Te U-6 - Copy.pdf

Highway construction

Types of highway constructions

Earth road and gravel roads Water bound macadam roads(WBM) Cement concrete roads

Soil survey ◗ The objective of soil survey is to determine the soil types occurring along alignment and to locate the sources of borrow soil for embankments ◗ Soil sampling at an interval of 200 m ◗ Soil samples to be evaluated for different geotechnical properties

Earthwork for embankment/subgrade (As per specifications) • Suitability of materials – Free from peat, perishable and other organic material – Should not be spontaneously combustible – LL should be less than 70, PI should be less than 45 – Soils having salts are not suitable – Free Swell Index more than 50 % should not be used

Earthwork for embankment/subgrade (contd.) • Spreading of material in layers and bringing to appropriate moisture content.  Maximum compacted layer thickness should not exceed 200 mm  Moisture content between OMC - 2 % to OMC + 1%  Expansive soils to be compacted at OMC or on wet side of optimum

Preparation of sub grade •The preparation of sub grade includes all operations before the pavement structure could be laid over it and compacted •Sub grade would include site clearance , grading (embankment or cut section) and compaction

Objectives of soil compaction • Increase in strength • Reduction in compressibility • Reduction in tendency for subsequent changes in moisture content • Reduction in erodability • Reduction in frost susceptibility

Machinery for earthwork -Dozers

JCB

(Backhoe cum Loader)

Motor grader

Tractor as grader

Tractor as plough

Vibratory roller

Tandem vibratory roller

Static roller

Small vibratory roller

Plate compact or

Compacted subgrade

Field control of compaction • Measurement of dry density – Core cutter method (IS: 2720 (Part 29) - 1975)

– Sand replacement method (IS: 2720 (Part 28) - 1974)

– Nuclear density & moisture gauge (ASTM D- 2922)

Field control of compaction (contd.) • Measurement of moisture content – Pan drying method

– Speedy moisture meter (IS 2720 (Part 2 - 1973)

– Microwave oven method (ASTM D: 4643-1989)

High embankment • Failures within the body of embankment  Incorrect design practices  Poor quality fill materials  Improper construction methods  Lack of quality control • Failures involving foundation  Inadequate subsoil investigation • Design of high embankment  Using MoRTH or any other suitable software  Target FS = 1.25 for economical design

Earthwork under special conditions

•

Earthwork over existing road surface

•

Embankment construction in waterlogged areas

•

Construction of embankment over soft soils

•

Inadequate compaction of backfill material in trenches dug for services in urban areas

•

Low cost roads may cater for 30 t to 200 t per day

Compaction of ground with underlying cables, water pipelines, sewer lines, etc.

Settlement of pavement due to improper compaction of backfill material in the trenches

Effect of earthquake on embankment

Shallow cracks in road pavement

Deep and wide cracks in embankment

• Depth of crack upto 1m • width of crack 10 cm- 80 cm

Failures on the side slopes

Sinking of side slopes

Severe damage to stone- pitching on embankment slopes

Major slides/ subsidence

Erosion control of slopes  Common methods  Simple vegetative turfing  Transplantation of ready made turf of grass  Straw with cowdung or wood shavings or sawdust as mulch  Special techniques  Asphalt mulch technique  Use of jute/ coir netting

Erosion Control of Slopes

Use of jute geotextile for erosion control

Stone pitching for slope protection

Construction of gravel roads Gravel roads are considered superior to earth roads as they can carry heavier traffic Camber may be between 1in 25 and 1 in 30 This type of roads can cater for about 100 t of pneumatic tyred vehicles or 60 t of iron tyred vehicles per day per lane Hard variety of crushed stones or gravel of specified gradation is used Rounded stones and river gravel are not preferable

Preparation of sub grade and cuts are completed

:

site is cleared and fills

Pavement construction : place the crushed gravel aggregates carefully So that we can avoid seggregation Aggregates are spread with greater thickness at center and less towards the edge so as to obtain the desired camber

Opening to traffic

Sub-base course • Intermediate layer between sub grade and granular base course • Essentially a drainage layer • Distributes the stresses imposed by traffic

Materials for sub base • Locally available materials (no specifications for materials)  Natural sand  Gravel or moorum  Kankar  Crushed stone  Laterite  Rounded and river gravel are not preferable • Industrial waste and other materials  Steel slag  Pond ash or Pond-Bottom ash mix  Crushed concrete  Brick bats

Spreading of pond ash

Second Nizamuddin bridge approach embankment

Compaction of pond ash

Construction operations - GSB • Preparation of subgrade • Mixing and preparation of GSB

• Spreading and compacting Moisture content to be between OMC+1% to OMC - 2% Use of static roller (8 to 10ton) for compacted layer thickness less than 100 mm Use of vibratory roller for compacted layer thickness upto 225 mm • Rolling Starting from edges going towards center Speed of roller not to exceed 5 km/h

Water Bound Macadam • Materials  Aggregates  Screening  Binding material • Aggregates  Crushed or broken stone  Crushed slag  Overburnt brick aggregates for sub-base

Water Bound Macadam • Aspects to be considered – Grading of aggregates – Strength of aggregates – Shape of aggregates – Water absorption – Screening material – Binding material

Gradation of aggregates for WBM

Water Bound Macadam Physical requirements of aggregates for WBM / WMM / CRM (MORTH)

Physical requirements of aggregates for WBM (Rural Roads Manual)

Water Bound Macadam Quality control tests for WBM (MORTH & Rural roads Manual) Sl.No. 1.

2.

3.

4

5

Test

Relevant code

Frequency of test

Aggregate impact value or Los Angeles abrasion value

IS:2386 : Part - 4

1 test / 200 m3

Aggregate gradation

IS:2386 : Part - 1

Combined Flakiness and Elongation index

IS:2386 : Part - 1

Atterberg limits of binding material

IS:2720 : Part - 5

Atterberg limits of aggregates finer than 425 micron

IS:2720 : Part - 5

1 test / 250 m3 (Only AIV – Rural Roads Manual) 1 test / 100 m3 1 test / 125 m3 (Rural Roads ) 1 test / 200 m3 1 test / 250 m3 (Only FI – Rural Roads Manual) 1 test / 25 m3 1 test / 50 m3 (Rural Roads ) 1 test / 100 m3

Water Bound Macadam Gradation of screenings

Water Bound Macadam Quantity of materials

WBM as wearing course • Only WBM Grade III can be adopted as wearing course as per Rural Roads Manual Plasticity requirements of binding material for wearing course

WBM - Construction • Preparation of sub base to specified crossfall • Spreading of coarse aggregates • Rolling • Application of screenings • Watering and brooming • Application of binding material • Watering and rolling • Setting and drying

WBM Construction

Stone metal for WBM

Spreading of stone metal

Spreading of screening

WBM Construction

Applying binder for WBM

Watering & rolling of WBM

Difficulty due to soft subgrade

Close-up View of WBM

CONSTRUCTION OF BITUMINOUS PAVEMENTS

Types of Bituminous Layers

Bituminous construction are classified into four categories

 Interface Treatments  Thin Bituminous Surfacing  Bituminous Surface Courses  Bituminous Binder Courses

INTERFACE TREATMENTS

 Prime Coat  Tack Coat

Prime coat Application of single coat of low viscosity liquid bituminous material to a porous granular surface choice of a bituminous primer - depend upon the porosity characteristics of the surface to be primed as classified in IRC : 16. (i) Surfaces of low porosity; such as wet mix macadam & water bound macadam,, (ii) Surfaces of medium porosity; such as cement stabilized soil base, (iii)Surfaces of high porosity; such as a gravel base .

PURPOSE OF PRIMING 

To plug the capillary voids



To coat and bond loose materials on the surface



To harden or toughen the surface



To promote adhesion between granular and the bituminous layer

REQUIREMENT FOR PRIMING MATERIAL Porosity

Type of Surface

Viscosity at Quantity 600 C per 10 m2 (Kg) (centistokes)

Low

WMM, WBM

30-60

7-12

Medium

Gravel base

70-140

9-12

Stabilised base

250-500

12-15

High

Prime coat- Slow setting Cationic emulsion as per IS : 8887-2004 Mechanical sprayer at rate of 7.3 to 14.6 kg per 10 m2 area

Prime Coat

Prime coat Weather and Seasonal Limitations - primer shall not be applied on a wet surface or during dust storm or when the weather is foggy, rainy or windy. -should not be applied when the temperature in the shade is less than 10oC

Construction  Equipment:

-pneumatic tyred self-propelled pressure distributor equipped for spraying the material uniformly at the specified rates and temperatures Preparation of road surface: -swept clean, free from dust and shall be dry . -shaped to the specified grades and section. -free from ruts, any other irregularities and segregated materials. Minor depressions and potholes may be ignored until the surface is primed, after which they shall be patched with a suitable premix material prior to the surface treatment.

Application of bituminous primer: -shall be sprayed/distributed uniformly over the dry surface, prepared using self-propelled sprayer equipped with self-heating arrangement, suitable pump, adequate capacity compressor and spraying bar with nozzles having constant volume or pressure system capable of supplying primer at specified rates and temperatures so as to provide a uniformly unbroken spread of primer. Surface- dry or dusty as to cause freckling of bituminous material, sprinkled with water immediately prior to priming; however, the bituminous material shall not be applied till such time as no surface water is visible.

Curing of primer and opening to traffic: Fully cured and is not sticky to avoid being picked up by traffic. - allowed to cure for not less than 24 hours and during this period no traffic of any kind shall be not permitted . - measured in terms of surface area of application in square metres.

TACK COAT Purpose of Tack Coat: 

To ensure a bond between the new construction and the old surface

Use of Cutback: exceptional cases 

It should be restricted for sites at subzero temperatures or for emergency applications

Weather and Seasonal Limitations shall not be applied on a wet surface or during dust storm or when the weather is foggy, rainy or windy.  -

Construction Operation Equipment- self propelled/towed bitumen pressure sprayer equipped for spraying the bitumen uniformly- inaccessible- Hand sprayers Preparation of base: -cleaned of dust and any extraneous material before the application of the binder, by using a mechanical broom or any other approved equipment/method as specified by the Engineer Application – Rate specified in the contract , unformly to be applied

Surface Cleaning

TABLE 500-2. RATE OF APPLICATION OF TACK COAT Type Surface

Quantity of liquid Bituminous material in kg per sq. m. area

i)

Normal bituminous surfaces

0.2 to 0.25

ii)

Dry and hungry bituminous surfaces

0.25 to 0.30

iii)

Granular surfaces treated with primer

iv)

Non bituminous surfaces a)Granular base (not primed) b)Cement concrete pavement

1.0.25 to 0.30 0.35 to 0.40 0.3 to 0.35

-range of spraying temperature 20

0

C - 60

0

C;

-cutback 50 0 C – 80 0C if RC-70/MC-70 grade is used.

WRONG PRACTICE OF TACK COAT

MECHANICAL SPRAYER FOR TACK COAT Tack coat is usually applied by spraying bituminous material of higher viscosity like the hot bitumen at the rate of 4.9 to 9.8 kg per 10 m2 area

INSUFFICIENT TACK COAT

Apply Tack Coat Typical Application

Does this look okay?

Tack Coat Examples Proper Coverage

Anything wrong here?

Tack coat Curing- left to cure until all volatiles evaporated Traffic- No traffic including construction vehicles Measurement for payment- Sq.meters

THIN BITUMINOUS LAYERS

BITUMINOUS SURFACE DRESSING (BSD) Purpose : One or two coats of bituminous application, each coat consisting of layer of bituminous binder followed by a cover of stone chips to serve as wearing course. The main functions of BSD are:  To serve as a thin wearing course of pavement  To prevent infiltration of surface water  To provide dust free pavement surface

SURFACE DRESSING Equipment : a)Self propelled mechanical sprayer for spraying bitumen. b)Self propelled or towed mechanical grit spreader to spread aggregate’s uniformly. c) Road roller 8-10 Ton smoothed wheeled or static weight vibratory. Construction Procedure : a)Preparation of base course. b)Bitumen is heated & sprayed with mechanical sprayer. c)Stone chips is spread with mechanical grit spreader. d)Surface is rolled with 8-10 ton roller. e)Application of second coat.

SURFACE DRESSING

BITUMEN BEING SPRAYED MECHANICALLY

STONE CHIPS BEING SPREAD BY MECHANICAL GRIT SPREADER

Opening to Traffic: Traffic is not allowed till following day.

POOR CONSTRUCTION

Tack Coat on Cracked Bituminous Surface

Thin Layer of MSS over WBM

Seal Coat

Seal Coat

SEAL COAT 1.Purpose : This is applied on bituminous surface for sealing the voids. 2.Types : a)Liquid seal coat (Type A). Application of layer of bituminous binder followed by layer of stone chips. b)Premixed seal coat (Type B). Thin application of fine aggregates premixed with bituminous binder.

SEAL COAT 3. Materials : a) Binder : Penetration grade satisfying IS-73. Qty/10m2 Item Bitumen (kg)

Bituminous Emulsion (kg)

Type A

9.8

15.0

Type B

6.8

10.5

b)

Aggregates . Should be clean, hard, durable and dry.

Item

Type A Type B

Size Passing Retained Qty/10m2 (mm) Sieve (mm) Sieve (mm) (m3)

6.7 -

11.2 2.36

2.36 0.180

0.09 0.06

4.

Equipment : a)Self propelled mechanical sprayer for spraying bitumen. b)Self propelled or towed mechanical grit spreader to spread aggregate’s uniformly. c)Road roller 8-10 Ton smoothed wheeled or static weight vibratory. 5.

Construction Procedure ( Type A) : a)Bituminous surface is cleaned. b)Bitumen is heated to 150-163о C & sprayed with mechanical

sprayer. c)Stone chips is spread with mechanical grit spreader. d)Surface is rolled with 8-10 ton roller.

6.

Construction Procedure ( Type B) : a)Bituminous surface is cleaned. b)Bitumen and aggregate are mixed thoroughly at suitable

temperature in mixing plant . c)Mix is transported to site and spread uniformly. d)Surface is rolled with 8-10 ton roller.

7.

Opening to Traffic: a)Type A. Following day. b)Type B. Soon after final rolling.

Open Graded Premix Carpet

OPEN GRADED PREMIX SURFACING 1. Purpose :To serve as wearing course, 20mm thick open graded premix surfacing material is laid and compacted. 2.

Material : a) Binders. Paving Bitumen as per IS-73. Bitumen Emulsion as per IS-8887. c) Aggregates. Physical requirement as per table 500-3 MORT&H specifications for roads.

3.

Equipment : a)Hot mix / cold mix plant for mixing binder and aggregates. b)Self propelled or towed mechanical sprayer. c)Pavers. d)Air compressor for cleaning. e)Road roller 8-10 Ton smoothed wheeled or static weight vibratory. 4.

Construction Procedure : a) Preparation of underlying surface. b) Tack coat. c) Preparation of premix in hot/cold mix plant. d) Spreading of premix by pavers or manually. e) Rolling with 8-10 ton roller. f) Application of seal coat.

OPEN GRADED PREMIX SURFACING

PREPARATION OF UNDERLYING SPREADING BITUMEN ON PREPARED SURFACE SURFACE : TACK COAT

OPEN GRADED PREMIX SURFACING

PREPARATION AND TRANSPORTATION OF MIX FROM HOT MIX PLANT

5.

LAYING THE MIX BY PAVER

Opening to Traffic: Traffic is not allowed until seal coat is laid.

Close Graded Premix Carpet

CLOSE GRADED PREMIX SURFACING 1. Purpose :To serve as wearing course, 20mm thick close graded premix surfacing material is laid and compacted. 2. Material : a) Binders. Paving Bitumen as per IS-73. c) Aggregates. Physical requirement as per table 500-3 & Gradation as per table 500-26 MORT&H specifications for roads.

3.

Equipment : a)Hot mix plant for mixing binder and aggregates. b)Self propelled or towed mechanical sprayer. c)Pavers. d)Air compressor for cleaning. e)Road roller 8-10 Ton smoothed wheeled or static weight vibratory. 4.

Construction Procedure : a)

Preparation of underlying surface.

b)

Tack coat.

c)

Preparation of premix in hot mix plant.

d)

Spreading of premix by pavers or manually.

e)

Rolling with 8-10 ton roller.

5.Opening to Traffic: Soon after final rolling.

Mastic Asphalt Work- Construction of single layer of mastic asphalt wearing course for road pavements and bridge decks - Mixture of well graded aggregates, filler and bitumen- plastic and voids less mass- impermeable surface - it cannot be compacted, and is spread rather than rolled. - fully waterproof and does not degrade as a result of weathering

Mastic Asphalt

Mastic Asphalt Requirements of Binder

Mastic Asphalt Grade and Thickness of Mastic Asphalt paving and Grading of Coarse Aggregate

0-5

Mastic Asphalt Grading of Fine aggregate including Filler

BITUMINOUS BINDER COURSE

504 BITUMINOUS MACADAM

Scope - consist of construction, in a single course, of compacted crushed aggregates premixed with a bituminous binder, to serve as base/binder course, laid immediately after mixing, on a base prepared previously in accordance with the requirement of these Specifications and in conformity with the lines, grades and cross-sections shown on the drawing or as directed by the Engineer

Core- BM

Materials Bitumen: - shall be paving bitumen of suitable penetration grade ( 35 to 90) as per IS : 73. -actual grade of bitumen to be used shall be decided by the Engineer appropriate to the region, traffic, rainfall and other environmental conditions. Aggregates Aggregates - crushed stone, crushed/ other hard material retained on 2.36 mm sieve stones. -clean, strong, durable, of fairly cubical shape and free from disintegrated pieces, organic or other deleterious matter and adherent coating. -poor adhesion- to be treated with anti-stripping agents

Coarse aggregates

Coarse aggregates- many fracture faces

Angular and non- angular aggregates

Bituminous macadam Fine aggregates- crushed/naturally occurring material /combination (2.36 to 75 micron)- clean, hard, durable..etc

TABLE 500-3. PHYSICAL REQUIREMENTS OF AGGREGATES FOR BITUMINOUS MACADAM

S.No.

Test

Test Method

Requirement

1.

Los Angeles Value*

IS : 2386 (Part-4)

40 per cent Maximum

2.

Aggregate Impact Value *

IS : 2386 (Part-4)

30 per cent Maximum

3.

Flakiness and Elongation Indices (Total) **

IS : 2386 (Part-1)

30 per cent Maximum

4.

Coating and Stripping of Bitumen Aggregate Mixtures

AASHTO T 182

Minimum retained coating 95 per cent

5.

Soundness (i) Loss with Sodium Sulphate 5 cycles (i)Loss with Magnesium Sulphate 5 cycles

IS : 2386 (Part-5)

12 per cent Maximum 18 per cent Maximum

6.

Water absorption

IS : 2386 (Part-3)

2 per cent Maximum

Abrasion

ABLE 500-4. AGGREGATE GRADING FOR BITUMINOUS MACADAM

IS Sieve Designation

Per cent by weight passing the sieve

Nominal size Layer thickness

Grading 1 40 mm 80-100 mm

45.0 mm 37.5 mm

100 90-100

--

26.5 mm

75-100

100

19 mm

-

13.2 mm 4.75 mm 2.36 mm 0.3mm 0.075 mm

Bitumen % wt of mix

35-61 13-22 4-19 2-10 0-8

3.1-3.4

Grading 2 19 mm 50-75 mm

90-100 56-88 16-36 4-19 2-10 0-8

3.3 -3.5

BM- Construction Operations Weather and seasonal limitations Preparation of the base -shall be prepared, shaped and conditioned to the specified lines, grades and cross-sections in accordance with Clause 501.8 (preparation of surface- Profile corrective course) and a priming coat where needed shall be applied in accordance with Clause 502 as directed by the Engineer Tack coat Preparation and transportation of mix Spreading RollingSurface finish and quality control check (clause 900) Protection of layer – another layer/ seal coat

Mixing and compaction Temperature

BM- Construction Operations

Arrangement for traffic Measurement for payment- cu.m

BITUMINOUS PENETRATION MACADAM Scope - consist of construction of one or more layers of compacted crushed coarse aggregates with alternate applications of bituminous binder and key aggregates in accordance with the requirements of these Specifications to serve as base/binder course and in conformity with the lines, grades and crosssections shown on the drawings or as directed by the Engineer. Thickness of an individual course -not exceed 75 mm.

BITUMINOUS PENETRATION MACADAM Bitumen: S- 35 to S-90 Aggregates Quantity of materials

COMPOSITION OF BITUMINOUS PENETRATION MACADAM IS Sieve Designati on

Per cent by weight passing the Sieve For 50mm compacted thickness Coarse Aggregate

Key Aggregate

For 75mm compacted thickness Coarse Aggregate

Key Aggregate

63

mm

-

-

100

-

53

mm

-

-

-

-

45

mm

100

-

58-82

-

26.5 mm

37-72

-

-

100

22.4 mm

-

100

5-27

50-75

13.2 mm

2-20

50-75

-

-

11.2 mm

-

-

-

5-25

5.6 mm

-

5-25

-

-

2.8 mm

0-5

0-5

0-5

0-5

Appro. Loose aggre(cu.m/m2) 0.06/0.015 Binder (kg/m2)

5

0.09/0.018 6.8

BITUMINOUS PENETRATION MACADAM Construction steps Steps Weather and seasonal Limitations Equipment- mechanical broom, compressor, self-propelled/trailed bitumen distributor, aggregate spreader, rollers Preparation of base Spreading coarse aggregate Compaction Application of binder material Application of key aggregates Surface finish and quality control Surfacing- other layer/seal coat Arrangement for traffic

MODIFIED PENETRATION MACADAM (MPM) 

Grouted/ Penetration type of construction



It can be laid in 50 mm or 75 mm thickness



Commonly practiced in Maharashtra

SIZE AND QUANTITY OF AGGREGATES FOR MPM Rate of application for 10 m2 area Aggregate Size

75 mm On Asphalt Surface

On W. B. M. Surface

50 mm On Asphalt Surface

40 mm size 0.9 cum hand broken metal

0.9 cum

12 mm size chips

0.18 cum 0.18 cum 0.18 cum

0.18 cum

0.6 cum

On W. B M. Surface 0.6 cum

Built Up Spray Grout

Materials to be used • Bitumen –Bitumen of paving grade complying with IS specifications for “paving bitumen” IS:73 and of penetration 35-90 • Course aggregate- crushed rock ,crushed gravel or other hard material retained on 2.36mm sieve. • They shall be clean, hard, durable, of cubical shape, free from dust and soft of friable matter, or other deleterious material • If selected aggregate have poor affinity for bitumen, then the bitumen is to be treated with anti stripping agent. • Source aggregate should be tested for stripping. • If crushed gravel is to be used >90%by weight retained on 4.75mm sieve shall have two fractured surfaces

Fine aggregate • Aggregate shall consist of crushed or naturally occurring material, or combination of two, passing 2.36mm sieve and retained on 75 micron sieve • Clean, durable, dry and free from dust, and soft or friable matter, organic or other deleterious matter

Construction operation Weather and seasonal limitations • To be suspended while free standing water is present on the surface to be covered, or during rain, fog and dust storms. • After rain, the bituminous surface, prime coat or tack coat ,shall be blown off with high pressure air jet to remove excess moisture or surface left to dry. • Laying not be done when air temperature is less 10°C, wind speed at any temperature exceeds 40kmph at 2m height Preparation of base. • The base on which the built up spray grout course is to laid shall be prepared, shaped and compacted • A prime coat where specified shall be applied over the base • A tack coat shall be applied

Spreading and rolling course aggregate for the first • Immediately after application of prime coat course aggregate shall be spread uniformly and evenly by a self propelled or tripper tail mounted aggregate spreader • The surface of the layer shall be checked with camber templates • At places where paver cannot go mix shall be spread, leveled using suitable hand tools • Layer thickness should be maintained carefully

Compaction •Rolling Should start soon after laying •Rolling Should be completed before the max temperature falls below minimum rolling temperature •Should ensure layer thickness and surface level •Rolling should commence at edges and progress towards centre (except at super elevation) •At super elevated portions progress shall be from lower to the upper edge •Should continue till roller marks are removed •Initial rolling with 8-10 ton smooth wheeled •Intermediate with 8-10 ton dead weight / vibratory or pneumatic tyred of 12-15 ton •Finishing with 6-8 ton smooth wheeled

Final surfacing

• The built up spray grout shall be provided with final surfacing within two days. • A seal coat is to be applied when there is a delay.

BUILT-UP SPRAY GROUT 

Two Layer Composite Construction of Compacted Coarse Aggregates



Application of Binder after each layer



Key aggregates on top of each layer



Thickness = 75 mm



Single Course in Pavement Structure

BUILT-UP SPRAY GROUT 

Preparation of Base to the Required Camber and Shape



Application of Primer



Application of Tack Coat



Spreading and Rolling First Layer of Coarse Aggregates (0.5 cu.m/10 sq.m)



Application of Binder - First Spray

(15 kg/10 sq.m)

BUILT-UP SPRAY GROUT 

Spreading and Rolling of Coarse Aggregates for the Second Layer



Application of Binder - Second Spray (15 kg/10 sq.m)



Application of Key Aggregates (0.13 cu.m/10 sq.m)



Roll and Apply Additional key aggregates, if required



Cover with a Seal Coat before opening to Traffic

BITUMINOUS MACADAM (BM) 

BM is carried out in a Hot Mix Plant, laid and compacted mechanically

 

There are two sets of grading, Grade I & II Quality control measures involves percentage of Bitumen & Mixing, Laying and Compaction temperature

GRADATION REQUIREMENTS FOR BM Grading Nominal Layer Thickness IS Sieve (mm) 45.0 37.5 26.5 19.0 13.2 4.75 2.36 0.300 0.075 Bitumen, per cent by weight of mix Bitumen Grade

I II 40 mm 19 mm 75-100 mm 50-75 mm Per cent Passing 100 -90-100 -75-100 100 -90-100 35-61 56-88 13-22 16-36 4-19 4-19 2-10 2-10 0-8 0-8 3.1 to 3.4 3.3 to 3.5 S 35-90

S 35-90

SEGREGATION IN MIX Segregation due to Single Drop

Must Avoid Segregation!

SEGREGATION IN BM MIX

PROPER LOADING

Sequence for Shorter End Dump Trucks

2

1

GOOD PAVEMENT SURFACE

EQUIPMENT REQUIRED

MODERN PAVER

SMOOTH WHEELED ROLLER

COMPACTION OF BITUMINOUS MIXES •

Lack of adequate compaction in field leads to reduce pavement life

•

Inadequate compaction of hot mix leads to early oxidation, ravelling, cracking and disintegration before its life expectancy is achieved

Stopping

e! Free Barbecu

End Dump Truck Operation

Raise bed, but keep tailgate closed until mix slides against it

End Dump Truck Operation

Open gate and continue to raise bed

Dense Bituminous Macadam (DBM)

Dense Graded Bituminous Macadam

• Used for base / binder course

• Work may require single or multiple layers • Thickness of a single layer is 50 -100mm

Materials • Bitumen – 60/70 or 80/100 or modified as specified – Minimum bitumen content by weight of mix • For NMAS 40mm --- 4.0% • For NMAS 25mm --- 4.5%

Aggregates • Coarse – Crushed rock / gravel – Cubical or F.I.+E.I. < 30% – Retained bitumen coating ≥ 95% – L.A.V. ≤ 35% & A.I.V. ≤ 27%

• Fine aggregate – Crushed / naturally occurring – Free from organic matter – Sand equivalent ≥ 50% • Filler – Generally rock dust/hydrated lime/cement – For filler other than lime/cement P.I. ≤ 4 – Lime acts as antistripping agent

• If coarse aggregate is gravel – Lime is added by 2% of aggregate weight – Fine aggregate is correspondingly reduced • Aggregate used is relatively well graded

Aggregate requirement

Dense Bituminous Macadam (DBM):

Dense Bituminous Macadam (DBM):

Gradation requirement

bitumen

Dense Bituminous Macadam (DBM):

Marshall Mix Design-criteria

Dense Bituminous Macadam (DBM):

Binder content- as per mix design Agg. retained on 26.5- 26.5 to 22.4

For 40mm- use modified Marshall method- MS 2(AI)

Dense Bituminous Macadam (DBM): Plants-trials

Dense Bituminous Macadam (DBM): Steps Weather and seasonal limitations Preparation of base Geosynthetics Stress absorbing layer Prime coat Tack coat Mixing and transportation of the mixture

….contd Steps Spreading Rolling Opening top traffic Surface finish and quality control of work Arrangements for traffic Measurements for payment

Bituminous Concrete

Bituminous Concrete

Aggregate requirement (wet sieving method)

Bituminous Concrete

Gradation requirement

Bituminous Concrete • Used for wearing / profile corrective course • Work may require single or multiple layers • Thickness of a single layer is 25-100mm

Materials •

Bitumen – 60/70 or modified as specified – Bitumen content by weight of mix • For NMAS 13mm --- 5-6% • For NMAS 19mm --- 6-7%

•

Coarse – Crushed rock / gravel – Cubical or F.I.+E.I. < 30% – Retained bitumen coating ≥ 95% – L.A.V. ≤ 30% & A.I.V. ≤ 24%

• Fine aggregate – Crushed / naturally occurring – Free from organic matter – Sand equivalent ≥ 50% • Filler – Generally rock dust/hydrated lime/cement – For filler other than lime/cement P.I. ≤ 4 – Lime acts as anti stripping agent

Continued…

• If coarse aggregate is gravel – Lime is added by 2% of aggregate weight – Fine aggregate is correspondingly reduced • Aggregate used is relatively well graded

Mix requirements (Table 500-16) Min stability (KN at 60°C)

9.0

Minimum flow (mm)

2

Maximum flow (mm)

4

Compaction level (no. of blows) Percent air voids

75(each face) 3-6

VMA (NMAS 13mm)

13 - 15

VMA (NMAS 19mm)

12 - 14

VFB

65 - 75

Loss of stability on immersion 60°C

Min.75% retain

• Mixing , laying and compaction operations are similar to them explained for DBM Opening to traffic • Traffic shall not be allowed for first 24 hours after laying & completion of compaction of the mix

Thank you