blotting with a damp cloth and determine the surface - dry mass, B of the specimen. Note.

Constant mass shall be defined as the mass at which further drying at 52°C plus or minus 3° C does not alter the mass by more than 0.05%. MAY 2001

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Standard Test Procedures

Recently moulded laboratory specimens which have not been exposed to moisture do not require drying. Samples saturated with water should be dried overnight at the specified temperature and then weighed at 2 hourly drying intervals. Note.

The sequence of the testing operations may be changed to expedite the test result. For example, first the immersed mass, C can be taken, then the surface-dry mass, B and finally the dry mass, A.

a.1) Calculations : Calculate the bulk specific gravity of the specimen as follows, round and report the value to the nearest 0.001 kg : Bulk Sp. Gr.

=

A/(B-C)

Where A = B = C =

dry mass of specimen in kg. in air. mass of surface - dry specimen in kg. in air Mass of specimen in water in kg.

Calculate the percent water absorbed by the specimen (on volume basis) as follows : Percent water absorbed b)

=

(B-A)/(B-C)

Method B Dry the specimen to constant mass and record the dry mass. Immerse in water bath and let saturate for at least 10 min. At the end of the 10 Minute period fill a calibrated volumeter with distilled water at 25° C plus or minus 1°C. Remove the immersed and saturated specimen from the water bath, quickly damp dry the specimen surface by blotting with a damp cloth and quickly as possible weigh the specimen. Place the weighed saturated specimen into volumeter and let stand for at least 60 seconds. Bring the temperature of the water in the volumeter to 25° C plus or minus 1° C, and cover the volumeter ensuring that water escapes through the overflow. Wipe the volumeter dry and weigh the volumeter and contents.

b.1) Calculations Calculate the bulk specific gravity of the specimen as follows, round and report the value to the nearest 0.001 kg. Bulk Sp. Gr. Where A = B = D = E

=

=

A/(B+D-E)

dry mass of specimen in kg. in air. mass of surface-dry specimen in kg. in air mass of volumeter filled with at 25° C plus or minus 1° C water in kg. mass of volumeter filled with the specimen and water at 25°C plus or minus 1° C, in kg.

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Standard Test Procedures

Calculate the percent water absorbed by the specimen (on volume basis) as follows : Percent water absorbed c)

=

(B-A)/(B+D-E)

Method C (Rapid test) This method can be used for specimens which are not required to be saved or which may contain large amounts of water. Specimens obtained from coring or sawing do contain water and should be tested using this method. The testing procedure shall be as given in method A or method B except the sequence of operations. The dry mass of the specimen is determined last, as follows : After the original mass in air, mass in water, and surface - dry mass have been determined, place the sample in a large flat tray and place the tray in an oven at 110° C plus minus 5° C for only long enough, for the asphalt aggregate portion of the sample to be able to be separated into fractions not greater than about 6.4 mm. Place the separated specimen into the oven again and dry to constant mass. Cool the specimen to room temperature and weight the mass A.

c.1) Calculations The calculations of method A or method B are valid for this method, Forms 10.10.1 and 10.10.2. 10.10.2.2 Expression of result Duplicate results from the same operator should be accepted if the two results do not differ by more than 0.02. 10.10.2.3 Report The test report should include at least the following information : a) b) c) d) e) f) g) h) i) j) k) l) m) n)

Name of testing agency Client name Contractor name Contract name Location sample was taken Type of sample Number of layers in sample Sample identification number Method of testing used Date sample taken Date sample tested Date sample reported Name of tester Signature of tester

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Page 10.81

Chapter 10 Tests For Bitumen & Bituminous Materials 10.11

Standard Test Procedures

Maximum Theoretical Specific Gravity of Paving

10.11.1 General requirements 10.11.1.1. Introduction 10.11.1.2

Scope

This test provides methods for calculating the specific gravity of bituminous paving mixtures when the mixtures contains no air voids. 10.11.1.3

Apparatus

a) Balance of ample capacity to provide readings for the appropriate samples of uncompacted bituminous materials and to provide sensitivity to 1.0g. For the bowl determination method the balance should be equipped with a suitable suspension apparatus and holder to permit weighing the sample while suspended from the centre of the scale pan of the balance. b) Container which shall be either a glass, metal, or plastic bowl or a volumetric flask having capacity of at least 1000ml. The container shall be sufficiently strong to withstand a partial vacuum and shall have covers as follows: (i) for use with a bowl, a cover fitted with a rubber gasket and a hose connection, (ii) for use with the flask, a rubber stopper with a hose connection. The hose opening shall be covered with a small piece of fine wire mesh to minimise the possibility of loss of fine material, The top surfaces of all containers shall be smooth and adequately plane. c) Thermometer which should be calibrated, of the liquid-in-glass total immersion type, of suitable range with graduations at least every 0.10C. d) Vacuum pump or water aspirator, for evacuating air from the container. e) Water bath, for use with the bowl, which shall be suitable for immersing in water while suspended under the balance and equipped with an overflow outlet for maintaining a constant water level. For use with the flask, a constant temperature water bath. 10.11.1.4

Calibrations

Calibrate the volumetric flask by accurately determining the mass of water 250C required to fill it. 10.11.1.5

Sample Preparation

a) Samples should obtained as per Chapter 2. b) The size of the test sample shall be governed by the nominal maximum aggregate size of the mixture and conform to the requirements of Table 10.11.1. Sample larger than the capacity of the container may be divided into smaller increments, tested and the results appropriately combined.

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Standard Test Procedures

Table 10.11.1 Nominal maximum size of aggregate mm 25.0 19.0 12.5 9.5 4.75

Minimum mass of Sample 2.5 2.0 1.5 1.0 0.5

10.11.2 Maximum theoretical specific gravity of paving mixtures; test 10.11.2.1 Procedure a) Separate the particles of the sample, taking care not to fracture the mineral particles, so that the particles of the fine aggregate portion are not larger than 6.5 mm. If the mixture is not sufficiently soft to be separated manually, place it in flat pan and warm it in an oven only until it can be so handled. b) Cool the sample to room temperature, place it in the flask or bowl, and determine its mass to the nearest 1.0g. c) After the mass determination, add sufficient water at approximately 250C to cover the sample. d) Remove entrapped air by subjecting the contents to a partial vacuum of 4.0 kPa (30 mm Hg) pressure for 15 minutes plus or minus 2 minutes. Agitate the container and contents either continuously by mechanical device or manually by vigorous shaking in a rotary motion at intervals of about 2 minutes. e) Bowl determination. Suspend the bowl and contents in water at 250C plus or minus 10C and determine its mass after 10 plus or minus 1 min. immersion. f) Flask determination. Fill the flask with water and bring the contents to a temperature of 250C plus or minus 10C in a constant-temperature water bath. Determine the mass of flask (filled) and contents 10 plus or minus 1 minutes after completing step a) of 10.11.2.1. Note.

In the absence of a constant-temperature water bath, determine the temperature of the water within the flask. Determine the mass of flask (filled) and contents 10 plus or minus 1 minutes after completing step a of 10.11.2.1. Make the appropriate density correction to 250C using the curves in Figures 10.11.1 and 10.11.2.

10.11.2.2 Calculation Calculate the maximum theoretical specific gravity of the sample as follows: 1)

Bowl determination. Specific Gravity = A / ( A – C )

(1)

Where, A is the mass of dry sample in air in grammes. C is the mass of sample in water in grammes.

2)

Flask determination MAY 2001

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Chapter 10 Tests For Bitumen & Bituminous Materials

Specific Gravity = A / ( A + D - E )

Standard Test Procedures

(2)

Where, A is the mass of dry sample in air in grammes. D is the mass of flask filled with water at 250C in grammes. E is the mass of flask filled with water and sample at 250C in grammes. 10.11.2.3 Equation for Figure 10.11.1 curves Sp. Gr. = A / (( A+F) – (G+H) x dw / 0.9970

(3)

Where, A = mass of dry sample in air in grammes F = mass of pycnometer filled with water at test temperature in grammes G = mass of pycnometer filled with water and sample at test temperature in grammes. H = correction for thermal expansion of bitumen in grammes. See Figure 10.11.2. dw = density of water at test temperature. Curve D in Figure 10.11.1, Mg/m3 0.9970 = density of water at 250C, Mg/m3 The ratio (dw / 0.09970) is curve R in Figure 10.11.1. 10.11.2.4

Reporting

The test is acceptable if two consecutive results from the same operator in the same laboratory do not differ by more than 10Kg/m3 or, if two results from different operator in a different laboratory do not differ by more than 20 kg/m3. The report example shown in Form 10.11.1 should include at least the following information: a) b) c) d) e) f) g) h) i) j)

Name of testing agency Name of client Name of contract Sample identification Sample type and number Date sample was taken Date sample was tested Name of person who tested the sample Date the result was reported Any other comments.

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Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

Figure 10.11.1 Curves D and R for Eq.3

Figure 10.11.2 Correction Curves for Thermal Expansion of Bitumen H, in Eq..3

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Chapter 10 Tests For Bitumen & Bituminous Materials

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Standard Test Procedures

Page 10.86

Chapter 11 Steel Reinforcement Tests

Standard Test Procedures

CHAPTER 11 STEEL REINFORCEMENT TESTS

11.1

General Requirements

11.1.1

Introduction Reinforcing bars are used in reinforced concrete and are one of the main parts of R.C.C. structure. For that reason, quality of plain and deformed bars should be checked specially for yield, ultimate strength and elongation (ductility). The most important test is the tensile strength test. But sometimes bending test is also done. Tension test provides information on the strength and ductility of materials under uniaxial tensile stresses. This information may be useful in comparisons of materials, alloy development, quality control and design under certain circumstances. Bend test is also a method for evaluating ductility but it cannot be considered as a quantitative means of predicting service performance in bending operations. The severity of the bend test is primarily a function of the angle of bend and inside diameter to which the specimen is bent and of the cross-section of the specimen. Plain round, hot rolled, mild steel bars are commonly used as reinforcement in concrete in Bangladesh. Reinforcing bars with various surface protrusions are also used. Reinforcing steel used in road structures must have yield and ultimate tensile strength as specified later. This chapter covers the dimensions of reinforcing bars, tensile strength and bending procedure.

11.1.2

Terminology

11.1.2.1 Definitions (1) Deformed bar. Steel bar with protrusions; a bar that is intended for use as reinforcement in reinforced concrete construction. (2) Discontinuous yielding. A hesitation or fluctuation of force observed at the onset of plastic deformation due to localized yielding. (The stress-strain curve need not appear to be discontinuous.) (3) Lower yield strength. The minimum stress recorded during discontinuous yielding, ignoring transient effects. (4) Upper yield strength. The first stress maximum (stress at first zero slope) associated with discontinuous yielding. (5) Yield point elongation. The strain (expressed in percent) separating the stressstrain curves first point of zero slope from the point of transition from discontinuous yielding to uniform strain hardening. 11.1.3

Dimensions of reinforcing bar The steel bars should be made straight and ends should be plain surface perpendicular to the longitudinal axis before measuring weight and length. Length should be sufficient (provided it does not exceed the capacity of balance) for rods of large diameter for better result. The length of the properly prepared sample to be measured in mm. The weight (W) to be taken in gm. Then the average diameter of the bar can be found as:

MAY 2001

Page 11.1

Chapter 11 Steel Reinforcement Tests

Standard Test Procedures

Average bar diameter (mm) = 12.736 x

W L

Actual diameters of many bars available in the market are less than their stated diameters. Care must therefore be exercised in procuring steel from local markets. Standard diameters and other physical properties of standard plain round bars are given in Table 11.1.1. Table 11.1.1 Dimensions of Standard Reinforcing Bars Nominal Diameter mm (in) 6 (1/4) 10

mm 6.350

(in) (0.250)

Cross Sectional Area mm2 (in2) 32.26 (0.05)

Perimeter mm 20.07

(in) (0.79)

Mass / UnitLength kg/m (1b/ft) 0.248 (0.167)

9.525

(0.375)

70.79

(0.11)

29.97

(1.18)

0.560

(0.376)

1

12.700

(0.500)

129.03

(0.20)

39.88

(1.57)

0.994

(0.668)

5

15.875

(0.625)

200.00

(0.31)

49.78

(1.96)

1.552

(1.043)

3

19.050

(0.750)

283.87

(0.44)

59.94

(2.36)

2.235

(1.502)

22

7

( /8)

22.225

(0.875)

387.10

(0.60)

69.85

(2.75)

3.042

(2.044)

25

(1)

25.400

(1.000)

509.68

(0.79)

79.76

(3.14)

3.973

(2.670)

29

1

(1 /3)

28.575

(1.128)

645.16

(1.00)

89.92

(3.54)

5.059

(3.400)

32

1

32.260

(1.270)

819.35

(1.27)

101.35

(3.99)

6.403

(4.303)

12 16 19

11.1.4

(3/8)

Actual Diameter

( /2) ( /8) ( /4)

(1 /4)

Requirements of deformed bar Deformed bars are of many sizes. From size no. 10 to size no. 55 in metric units are given in Table 11.1.2 and from size no. 3 to size no. 18 in FPS units are given in Table 11.1.3.

MAY 2001

Page 11.2

Chapter 11 Steel Reinforcement Tests Table 11.1.2

Standard Test Procedures

Deformed Bar Designation Numbers, Nominal Masses, Nominal Dimensions and Deformation Requirements as per ASTM A 615-M (Metric Units) Nominal Dimension Mass Diameter CrossSectional Area kg/m mm mm2

Deformation Requirement, mm Max. Gap Bar (chord of Designatio 12.5% of n No. Max. Av. Min. Av. Nominal Perimeter) 10 0.785 11.3 100 7.9 0.45 4.4 15 1.570 16.0 200 11.2 0.72 6.3 20 2.355 19.5 300 13.6 0.98 7.7 25 3.925 25.2 500 17.6 1.26 9.9 30 5.495 29.9 700 20.9 1.48 11.7 35 7.850 35.7 1000 25.0 1.79 14.0 45 11.775 43.7 1500 30.6 2.20 17.2 55 19.625 56.4 2500 39.4 2.55 22.2 Note. • The nominal dimensions of a deformed bar are equivalent to those of a plain round bar having the same mass per meter as the deformed bar. • Bar designation numbers approximate the number of millimetres of the nominal diameter of the bar. Table 11.1.3

Bar Designat ion No. 3 4 5 6 7 8 9 10 11 14 18 Note.

Deformed Bar Designation Numbers, Nominal Masses, Nominal Dimensions and Deformation Requirements as per ASTM A 615-M (FPS Units) Nominal Dimension Nominal Diamet CrossMass er Sectional Area 1b/ft in2 in 0.376 0.375 0.11 0.668 0.500 0.20 1.043 0.625 0.31 1.502 0.750 0.44 2.044 0.875 0.60 2.670 1.000 0.79 3.400 1.128 1.00 4.303 1.270 1.27 5.313 1.410 1.56 7.650 1.693 2.25 13.600 2.257 4.00

Deformation Requirement, mm Max. Gap (Chord Spacing Height of 12.5% of Nominal Max. Min. Av. Perimeter) Av. 0.262 0.015 0.143 0.350 0.020 0.191 0.437 0.028 0.239 0.525 0.038 0.286 0.612 0.044 0.334 0.700 0.050 0.383 0.790 0.056 0.431 0.889 0.064 0.487 0.987 0.071 0.540 1.185 0.085 0648 1.580 0.102 0864

• The nominal dimensions of a deformed bar are equivalent to those of a plain round bar having the same weight per foot as the deformed bar. • Bar numbers are based on the number of eighths of an inch included in the nominal diameter of the bar.

11.1.4.1 Requirements for deformation (1)

Deformations shall be spaced along the bar at substantially uniform distances. The deformations on opposite sides of the bar shall be similar in size and shape. MAY 2001

Page 11.3

Chapter 11 Steel Reinforcement Tests (2)

(3) (4)

(5)

Standard Test Procedures

The deformations shall be placed with respect to the axis of the bar so that the included angle is not less than 450. Where the line of deformations forms an included angle with the axis of the bar of from 450 to 700 inclusive, the deformations shall alternately reverse in direction on each side, or those on one side shall be reversed in direction from those on the opposite side. Where the line of deformation is over 700, a reversal in direction is not required. The average spacing or distance between deformations on each side of the bar shall not exceed seven tenths of the nominal diameter of the bar. The overall length of deformations shall be such that the gap between the ends of the deformations on opposite side of the bar shall not exceed 12.5% of the nominal perimeter of the bar. Where the ends terminate in a longitudinal rib, the width of the longitudinal rib shall be considered the gap. Where more than two longitudinal ribs are involved, the total width of all longitudinal ribs shall not exceed 25% of the nominal perimeter of the bar. Furthermore, the summation of gaps shall not exceed 25% of the nominal perimeter of the bar. The nominal perimeter of the bar shall be 3.14 times the nominal diameter. The spacing, height, and gap of deformations shall conform to the requirements prescribed in Table 11.1.2 and 11.1.3.

11.1.4.2 Measurement of deformations (1)

(2)

(3)

The average spacing of deformations shall be determined by dividing a measured length of the bar specimen by the number of individual deformations and fractional parts of deformations on any one side of the bar specimen. A measured length of the bar specimen shall be considered the distance from a point on a deformation to a corresponding point on any other deformation on the same side of the bar. Spacing measurements shall not be made over a bar area containing bar making symbols involving letters or numbers. The average height of deformations shall be determined from measurements made on not less than two typical deformations. Determinations shall be based on three measurements per deformation, one at the centre of the overall length and the other two at the quarter points of the overall length. Insufficient height, insufficient circumferential coverage, or excessive spacing of deformations shall not constitute cause for rejection unless it has been clearly established by determinations on each lot tested that typical deformation height, gap or spacing do not conform to the minimum requirements prescribed in Section 11.1.4.1. No rejection may be made on the basis of measurements if fewer than ten adjacent deformations on each side of the bar are measured. Note.

11.1.5

A lot is defined as all the bars of one bar number and pattern and pattern of deformation contained in an individual shipping release or shipping order.

Tensile requirements (1)

(2)

The material, as represented by the test specimens, shall conform to the requirements for tensile properties prescribed in Table 11.1.4 (metric) and in Table 11.1.5 (FPS). The percentage of elongation shall be as prescribed in Table 11.1.4

MAY 2001

Page 11.4

Chapter 11 Steel Reinforcement Tests Table 11.1.4

Standard Test Procedures

Tensile requirements as per ASTM A 615-M (Metric Units) Parameter

Tensile Strength (minimum), Mpa Yield Strength (minimum), Mpa

Requirements Grade 300 Grade 400 500 600 300

400

Elongation (minimum) in 200 mm gauge, %, for the bar size of: #10 11 #15 12 #20 #25 #30 #35 #45 #55 Note. Grade 300 bars are furnished only in sizes 10 through 20. Table 11.1.5

Tensile requirements as per ASTM A 615-M (FPS Units) Parameter

Tensile Strength (minimum), psi Yield Strength (minimum), psi

Grade 40 70,000 40,000

Requirements Grade 60 Grade 75 90,000 100,000 60,000

Elongation (minimum) in 8 inch gauge, %, for the bar size of: #3 11 9 #4, 5, 6 12 9 #7, 8 8 #9, 10 7 #11, 14, 18 7 Note. Grade 40 bars are furnished only in sizes 3 through 6. Grade 75 bars are furnished only in sizes 11, 14 and 18. 11.1.6

9 9 8 7 7 7 -

75,000

6

Bending requirements The bend-test specimen shall withstand being bent around a pin without cracking on the outside of the bent portion. The requirements for degree of bending and sizes of pins are prescribed in Table 11.1.6. (metric units) and in Table 11.1.7 (FPS units). Table 11.1.6

Bend test requirements as per ASTM A 615-M (Metric Units) Bar Size

Pin Diameter for Bend Test Grade 300 Grade 400 3.5d 3.5d 5d 5d 5d 7d 9d

#10, 15 #20 #25 #30, 35 #45, 55 (900)

MAY 2001

Page 11.5

Chapter 11 Steel Reinforcement Tests Table 11.1.7

Standard Test Procedures

Bend test requirements as per ASTM A 615-M (FPS Units) Bar Size

Note.

11.1.7

Pin Diameter for Bend Test Grade 40 Grade 60 Grade 75 #3, 4, 5 3.5d 3.5d #6 5d 5d #7, 8 5d #9, 10 7d #11 7d 7d #14, 18 (900) 9d 9d Test bends 1800 unless noted otherwise. ‘d’ is the nominal diameter of the specimen.

Permissible variation in mass The permissible variation shall not exceed 6% under nominal mass. Reinforcing bars are evaluated on the basis of nominal mass. In no case shall the overpass of any bar be the cause for rejection.

11.1.8

Finish (1) (2)

(3)

11.1.9

The bars shall be free of detrimental surface imperfections. Rust, seams, surface irregularities, or mill scale shall not be cause for rejection, provided the mass, dimensions, cross-sectional area, and tensile properties of a hand wire brushed test specimen are not less than the requirements of this specification. Surface imperfections other than those specified above shall be considered detrimental when specimens containing such imperfections fail to conform to either tensile or bending requirements.

Test specimens (a)

Tension test 1) For round reinforcing bars, full size test specimens should be used. The total length of the specimen shall be at least equal to the gauge length plus the length required for the full use of the grips employed. The test specimen must be straight. 2) Orientation of test specimen for longitudinal test : The lengthwise axis of the specimen should be parallel to the direction of the greatest extension of the steel during rolling or forging. The stress applied to a longitudinal tension test specimen is in the direction of greatest extension. The unit stress determination shall be based on the nominal bar cross-sectional area.

(b)

Bend test The bend test specimen shall be the full section of the bar as rolled.

11.1.10 Number of tests (a)

(b)

For bar size no. 10 to 35, inclusive, one tension test and one bend test shall be made of the largest size rolled from each batch. If however, material from one batch differs by three or more designation numbers, one tension and one bend test shall be made from both the highest and lowest designation number of the deformed bars rolled. For bar sizes nos. 45 and 55, one tension test and one bend test shall be made of each size rolled from each batch. MAY 2001

Page 11.6

Chapter 11 Steel Reinforcement Tests

Standard Test Procedures

11.1.11 Retest 1)

2)

3)

4) 5)

If any tensile property of any tension test specimen is less than that specified, and any part of the fracture is outside the middle third of the gage length as indicated by scribe scratches marked on the specimen before testing, a retest shall be allowed. If the results of an original tension specimen fail to meet the minimum requirements and are within 14 MPa of the required tensile strength, within 7 MPa of the required yield point, or within two percentage units of the required elongation, a retest shall be permitted on two random specimens for each original tension specimen failure from the lot. If all results of these retest specimens meet the specified requirements, the lot shall be accepted. If a bend test fails for reasons other than mechanical reasons or flaws in the specimen as described in 11.1.11(4) and 11.1.11(5) below, a retest shall be permitted on two random specimens from the same lot. If the results of both test specimens meet the specified requirements, the lot shall be accepted. The retest shall be performed on test specimens that are at air temperature, but not less than 16 0C. If any test specimen fails because of mechanical reasons such as failure of testing equipment or improper specimen preparation, it may be discarded and another specimen taken. If any test specimen develops flaws, it may be discarded and another specimen of the same size bar from the same batch substituted.

MAY 2001

Page 11.7

Chapter 10 Tests For Bitumen & Bituminous Materials 10.12

Standard Test Procedures

Spray Rate of Bitumen

10.12.1 General When carrying out surface dressing work using a motorised bitumen distributor, it is necessary to measure the rate of spread of the bitumen. Too low a rate of spray will result in chippings not adhering to the surface and too high a rate of spray will lead to ‘fatting up’ of the surface in addition to being uneconomic. There are two basic types of bitumen distributor, those which supply bitumen at a constant pressure to the spray bar and those in which the pressure on the spray bar is directly coupled to the vehicle’s engine speed. The former type is generally to the preferred as changes in the bitumen spray rate may be made simply by adjusting the speed of the vehicle, the higher the speed the lower the rate of spray. With the second type the distributor, it is only possible to change the rate of spray by engaging a different gear, the spray rate can, therefore, only be adjusted in steps, increasing the speed of the vehicle purely increases the pressure on the bar and the spray rate remains virtually constant. It should be noted that the rate of spray will be seriously affected by the grade of bitumen used and the temperature of the bitumen. The specified temperature for the particular grade of bitumen in use must be strictly maintained. The jets on the spray bar of a distributor are designed to operate at a given viscosity and, hence, harder grades of bitumen (lower penetrations) must be heated to higher temperatures than softer grades, or cut-back bitumens. Some bitumen emulsions may be sprayed without heating. The tray test is a simply field test which measures the rate of spray and allows adjustments in the speed of the vehicle (or the gears) to be made for subsequent runs. The apparatus consists simply of a number of aluminium trays, 200 mm. square and about 5 mm. deep. A balance is required for weighing the trays. Although the tray test will measure the rate of spray from a particular part of the spray bar, it cannot account for variations along the bar. It is essential that all the jets are fully cleaned and operating freely and that the bar is level and at the correct height. 10.12.2 Test Procedure The clean dry trays are numbered on the underside and weighted. Usually 5 trays are used for each test and to allow time for cleaning at least 10, and preferably 15 trays, are required for quality control work. The trays are then placed on the prepared road surface in a random pattern in front of the distributor lorry. The trays should be spaced out along the whole length to be sprayed and should cover the full width of the spray bar, excepting the very edges where there is no overlap on the jets. Obviously the trays must not be placed in the path of the distributor wheels, as the distributor is normally only moving at walking pace the position of the trays may be adjusted as the lorry approaches. Immediately after spraying the trays should be carefully lifted from the surface with a pair of tongs or pliers and re-weighed. To enable the trays to be removed, it is usually necessary to spread a few chippings on to the surface of the bitumen to allow the operative to reach the tray without

MAY 2001

Page 10.87

Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures

damaging the surface. Immediately after removing the tray, the area of road under the tray should be covered in not bitumen from a bitumen pouring can. After use, the trays should be thoroughly cleaned, using a solvent such as diesel, kerosine or petrol, this operation should be carried out in an open space away from fires or other sources of heat. Any damaged trays should be repaired and checked for dimensional accuracy. The trays should be re-weighed each time, before use. If it is required to measure the rate of spread of chippings laid on the bitumen, the same procedure may be used but larger sized trays will give more accurate results. A few chippings should be spread in the bitumen under the trays to prevent the bitumen contaminating the underside of the trays. 10.12.3 Calculation Weight of bitumen in tray, W = (Weight of tray + Bitumen) – (Weight of tray) grams

Area of tray ,A

Lenght breadth x sq. meter 1000 1000

Where length and breadth are in millimetres Spray rate

=

W grams / sq . metre A

W W Kg / sq . metre = 1000 A 1000 A b

litres / sq . metre

Where b is density of bitumen at road temperature (Normally taken as 1.0) Typical results are shown as Form 10.12.1. 10.12.4

Reporting of Results The individual results should be reported to the nearest 0.1 kg/sq.metre. The speed of the distributor, the grade of bitumen, the temperature of spraying and the detailed position of the test should be given.

MAY 2001

Page 10.88

Chapter 10 Tests For Bitumen & Bituminous Materials

Standard Test Procedures Form 10.12.1

MAY 2001

Page 10.89

Chapter 11 Steel Reinforcement Tests

Standard Test Procedures

11.2

Tension Test of Steel Reinforcing Bar

11.2.1

Scope The tension test relates to the mechanical testing of steel products subjects a machined or full-section specimen of the material under examination to a measured load sufficient to cause rupture. These test methods cover the tension testing of metallic materials in any form at room temperature, specifically, the methods of determination of yield strength, yield point elongation and tensile strength. Room temperature shall be considered to be 10 0C to 38 0C unless otherwise specified.

Note.

11.2.2

Apparatus a)

Testing machine : Universal compression / tension machine motorised. Capacity minimum 100-kN for compression and 500 kN for tension, 220-240V, 50 Hz, 1 phase. Suitable for tension testing of reinforcing base up to 25 mm diameter. All accessories for tension testing including universal grip holders to be included during procurement of the machine.

b)

Gripping devices General : Various types of gripping devices may be used to transmit the measured load applied by the testing machine to the test specimens. To ensure axial tensile stress within the gauge length, the axis of the test specimen should coincide with the centre line of the heads of the testing machine. Loading : It is the function of the gripping or holding device of the testing machine to transmit the load from the heads of the machine to the specimen under test. The essential requirement is that the load shall be transmitted axially. This implies that the centres of the action of the grips shall be in alignment, in so far as practicable, with the axis of the specimen at the beginning and during the test, and that bending or twisting be held to a minimum. Gripping of the specimen shall be restricted to the section outside the gauge length. Wedge Grips : Testing machines usually are equipped with wedge grips. These wedge grips generally furnish a satisfactory means of gripping long specimens of ductile metal. For proper gripping, it is desirable that the entire length of the serrated face of each wedge be in contact with the specimen.

c)

Other Apparatus i) ii)

iii) iv)

Double Pointed Centre Punch or Scribe Marks: For marking of round specimen. Special Scale : For direct reading of % elongation (for particular gauge length) special pointed scale may be used. Minimum division of 0.5% is sufficient for this purpose. Extensometer : Extensometer with gauge length equal to or shorter than the nominal gauge length of the specimen is used to determine the yield phenomenon. Slide calipers.

MAY 2001

Page 11.8

Chapter 11 Steel Reinforcement Tests 11.2.3

Standard Test Procedures

Speed of testing 1)

2)

Rate of straining : The allowable limits for rate of straining shall be specified in meters per meter per second. Some testing machines are equipped with pacing or indicating devices for the measurement and control of rate of straining, but in the absence of such a device the average rate of straining can be determined with a timing device by observing the time required to effect a known increment of strain. Rate of stressing : The allowable limits for rate of stressing shall be specified in MPa per second. Many testing machines are equipped with pacing or indicating devices for the measurement and control of the rate of stressing, but in the absence of such a device the average rate of stressing shall be determined with a timing device by observing the time required to apply a known increment of stress. Note.

3)

4)

Speed of testing can affect test values because of the rate sensitivity of materials and the temperature-time effects.

Elapsed time : The allowable limits for the elapsed time from the beginning of force application (or from some specified stress) to the instant of fracture, to the maximum force, or to some other stated stress, shall be specified in minutes or seconds. The elapsed time can be determined with timing device. When determining yield properties : Unless otherwise specified, any convenient speed of testing may be used up to one half the specified yield strength or yield point, or up to one quarter the specified tensile or ultimate strength, whichever is smaller. The speed above this point shall be within the limits specified. If different speed limitations are required for use in determining yield strength, yield point, tensile strength, elongation, and reduction of cross-sectional area they should be stated in the product specifications. In the absence of any specified limitations on speed of testing the following general rules apply. a) The speed of testing shall be such that the loads and strains used in obtaining the test results are accurately indicated. b) During the conduct of the test to determine yield strength or yield point, the rate of stress application shall not exceed 12 MPa/sec.

5)

11.2.4

When determining tensile strength : After the yield strength point has been determined, the speed may be increased to correspond to a maximum strain rate of 0.01 m/m/s. The extensometer and strain rate indicator may be used to set the strain rate prior to its removal. If the extensometer and strain rate indicator are not used to set this strain rate, the speed should be set not to exceed 0.01 m/m of the length of the reduced section (or distance between the grips for specimens not having reduced sections) per second.

Gauge length, marking. The gauge should be five times the diameter (unless otherwise specified). Round specimens are gauge marked with a double pointed centre punch or scribe marks. The gauge points shall be approximately equidistant from the centre of the length of section.

MAY 2001

Page 11.9

Chapter 11 Steel Reinforcement Tests

Standard Test Procedures

L

B

A

B

W

L = Overall length A = Length of reduced section B = Length of grip section C = Dia of grip section W = Dia of reduced section G = Gauge length R = Radius of fillet

C

R G

Figure 11.1.1 Tension test specimen

11.2.5

Test procedure a) b) c) d) e)

Measure the diameter of the specimen by the weight method described in section 11.1.3 or by slide calipers. Record extensometer constant and gage length. Fix the specimen at the centre of the properly placed grip of the machine. Fix the extensometer with the specimen. After completion of all arrangements as per requirement (described earlier) and setting the speed of machine, etc. switch the machine on. Load is increased gradually until the specimen fails by tensile force. Note. If any test specimen fails because of mechanical reasons such as failure of testing equipment or improper specimen preparation, it may be discarded and another specimen taken.

f)

11.2.6

Then determine the yield and ultimate strength and elongation etc. Methods of determination of these tensile properties are described in section 11.2.6.

Determination of tensile properties

11.2.6.1 Yield Point : Yield point is the first stress in a material, less than the maximum obtainable stress, at which an increase in strain occurs without an increase in stress as shown in Figure 11.2.2. Yield point is intended for application only for materials that may exhibit the unique characteristic of showing an increase in strain without an increase in stress. For this type of material, the stress-strain diagram is characterised by a sharp knee or discontinuity. Yield point can be determined as described below. a)

‘Drop of the Beam’ or ‘Halt of the Pointer Method (method commonly used): In this method apply an increasing load to the specimen at a uniform rate. When a lever and poise machine is used, keep the beam in balance by running out the poise at approximately steady rate. When the yield point of the material is reached, the increase of the load will stop. However, run the poise a trifle beyond the balance position, and the beam of the machine will drop for a brief but at appreciable interval of time. When a machine equipped with a load-indicating dial MAY 2001

Page 11.10

Chapter 11 Steel Reinforcement Tests

Standard Test Procedures

is used, there is a halt or hesitation of the load-indicating pointer corresponding to the drop of the beam. Note the load at the “drop of the beam” or the “half of the pointer” and record the corresponding stress as the yield point. b)

Autographic Diagram Method (alternative to 11.2.6.1(a) if such device is available): When a sharp-kneed stress-strain diagram is obtained by an autographic recording device, take the stress corresponding to the top of the knee, or the stress at which the curve drops as the yield point.

11.2.6.2 Yield Strength : Yield strength is the stress at which a material exhibits a specified limiting deviation from the proportionality of stress to strain. This is shown in Figure 11.2.2. In a simplified way the stress corresponding to the yield-point may be taken as the ‘Yield-Strength’. In the ‘Halt of the Pointer’ method or when the stress-stress diagram is not available, the ‘Yield-Strength’ is calculated by dividing the load at yieldpoint by the original cross-sectional area. 11.2.6.3 Tensile/Ultimate Strength : The stress corresponding to the maximum point of the stress-train diagram is the ‘Tensile Strength’ or ‘Ultimate Strength’. This is shown in Figure 11.2.2. When the stress-strain diagram is not available; calculate the ‘Tensile Strength’ or ‘Ultimate Strength’ by dividing the maximum load the specimen sustains during a tension test by the original cross-sectional area of the specimen.

TENSILE / ULTIMATE STRENGTH

YIELD-STRENGTH (In a simplified way)

Stress

Yield-point

Strain

Figure 11.2.2 Yield and Ultimate Strength in the Stress-Strain Diagram in an Autographic Recording Device

11.2.6.4 Elongation a)

b)

Fit the ends of the fractured specimen carefully and measure the distance between the gauge marks to nearest 0.25 mm (0.01 in.) for gauge lengths of 50 mm and under, and to the nearest 0.5 percent of the gage length for lengths over 50 mm. A percentage scale reading to 0.5 percent of the gauge length may be used. The elongation is the increase in length of the gauge length, expressed as a percentage of the original gage length. In reporting elongation values, give both the percentage increase and the original gauge length. If any part of the fracture takes place outside of the middle half of the gage length, the elongation value obtained may not be representative of the material. If MAY 2001

Page 11.11

Chapter 11 Steel Reinforcement Tests

Standard Test Procedures

the elongation so measured meets the minimum requirements specified, no further testing is indicated, but if the elongation is less than the minimum requirements, discard the test and retest. 11.2.7

Rounding of test data In the absence of a specified procedure for rounding the test data, it is recommended to use the Table 11.2.1 for rounding the test result. Table 11.2.1 Recommended Values for Rounding Test Data Parameter

Range 0 to <500 MPa

Rounded Vale 1 MPa

500 to <1000 MPa

5 MPa

≥ 1000 MPa

10 MPa

0 to <10%

0.5 %

≥ 10 %

1%

Yield/Ultimate Strength

Elongation

Note.

11.2.8

Round test data to the nearest integral multiple of the values in this table. If the data value is exactly midway between two rounded values, round to the higher value.

Replacement of specimens A test specimen may be discarded and a replacement specimen selected from the same lot of material in the following cases: a) b) c) d) e) f)

the original specimen had a poor surface the original specimen had the wrong dimensions the test procedure was incorrect the fracture was outside the gage length for elongation determinations, the fracture was outside the middle half of the gage length, or there was a malfunction of the testing equipment

An example data sheet is given as Form 11.2.1. 11.2.9

Report Test information to be reported shall include the following when applicable: 1) 2) 3) 4) 5)

Material and sample identification Yield strength Yield point Tensile strength Elongation (report both the original gage length and the percentage increase).

MAY 2001

Page 11.12

Chapter 11 Steel Reinforcement Tests

Standard Test Procedures

MAY 2001

Page 11.13

Chapter 11 Steel Reinforcement Tests 11.3

Standard Test Procedures

Bend Test of Reinforcing Bar

11.3.1

Scope. This test method is used for evaluating ductility. Unless otherwise specified it shall be permissible to age bend test specimen. The time-temperature cycle employed must be such that the effects of previous processing will not be materially changed. It may be accomplished by aging at room temperature 24 to 48h or in shorter time at moderately elevated temperatures by boiling in water, heating in oil or in an oven.

11.3.2

Test method. Bend the test specimen at room temperature to an inside diameter, as designated by the applicable product specifications, to the extent specified with major cracking on the outside of the bent portion.

11.3.2.1 (1) Procedure. The bend test shall be made on specimens of sufficient length to ensure free bending and with apparatus which provides: a) b) c)

Continuous and uniform application for force throughout the duration of the bending operation. Unrestricted movement of the specimen at points of contact with the apparatus and bending around a pin free to rotate. Close wrapping of the specimen around the pin during the bending operation.

(2)

Other acceptable, more severe methods of bend testing, such as placing a specimen across two pins free to rotate and applying the bending force with a fixed pin, may be used. When failures occur under more severe methods, retest shall be permitted under the bend test method prescribed in 11.3.2.1(1) above.

(3)

A field bend test may be done which is similar to 11.3.2.1(2) above. This is also an acceptable method. The sample is placed between two or three fixed pins in such a way that it is free to rotate. Then bending force is applied uniformity. If the sample specimen withstands this force without cracking on the outside of the bent portion, then it is considered to be acceptable in respect of bending. Note.

(4)

When re-testing is permitted by the product specification, the following shall apply: a) b)

11.3.3

Sometimes in the work site the bending of reinforcement (plain bar) is done with beating. This should be strictly prohibited.

Sections of bar containing identifying roll marking shall not be used. Bar shall be so placed that longitudinal ribs lie in a plane at right angles to the plane of bending.

Report If the bending around the pin could be done without cracking on the outside of the bent portion the result is ‘satisfactory’. If cracking was found on the outside of the bent portion, it would be considered that the rod did not meet the bending requirements and the result is ‘unsatisfactory’. An example data sheet is given as Form 11.3.1.

MAY 2001

Page 11.14

Chapter 11 Steel Reinforcement Tests

Standard Test Procedures

MAY 2001

Page 11.15

Form 2.2.1 BANGLADESH ROAD RESEARCH LABORATORY

SAMPLE RECORD CARD

Contract : Sample no. Origin of sample : Date of sampling Borehole / Trial pit no. : Depth of sample :

From To

Description of soil :

Moisture content container nos. : Adjacent in-situ test / undisturbed sample :

Type of test

Position / depth of test

Special Instructions / Remarks : Name and Designation of Sampler :

Sheet no.

Result

m m

Form 2.3.1 SAMPLING CERTIFICATE OF BRICKS

Name of testing agent

Manufacturer

Sample number

Client

Consignment

Number of bricks in sample

Name and designation of sampler

Contractor's name

Contract

Batch number / lot no.

Date of manufacture

Date of sampling

Number of bricks in lot.

Testes required

Date delivered

Date tested

Signature

Form 2.4.1 SAMPLING CERTIFICATE OF AGGREGATES

Name of testing agent

Manufacturer

Sample number

Client

Description of material

Number of samples

Name and designation of sampler

Contractor's name

Contract

Date of sampling

Identification number

Location material was sampled

Tests required

Any other information

Date tested

Signature

Form 2.6.1 CERTIFICATE OF SAMPLING : CEMENT / FRESH CONCRETE

Testing agency

Client

Contract name

Location in structure

Sample number

Batch number

Temperature of concrete

Ambient temperature

Name and designation of sampler

Date of sampling

Concrete grade

Signature

Tests required :

Any other comments :

Form 3.1.1 BANGLADESH ROAD RESEARCH LABORATORY

MOISTURE CONTENT DETERMINATION

Contract :

Sample No. Date of sampling

Description of soil :

Type / origin of sample :

Method of drying : Oven / Sand bath 0 Drying temp. C

Container No. Position of sample Mass of wet soil + container (m 2)

g

Mass of dry soil + container (m 3)

g

Mass of moisture (m 4 = m 2 - m 3)

g

Mass of container (m 1)

g

Mass of dry soil (m 5 = m 3 - m 1)

g

Moisture content

m w = 4 x 100 % m5

Average moisture content

%

Date of test :

Operator

Contract :

Name and Designation Checked

Approved

Sample No. Date of sample

Description of soil :

Type / origin of sample :

Method of drying : Oven / Sand bath 0 Drying temp. C

Container No. Position of sample Mass of wet soil + container (m 2)

g

Mass of dry soil + container (m 3)

g

Mass of moisture (m 4 = m 2 - m 3)

g

Mass of container (m 1)

g

Mass of dry soil (m 5 = m 3 - m 1)

g

Moisture content

w =

Average moisture content

Date of test :

m4 x 100 % m5 %

Operator

Name and Designation Checked

Approved

Form 3.2.1 BANGLADESH ROAD RESEARCH LABORATORY

ATTERBERG LIMITS TEST (Cone penetrometer method)

Contract

Sample No. ___________

Origin of sample

Date of Sample ________ Description of soil Date of Test:

Test

Plastic Limit 1

Liquid Limit 2 3

Container No.

4

Sample preparation *

Mass of cont. + wet soil

g

Mass of cont. + dry soil

g

Mass of moisture

g

Mass of container

g

as received washed on 425 mm sieve o air dried at ................ C o oven dried at ............. C not known

Mass of dry soil

g

* Delete as appropriate

Moisture content

%

Average

%

282

Cone Penetration mm

262 2424 22 22 2 20 0 1 18 8 1 16 6

141 4 12 12

Moisture Content % Liquid Limit

Test No. Final dial gauge

1 mm

Summary

2

3

4 % of total sample passing

reading

425mm sieve

%

Initial dial gauge

Liquid limit (LL)

%

Plastic limit (PL)

%

Plasticity Index (PI)

%

mm

reading Average

mm

penetration Name and Designation Operator Checked Approved Remarks

Form 3.2.1

BANGLADESH ROAD RESEARCH LABORATORY

ATTERBERG LIMITS TEST (Casagrande Method)

Contract Sample No._____________

Origin of sample

Date of sample _________ Description of soil Date of Test:_____________

Test Container No.

Plastic Limit

Liquid Limit

No. of Blows g g

Wt. of moisture

g

Wt. of container

g

Wt. of dry soil

g

Moisture content

%

Average

%

Moisture Content %

Wt. of cont. + wet soil Wt. of cont. + dry soil

10

15

20

25

30

40

35

45

50

Number of Blows Sample preparation * as received washed on 425 mm sieve air dried at _______ 0C oven dried at _______ oC not known * Delete as appropriate

Summary % of total sample passing 425mm Sieve

%

Liquid Limit (LL)

%

Plastic Limit (PL)

%

Plasticity Index (PI)

%

Linear Shrinkage (LS)

%

If LL or PL cannot be determined use PI = 2.13 x LS Remarks ______________________________________ ______________________________________ ______________________________________

=

%

Name and Designation Operator

Checked

Approved

Form 3.3.1 BANGLADESH ROAD RESEARCH LABORATORY

PARTICLE SIZE DISTRIBUTION STANDARD WET SIEVING METHOD

Contract :

Sample No.

Origin of sample :

Date of Sample

Description of soil :

m1

Initial dry mass

g

SIEVE SIZE

Passing

Mass retained g actual corrected m

m2 = m3

14 mm 10 mm 6.3 mm 5 mm 5 mm total riffled

Correction factor

Passing Total Remarks :

 m    100  m1 

Cumulative percentage passing

75 mm 63 mm 50 mm 37.5 mm 28 mm 20 mm m2 20 mm total (check with m1) riffled m3 riffled and washed m4

Correction factor

Passing

Percentage retained

=

m5 (check with m4) m6

m2 m x 5 = m3 m6

3.35 mm 2 mm 1.18 mm 600 µm 425 µm 300 µm 212 µm 150 µm 75 µm 75 µm (check with m6)

=

ME (m1)

Name and Designation Operator Checked Approved Date of test :

Form 3.3.2 BANGLADESH ROAD RESEARCH LABORATORY

PARTICLE SIZE DISTRIBUTION DRY SIEVING METHOD

Contract :

Sample No.

Origin of sample :

Date of Sample

Description of soil :

m1

Initial dry mass

g

SIEVE SIZE

Passing

Mass retained g actual corrected m

75 mm 63 mm 50 mm 37.5 mm 28 mm 20 mm 20 mm total riffled

Passing

14 mm 10 mm 6.3 mm 5 mm 5 mm total riffled

Correction factor

Passing Total Remarks :

 m    100  m1 

Cumulative percentage passing

m2 (check with m1) m3

m2 = m3

Correction factor

Percentage retained

=

m4 (check with m3) m5

m2 m x 4 = m3 m5

3.35 mm 2 mm 1.18 mm 600 µm 425 µm 300 µm 212 µm 150 µm 75 µm 75 µm (check with m5)

=

ME (m1)

Name and Designation Operator Checked Approved Date of test :

Form 3.3.2 BANGLADESH ROAD RESEARCH LABORATORY

PARTICLE SIZE DISTRIBUTION DRY SIEVING METHOD

Contract :

Sample No.

Origin of sample :

Date of Sample

Description of soil :

m1

Initial dry mass

g

SIEVE SIZE

Passing

Mass retained g actual corrected m

75 mm 63 mm 50 mm 37.5 mm 28 mm 20 mm 20 mm total riffled

Passing

14 mm 10 mm 6.3 mm 5 mm 5 mm total riffled

Correction factor

Passing Total Remarks :

 m    100  m1 

Cumulative percentage passing

m2 (check with m1) m3

m2 = m3

Correction factor

Percentage retained

=

m4 (check with m3) m5

m2 m x 4 = m3 m5

3.35 mm 2 mm 1.18 mm 600 µm 425 µm 300 µm 212 µm 150 µm 75 µm 75 µm (check with m5)

=

ME (m1)

Name and Designation Operator Checked Approved Date of test :

Form 3.3.3 BANGLADESH ROAD RESEARCH LABORATORY

PARTICLE SIZE DISTRIBUTION CHART

Contract

Job ref. no

Sample No.

Origin of sample :

Date of Sample

Description of soil : APERTURE SIZE IN INCHES

150

100

72

52

36

25

18

75

105

150

210

300

425

600

850

14

10

7

1.18 1.70

2.36

1/8"

1

1

3/16"

1/4"

3/8"

1/2"

3/4"

1"

1 /2"

2"

2 /2"

4.75

6.30

9.50

12.50

19.00

25.00

37.50

50.00

63.00

3.15

3"

4"

75.00 100.00

MILLIMETRES

100

0

90

10

80

20

70

30

60

40

50

50

40

60

30

70

20

80

10

90

0

100 0.06

0.2

FINE

Remarks :

0.6

MEDIUM SAND

6

2

COARSE

FINE

20

MEDIUM GRAVEL

60

COARSE

PERCENTAGE RETAINED

PERCENTAGE PASSING

BS SIEVE NUMBERS 200

100 MM

COBBLES

Name and Designation Operator Checked Approved

Form 3.5.1 BANGLADESH ROAD RESEARCH LABORATORY

SOILS DESCRIPTION COARSE SOILS

Contact :

Sample No.

Origin of sample :

Date of Sample

Date of Test : Component 1

MOISTURE

STP Reference Section 3.5.4.2(1)

CONDITION

2

CONSISTENCY

Description * Dry Moist

Slightly moist Very moist

Wet

Table 3.5.1 Table 3.5.2

3

COLOUR

Section 3.5.4.2(3)

4

STRUCTURE

Table 3.5.6

Very loose

Loose

Medium dense

Dense

Very dense

Sl. Cemented

Sand

Gravel

Cobbles

Boulders

Table 3.5.7

5

SOIL TYPE

Table 3.5.12 Table 3.5.14 Table 3.5.15 Figure 3.5.1 Table 3.5.11

6

ORIGIN

Section 3.5.4.2(6)

Remarks :

FULL DESCRIPTION

Note : * Circle as appropriate

Name and Designation of Operator

Form 3.5.2 BANGLADESH ROAD RESEARCH LABORATORY

SOILS DESCRIPTION FINE SOILS

Contact :

Sample No.

Origin of sample :

Date of Sample

Date of Test : Component 1

MOISTURE

STP Reference Section 3.5.4.2(1)

CONDITION

2

CONSISTENCY

Description * Dry

Slightly moist

Moist

Table 3.5.3

Very moist

Very soft Firm

3

COLOUR

Section 3.5.4.2(3)

4

STRUCTURE

Table 3.5.7

Soft Stiff

Very stiff / hard

Table 3.5.4 Table 3.5.5

Wet

Firm

Spongy

Plastic

SILT

CLAY

PEAT

Table 3.5.8 Table 3.5.9 Table 3.5.10

5

SOIL TYPE

Table 3.5.13 Table 3.5.11

6

ORIGIN

Section 3.5.4.2(6)

Remarks :

FULL DESCRIPTION

Note : * Circle as appropriate

Name and Designation of Operator Operator