Flyash Concrete.docx

GOVERNMENT POLYTECHNIC, SORABA

FLYASH MIX CONCRETE

CHAPTER 1 INTRODUCTION 1.1 General Cement, fine aggregate, coarse aggregate are essential needs for any construction industry. Fine aggregate is a major material used for preparation of mortar and concrete and plays a most important role in mix design. In general consumption of natural fine aggregate is high, due to the large use of concrete and mortar. Hence the demand of fine aggregate is very high developing countries to satisfy the rapid infrastructure growth. The developing country like India facing shortage of good quality fine aggregate and particularly in India, fine aggregate deposits are being used up and causing serious threat to environment as well as society. Rapid extraction of fine aggregate from river beds and causing so many problems like losing water retaining soil strata, deepening of the river beds and causing bank slides, loss of vegetation on the bank of river, disturbs the aquatic life as well as disturbs agriculture due to lowering the water table in the well etc are some of the examples. The heavy exploitation of river fine aggregate for construction purposes in Sri Lanka as laid to various harmful problems option for various river fine aggregate alternatives, such as offshore fine aggregate. Fine aggregate also has been made. physical as well as chemical properties of fine aggregate affect the durability, workability and also strength of concrete, so fine aggregate is a most important constituent of concrete and cement motor. Generally river fine aggregate or pit fine aggregate are used as fine aggregate4 bin mortar and concrete together fine and coarse aggregate make about 75-80% of total volume of concrete and hence it is very important to fine suitable type and good quality aggregate nearby site. Recently natural fine aggregate is becoming a very costly material because of its demand in the construction industry due to this condition research began for cheap and easily available alternative material to natural fine aggregate. Some alternative materials have already been used. Even through of shore fine aggregate is actually used in many counties such as the UK, Sri Lanka, continental Europe, India and Singapore most of records regarding use of this alternative found manly lesser extent of practice in the construction field. The word is resting over a land fill oaf waste hazardous materials which may substitutes of natural fine aggregate. Irrespective of position, location, scale, type of any structure, concrete is the base for construction activity. In fact, concrete is the second largest consumable material after water, with nearly free tones used annually for each person on the earth. In consumes an DEPT. OF CIVIL ENGG

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estimated 450 million cubic meter of concrete annually and which approximately comes to 1 tones owner Indian. We still have a long way to global consumption go by global consumption levels but do we have enough fine aggregate to make concrete and mortar? Value of constructing industry grew at strugaring rate of 15% annually even in the economic slowdown and as contributed to 7-8% of the countries. GDP(at current prices) for the past eight years thus, it is becoming increasingly discomforting for people like common people who talk about greening the industry to have no practical answer to his very critical question. In fact we have been sitting land fill of possible substitutes for fine aggregate. Industrial waste by products almost all industry which have been rising hazardous problem both for the environment, agriculture and women health and have major used in construction activity which may be use full for not only from the economy point of view but also took reserve the environment.

1.2 Fly Ash Mix Concrete Fly ash is very much similar to volcanic ashes used in production of the earliest known hydraulic cements about 2,300 years ago. Those cements were made near the small Italian town of Pozzuoli - which later gave its name to the term “pozzolan”. A pozzolan is a siliceous or siliceous / aluminous material which when mixed with lime and water forms a cementitious compound. Fly ash is the best known, and one of the most commonly used, pozzolans in the world. Fly ash is the notorious waste product of coal based electricity generating thermal power plants, known for its ill effects on agricultural land, surface and sub-surface water pollution, soil and air pollution and diseases to mankind. Researchers have proposed few ways of reusing fly ash for variety of application. One of the most common reuse of fly ash is in cement concrete. Fly ash particles are almost totally spherical in shape, allowing them to flow and blend freely in mixtures. That capability is one of the properties making fly ash a desirable admixture for concrete. These materials greatly improve the durability of concrete through control of high thermal gradients, pore refinement, depletion of cement alkalis, resistance to chloride and sulphate penetration, and continued micro structural development through a long-term hydration and pozzolanic reaction. The utilization of byproducts as the partial replacement of cement has important economical, environmental and technical benefits such as the reduced amount of waste materials, cleaner environment, reduced energy requirement, durable service performance during service life and cost effective structures.

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In the present era of growth and development, progress is taking place in all the fields. But, in the light of progress, man is ignoring nature and harming it. Construction area, with the use of virgin materials like cement, is also posing the threat of global warming and environmental degradation. The challenge in front of civil engineering community is to provide sufficient, economical and comfortable infrastructure without causing any hardship for environment. Taking sustainable development in view, an attempt has been made to reduce the use of cement in concrete by replacing it with otherwise waste materials such as fly ash, slag, silica fume and rice husk. The use of fly ash in concrete has been encouraged all over the world. Though this has been tried at some places in India but the percentages replacements of cement by fly ash are very small and only less than 25% of total fly ash produced is being utilized. A confidence is required to be built up in developing countries like India to make use of fly ash concrete in various fields of construction.

Chemical Requirements of Fly Ash (As per BIS) SN

Characrteistics

Requirements Siliceous Fly Ash

1

SiO2+Al2O3+Fe2O3

Calcareous Fly Ash

(% by mass, 70

50

Min.) 2

SiO2 (% by mass, Min.)

35

25

3

Reactive silica (% by mass, Min.)

20

20

4

MgO (% by mass, Max.)

5

5

5

SO3 (% by mass, Max.)

3

3

6

Na2O (% by mass, Max.)

1.5

1.5

7

Total Chlorides (% by mass, Max.)

0.05

0.05

8

Loss on Ignition (% by mass, Max.)

5

5

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CHAPTER 2 LITERATURE REVIEW Chatterjee, (2011) reported that about 50 % of fly ash generated is utilized with present efforts. He also reported that, one may achieve up to 70% replacement of cement with fly ash when high strength cement and very high reactive fly ash is used along with the sulphonated naphthalene formaldehyde super plasticizer. He reported improvement in fly ash property could be achieved by grinding and getting particles in sub microcrystalline range.

Bhanumathidas, &Kalidas, (2002) with their research on Indian fly ashes reported that the increase in ground fineness by 52% could increase the strength by 13%. Whereas, with the increase in native fineness by 64% the strength was reported to increase by 77%. Looking in to the results it was proposed that no considerable improvement of reactivity could be achieved on grinding a coarse fly ash. Authors also uphold that the study on lime reactivity strength had more relevance when fly ash is used in association with lime but preferred pozzolanic activity index in case of blending with cement.

Subramaniam, Gromotka, Shah, Obla& Hill, (2005) investigated the influence of ultrafine fly ash on the early age property development, shrinkage and shrinkage cracking potential of concrete. In addition, the performance of ultrafine fly ash as cement replacement was compared with that of silica fume. The mechanisms responsible for an increase of the early age stress due to restrained shrinkage were assessed; free shrinkage and elastic modulus were measured from an early age. In addition, the materials resistance to tensile fracture and increase in strength were also determined as a function of age. Comparing all the test results authors indicated the benefits of using ultrafine fly ash in reducing shrinkage strains and decreasing the potential for restrained shrinkage cracking.

Hwang, Noguchi &Tomosawa, (2004) based on their experimental results concerning the compressive strength development of concrete containing fly ash, the authors concluded that the pores in concrete reduce by addition of fly ash as replacement of sand. (Siddique, 2003) carried out experimental investigation to evaluate mechanical properties of concrete mixes in which fine aggregate (sand) was partially replaced with class F fly ash. Fine aggregate was replaced with five percentages (10%, 20%, 30%, 40% and 50 %) of class F fly ash by weight.

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The test result showed that the compressive strength of fly ash concrete mixes with 10% to 50% fine aggregate replacement with fly ash were higher than control mix at all ages. Also the compressive strength of concrete mixes was increasing with increase in fly ash percentages. This increase in strength due to replacement of fine aggregate with fly ash was attributed to pozzolanic action of fly ash. The splitting tensile strength also increased with increase in percentage of fly ash as replacement of fine aggregate. The tests on flexural strength and modulus of elasticity also showed improvement in the results as compared to control concrete.

Namagg&Atadero, (2009) described early stages of a project to study the use of large volumes of high lime fly ash in concrete. Authors used fly ash for partial replacement of cement and fine aggregates. Replacement percent from 0% to 50% was tested in their study. They reported that concrete with 25% to 35% fly ash provided the most optimal results for its compressive strength. They concluded that this was due to the pozzolanic action of high lime fly ash. (Jones & McCarthy, 2005) made an extensive laboratory based investigation in to unprocessed low lime fly ash in foamed concrete, as a replacement for sand. For a given plastic density, the spread obtained on fly ash concretes were up to 2.5 times greater than those noted on sand mixes. The early age strengths were found to be similar for both sand and fly ash concrete, the 28-day values varied significantly with density. The strength of fly ash concrete was more than 3 times higher than sand concrete. More significantly while the strength of sand mixes remained fairly constant beyond 28 days, those of fly ash foamed concrete at 56 and 180 days were up to 1.7 to 2.5 times higher than 28 days values respectively.

Rebeiz, Serhal& Craft, (2004) reported investigation on the use of fly ash as replacement of sand in polymer concrete. In the weight mix design 15% sand was replaced by fly ash. This replacement of 15% sand with fly ash by weight increased compressive strength by about 30%. Also there was improvement in the stress strain curve. They also reported good surface finish due to addition of fly ash as replacement of sand which also reduce permeability and have an attractive dark colour. Flexural strength of steel reinforced polymer concrete beams was increased by 15%. When subjected to 80 thermal cycles polymer concrete with fly ash exhibits slightly better thermal cycling resistance (about 7% improvement) than polymer concrete without fly ash.

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(Rao, 2004) discussed the need to use about 650 kg/cu.m of fine material to make self compacting concrete. This also requires fine aggregates more than 50% of total aggregate so that coarse aggregate can float in the fine material. This requirement of fine materials can be easily fulfilled by use of fly ash.

2.1 SUMMARY OF REVIEW OF LITERATURE From above investigation compared to conventional concrete in fly ash mix concrete by using optimum amount of fly ash is significantly increase in compressive strength, Split tensile strength, modulus of elasticity and crack resistance. So fly ash were added in various percentages like 0%,40 %, 50%, 60%, 70% and 80% by weight of coarse aggregate. The fly ash percentage increases the compressive strength of cube and split tensile strength of the cylindrical specimen also increases. One of the important advantages with fly ash concrete is the resistance to alkali aggregate reaction (AAR). Increasing AAR because of fly ash or increased fly ash content is not registered by any authors in this literature study. Several successful field constructions with high volume Class F fly ash concrete are mentioned. Even if the use of fly ash has a lot of advantages there always will be events of less favourable experience, because of different cement types, fly ashes, admixtures, aggregates, environment and temperature. However, there are few examples of poor field constructions with fly ash concrete. Perhaps this is because of its good properties of the fly ash concrete used in the constructions, or the reason is no one wants to report failed projects.

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CHAPTER 3 EXPERIMENTAL INVESTIGATION 3.1 Objects of testing The main object of testing is to know the behavior of Fly ash mixed concrete in concrete in fresh as well as in hardened state. Concrete a is prepared by adding the Fly ash in various percentage from 0%, 40%, 50%, 60%, 70%, 80%. The main parameters studied were: 1.

Workability of fresh concrete (slump and compaction factor and vee-bee test)

2.

Cube compressive strength

3.

Spilt tensile strength

4.

Density of concrete

5.

Modulus of elasticity of concrete

3.2 Materials The materials used in this investigation are: Cement, fly ash, Fine aggregate, Coarse aggregate, Water, Super plasticizer. Cement OPC 43 grade cement conforming to IS: 8112 from a single batch is used throughout the course of the project work. The properties of cement used are shown in table 3.1 Fly Ash In this study, The fly ash is collected from the poly fibers industry. Fly ash utilization in concrete as partial replacement of cement. The specific gravity is obtained from the test is equal to 1.87

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Fine aggregate Locally available river fine aggregate belonging to zone 2 of IS 383-1970 is used for the present work. The sieve analysis data of fine aggregate are shown in table 3.2 Coarse aggregate Crushed ballast stone of size 12mm and 20mm down confirming to IS 383 - 1970 is used in this project the sieve analysis and properties are tested and tabulated in table 3.4 and table 3.5 . Water Portable water is used in the present investigation for both casting and curing .pH of water is between 6.5 – 8.5 Super plasticizers Super plasticizer conforming to IS: 9103-1999 FOSROC Conplast SP 430 DIS (Sulphonated Naphthalene Formaldehyde) Batch No. IN1MF00299416 3.3 Mix proportion of concrete Mix design was carried out using the proportions of ingredients for M20 grade as per IS 10262- 2009; “GUIDELINES FOR CONCRETE MIX DESIGN PROPORTIONIGN” gives the minimum cement content. Mix design calculations has been shown in appendix- A and mix proportions for different mixes used are shown in Table 3.9 3.4 Casting of concrete cube and cylindrical mould Cube moulds of size 150mmX150mmX150mm and Cylindrical mould of size 150mm dia. and 300mm length are used for casting the concrete. The moulds are cleaned and before casting greasing to be applied on all the internal surfaces. All the cube moulds are filled in 3 layers. The heights of the mould and for each layer 1/3 rd of each layer 25 blows are given with DEPT. OF CIVIL ENGG

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the help of tamping rod over the entire cross section of the mould uniformly. After filling and compacting the mould, the top surface is made smooth and kept for drying for 18 hours. Fly ash by weight of cement 0%, 40%, 50%, 60%, 70% and 80% are designated as 1FA0, 1FA40, 1FA50, 1FA60, 1FA70, 1FA80. one cylindrical and two cube moulds are casted for each percentage of Fly ash. A total no of 18 moulds are casted with W/c 0.4 for 0%, 40%, 50%, 60%, 70% and 80% of Fly ash by weight of cement for 7 and 28 day compression and split tensile testing. Batching, Mixing and Preparation of concrete are shown in Image 3.1 and 3.2

3.5 Curing specimens Immersion method of curing is adopted for curing. Specimens are removed after 24 hour of casting from the moulds and are placed in tank containing water for 7 and 28 days of curing. After the curing period, specimens are removed from the tank and the surface moisture can be removed by wiping the surface with cloth and make sure that the specimens are in surface dry condition. Specimens kept for curing are shown in Image 3.3

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CHAPTER 4 TESTS OF CONCRETE SPECIMENS 4.1 TESTS ON FRESH CONCRETE 4.1.1 SLUMP TEST (As per IS: 1199-1959) The internal surface of the slump cone shall be thoroughly cleaned. The mould shall be placed on smooth, horizontal, rigid and non-absorbent surface. The mould shall be filled in four layers, each approximately one-quarter of the height of the mould. Each layer shall be tamped with 25 stokes of the rounded end of the tamping rod. The stokes shall be distributed in a uniform manner over the cross section of the mould and for the second and subsequent layers shall penetrate into a underlying layer. The bottom layer shall be tamped thought its depth. After the top layer has been rodded, the concrete shall be struck off level with a trowel or the tamping rod, so the mould is exactly filled. The mould shall be removed from the concrete immediately by rising its slowly and carefully in s vertical direction. This allows to concrete subside and the slump shall be measured immediately by determining the difference between the height of the mould and that of the highest point of the specimen being tested. Slump in mm = (h - h1) Where, h = height of concrete in mm h1 = height of subsided concrete in mm Degree of workability for different slump value has been tabulated in table 4.1

Slump

Degree of workability

0-25

Very low

25-50

Low

50-100

Medium

100-150

High

>150

Very high

Image 4.1 Slump test DEPT. OF CIVIL ENGG

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4.1.2 COMPACTION FACTOR TEST (as per IS: 1199-1959) Weigh the empty cylinder of the compaction factor apparatus as W1 placee it below the lower hopper. For mixes are to be prepare with w\c ratio. All hoppers are cleaned, greased and pour the concrete mix in the top hopper. Remove the tap door of the upper hopper and then removed door of the lower hopper. The concrete gets collected in the cylinder Now, gently level the cylinder and note down the weight the cylinder as W2. Remove all concrete then refill by 3 layers by providing 25 blows per each layer now take down the weight W3. Compaction factor is obtained by the following formula (W2 - W1) / (W3 - W1) Where, W1 = weight of empty cylinder W2 = weight of empty cylinder + partially compacted concrete W3 = weight of empty cylinder + fully compacted concrete Degree of workability for different Compaction factor value has been tabulated in table 4.2 Compaction factor (20mm down

Degree of workability

aggregate) 0.66

Extremely low

0.78

Very low

0.85

Low

0.92

Medium

0.95

High

>0.95

Very high

Image 4.2 Compaction factor machine

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4.1.3 VEE BEE CONSISTOMETER TEST (as per IS: 1199-1959) 1. A slump test shall be performed in the sheet metal cylindrical pot of the consistometer. 2. The glass disc attached to the swivel arm shall be moved and placed just on the top of the slump cone in the top. 3. Before the cone is lifted up the position of the concrete cone shall be noted by adjusting the glass disc attached to the swivel arm. 4. The cone shall then be lifted up and the slump noted on the graduated rod by lowering the glass disc on top of the concrete cone. 5. The electrical vibrator shall then be switched on and the concrete shall be allowed to spread out on the top. 6. The vibration shall then be continued until the whole concrete surface uniformly adverse to the glass disc and the time taken for this to be attained shall be noted with a stop watch. 7. The time recorded in seconds.

Degree of workability for different Vee bee seconds has been tabulated in table 4.3

Workability description

Vee bee degree, second

Extreme dry

40 to 25-20

Very stiff

20-10

Stiff

10-5

Stiff plastic

5-3

Plastic

3-1

Flowing

<1

Image 4.3 Vee-bee consistometer

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4.2 TESTS ON HARDENED CONCRETE 4.2.1 CUBE COMPRESSION TEST (As per IS: 516-1959) Cube specimens are used to determine characteristic compressive strength. The cubes are tested in compression testing machine of capacity 1000 kN. The load is applied without shock, increased gradually at a rate of approximately 140 kg/cm2/min, the two opposite sides of the cubes are compressed (top and bottom surface). The load is applied until the specimen fails or breaks. The ultimate load shall be recorded and compressive strength can be calculated by using formula. Cube Compressive Strength (N/ mm2)

=P/A

Where, P

=

Ultimate load at failure in N

A

=

Area of concrete specimen (150 X 150 = 22500) in mm2

Image 4.4 Cube Compressive Test

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4.2.2 SPLITTING TENSILE STRENGTH TEST (As per IS: 5816-1999) Cylindrical specimens are used to determine split tensile strength. The specimens are tested in compression testing machine of capacity 1000 kN. This test is carried out by placing a cylindrical specimen horizontally between the loading surface of a compression testing machine and the load is applied until failure of the cylinder, along the vertical diameter. The load is applied without shock, increased gradually at the rate approximately 1.2 to 2.4 N/mm2/min. The ultimate load shall be recorded and Split tensile strength can be calculated by using formula. Split tensile strength (N/ mm2)

= (2 x P) / (π X d X L) = P X 1.414 X10-5

Where, P

=

Ultimate load at failure in N

d

=

Diameter of cylindrical specimen in mm (150mm)

L

=

Length of cylindrical specimen in mm (300mm)

Image 4.5 Split Tensile Strength of Specimen DEPT. OF CIVIL ENGG

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4.2.3 DETERMINATION OF DENSITY OF CONCRETE

The density of concrete is determined in hardened state. The density of concrete is calculated by the following formula. Density of Concrete (kN/m3) = W/ V Where, W

=

Weight of concrete in kN or kg

V

=

Volume of concrete in m3

For Cube Mould, Volume = 150 X 150 X 150 = 3375000 mm3 or 0.003375 m3 For Cylindrical Mould, Volume = (π X 1502 / 4) X 300 = 5301437.60 mm3 or 0.005301 m3

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CHAPTER 5 RESULTS AND DISCUSSIONS

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5.3 TEST RESULTS OF MATERIALS TABLE 5.1.1: Properties of Cement Sl. No.

Properties

Results

1

Specific gravity

3.13

2

Fineness of cement

6.66%

3

Normal consistency

28%

4

Initial setting time

30 min

5

Final setting time

10 hrs

6

Soundness Test

10 mm

Fine Aggregate TABLE 5.2.1: Sieve Analysis of Fine Aggregates Sl. No.

IS sieve size (mm)

Cumulative % passing

1

4.75

99.3

2

2.36

87.6

3

1.18

57.8

4

600

20.9

5

300

0.4

6

150

0.5

7

Pan

0

TABLE 5.2.2: Properties of Fine Aggregates Sl. No.

Properties

Results

1

Bulking of fine aggregate

42%

2

Specific gravity

2.83

3

Bulk density

Kg/ltr

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Coarse Aggregates TABLE 5.3.1: Sieve Analysis 20 mm down size coarse aggregates Sl. No.

IS sieve size (mm)

Cumulative % passing

1

20

93.6

2

12.5

15.1

3

10

6.35

4

4.75

0.2

5

Pan

0

TABLE 5.3.2: Sieve Analysis 12 mm down size coarse aggregates Sl. No.

IS sieve size (mm)

Cumulative % passing

1

12.5

88.3

2

10

42.1

3

4.75

9.71

4

Pan

------

TABLE 5.3.3: Properties of coarse aggregates Sl. No.

Properties

Results

1

Specific gravity

2.62

2

Bulk density

1.674

3

Percentage of voids

36.06%

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TABLE 5.4: For w/c ratio 0.4 mix proportion for different mixes

Fly Ash (%)

1FA0

1FA40

1FA50

1FA60

1FA70

1FA80

Weight (kg)

Cement Fine aggregate (kg/m3)

(kg/m3)

370

Coarse Aggregate

(kg/m3)

(kg/m3)

(% by wt. of cement)

12mm

20mm

790

476

714

244.2

680

408

612

203.5

621

376

564

162.8

496

357.60

536.2

122.1

473

285.60

428.4

284.9

81.4

531

320.6

480.6

325.6

0

Proportion Weight (kg)

162.8

Proportion Weight (kg)

203.5

Proportion Weight (kg)

244.2

Proportion Weight (kg) Proportion Weight (kg) Proportion

TABLE 5.5: Workability of Fresh Concrete

Designation

Slump* (mm)

Compaction factor*

Vee-bee seconds*

1FA0

10

0.80

25

1FA40

10

0.78

22

1FA50

10

0.72

17

1FA60

10

0.69

13

1FA70

10

0.74

11

1FA80

10

0.76

11

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TABLE 5.6: Cube Compressive Strength Cube Compressive Strength* (N/mm2)

Designation

7 Days

28 Days

1FA0 1FA40 1FA50 1FA60 1FA70 1FA80

* indicates average of three specimens TABLE 5.7: Hardened concrete properties of Cube Specimens 7-day Designation

Density* (KN/m3)

28-day

Elastic

Flexural

modulus*

Strength

(N/mm2)

(N/mm2)

Density* (KN/m3)

Elastic

Flexural

modulus*

Strength

(N/mm2)

(N/mm2)

1FA0 1FA40 1FA50 1FA60 1FA70 1FA80

* indicates average of three specimens

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TABLE 5.8: Split Tensile Strength Split Tensile Strength * (N/mm2) Designation 7 Days

28 Days

1FA0 1FA40 1FA50 1FA60 1FA70 1FA80

* indicates average of three specimens TABLE 5.9: Hardened concrete properties of Cylindrical Specimens

Designation

7 day

28 days

Density*

Density*

(KN/m3)

(KN/m3)

1FA0 1FA40 1FA50 1FA60 1FA70 1FA80

* indicates average of three specimens

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Figure F5A: Slump v/s Percentage of Flyash

Figure F5B: Compaction factor v/s Percentage of Flyash DEPT. OF CIVIL ENGG

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Figure F5C: Vee-bee seconds v/s percentage of flyash

Figure F5D: 7 day density of cubes v/s

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Figure F5E: 28 day density of cubes v/s

Figure F5F: 7 day density of cylindrical specimen v/s

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Figure F5G: 28 day density of cylindrical specimen v/s P

Figure F5H: 7 day cube compressive strength v/s DEPT. OF CIVIL ENGG

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Figure F5I: 28 day cube compressive strength v/s

Figure F5J: 7 day specimen split tensile strength v/s DEPT. OF CIVIL ENGG

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Figure F5K: 28 day specimen split tensile strength v/s

Figure F5L: Cube Compressive strength of 7 and 28 day test results DEPT. OF CIVIL ENGG

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Figure F5M: Split tensile strength of 7 and 28 day test results

Figure F5N: Modulus of elasticity v/s percentage of for 7 day compressive test DEPT. OF CIVIL ENGG

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Figure F5O: Modulus of elasticity v/s percentage of for 28 day compressive test

Figure F5P: 7 day flexural strength of cube v/s percentage of DEPT. OF CIVIL ENGG

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Figure F5Q: 7 day flexural strength of cube v/s percentage of

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CHAPTER 6 CONCLUSIONS

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APPENDIX- A MIX DESIGN (IS CODE OF PRACTICE-10262: 2009) Stipulations for proportioning

1. Grade designation

:

M20

2. Type of cement

:

OPC 43 grade

3. Maximum nominal size of aggregate :

:

20mm

4. Minimum cement content

:

320 kg/m3

5. Maximum water-content ratio

:

0.45

6. Exposure condition

:

Mild

7. Method of concrete placing

:

Conventional

8. Degree of supervision

:

Crushed angular aggregates

9. Maximum cement content

:

450 kg/m3

10. Maximum water content

:

186 kg/m3

11. Chemical admixture

:

Super plasticizer

 Target strength for mix proportioning: f1ck

= fck+1.65s

f1ck

=target average compressive strength at 7 days and 28 days,

f ck

= characteristics compressive strength at 28 days = 20 N/mm2 (for M20 concrete)

S

= standard deviation

Refer table 1 of IS: 10262:2009, Standard deviation for M20 grade of concrete, S = 4 N/mm2 f1ck

=20 + 1.65 X 4

fck

= 26.6 N/mm2 

Selection of water cement ratio :

Maximum water cement ratio =0.45

Based on experience, adopt Water - Cement Ratio = 0.40 (As per IS 456:2000, For RCC work maximum water cement ratio for exposure, a) Mild = 0.55, b) Moderate = 0.50, c) Sever = 0.45, d) Very severe = 0.45, e) Extreme =0.40) 0.4 < 0.45 hence o. k DEPT. OF CIVIL ENGG

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 Selection of water content : Refer table 2 of IS: 10262:2009, Note down the value of the quantity of water content for 20mm aggregate = 186 liter (25to 50mm slump range) The required water content may be established by an increase of about 3% for every additional 25mm slump, i.e., 6% for additional 50mm slump, since slump given 100m Estimated water content for 100mm slump = 186 + 6 / 100 X 186 = 197.16 liters Since super plasticizer is used, the water content can be reduced up 25%. Based on trials with super plasticizer water content reduction of 25% has been achieved. (Percentage of water content =100-25 =75 ) Hence, the arrived water content =197.16 X 0.75 =148 liters 

Calculation of cement content : Cement content = Water content / Water Cement ratio = 148/0.4 =370 kg /m3

(As per IS 456 :2000, For RCC work Minimum cement content in kg /m3 for exposure 1) Mild =300, 2) Moderate =300, 3) Severe = 320, 4) Very severe = 340, 5) Extreme = 360) In this case Exposure condition given in the problem as Mild ( for reinforced concrete),

Therefore Minimum cement content should be 300kg /m3 370kg /m3 > 300kg /m3 hence o.k. 

Proportion of volume of coarse aggregate and fine aggregate content

Refer Table 2 of IS 10262 : 2009, note down volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone 1) for water cement ratio of 0.5 =0.6 In the present case water cement ratio is =0.40. For 0.1 change water cement ratio, volume of coarse aggregate is increased by = 0.02. Therefore, corrected proportion of volume of coarse aggregate for the water cement ratio of 0.40 = 0.60+0.02 = 0.62.

Therefore, volume of coarse aggregate = 0.62 Volume of fine aggregate content = 1-0.62 =0.38.

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Mix calculation A. Volume of concrete

=

1 m3

B. Volume of cement

=

(mass of concrete/specific Gravity) X (1/1000)

C. Volume of all in aggregate

=

=

(370/3.15) X (1/1000)

=

0.117 m3

(mass of water/specific Gravity) X (1/1000)

D.

=

(148/1) X (1/1000)

=

0.148 m3

=

(mass of chemical admixture/

Super plasticizer (2% by mass of Cementatious material)

Specific gravity) X (1/1000)

E.

F.

Volume of all aggregate

Mass of coarse aggregate

=

(7.4/1.21) X (1/1000)

=

0.006115 m3

=

A-(B+C+D)

=

1-(0.117+0.148+0.006115)

=

0.7289 m3

=

E X volume of coarse aggregate

X specific gravity X 1000

= G.

=

0.7289 X 0.62 X2.7 X 1000

=

E X volume of fine aggregate X

1220.17 kg

Mass of fine aggregate

Specific gravity X 1000 =

0.7289 X 0.38 X 2.6 X 1000 =

720.153 kg

Mix proportion Cement

=

370 kg/ m3

Fine aggregate

=

720.153 ~ 721kg

Coarse aggregate

=

1190 ~ 1220 kg

Chemical admixture

=

0.6% by weight of cement

Water cement ratio

=

0.4

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Mix proportion for 1 mould of 150 X 150 X 150 mm Cement

=

1.25 kg

Fine aggregate

=

2.43 kg

Coarse aggregate

=

4.12 kg

Chemical admixture

=

7.48 ml

Water cement ratio

=

0.4

Mix proportion for 1 cylindrical mould 150mm dia 30 cm Cement

=

2 kg

Fine aggregate

=

3.82 kg

Coarse aggregate

=

6.5 kg

Chemical admixture

=

12 ml

Water cement ratio

=

0.4

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COST ANALYSIS Conventional concrete Description

Quantity

Rate per

Amount

unit (Rs)

(RS)

Fly Ash Mix Concrete Quantity

Rate per

Amount

unit (Rs)

(RS)

Cement Fine aggregate Coarse aggregate Fly ash Super plasticizer Total =

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IMAGES

Image P1: Mixing of concrete

Image P2: Compaction factor test

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Image P3: Casting of moulds

Images P4: Curing of concrete DEPT. OF CIVIL ENGG

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Images P5: Cylindrical specimen before Applying Loa

Image P6: Failure of Cylindrical Specimen

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ImagesP7: Failure Load of concrete cube

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 REFERENCES  Bhanumathidas N and Kalidas, N, (2002) Fly Ash for Sustainable Development, Institute for Solid Waste Research and Ecological Balance . Chatterjee, A. K. (2011), Indian Fly Ashes: Their Characteristics and Potential for MechanochemicalAcivation for Enhanced Usability, Journal of Materials in Civil Engineering, June 2011, pp-783-788.  Hwang, K., Noguchi, T., and Tomosawa, F. (2004) Prediction model of compressive strength development of fly ash concrete, Cement and Concrete research, vol-34, pp2269-2276.  Malhotra, V. M. and Ramezanianpour, A. A. (1994) Fly Ash in Concrete, Second Edition, Natural Resources, Canada.  Siddique, R. (2004), Performance Charectristics of High Volume Class F Fly Ash Concrete, Cement and Concrete Research, Vol. 34, pp 487- 493  Subramaniam, K. V., Gromotka, R., Shah, S. P., Obla, K. and Hill, R. (2005) Influence of Ultrafine Fly Ash on the Early Age Response and the Shrinkage Cracking Potential of Concrete, Journal of Materials in Civil Engineering, Jan-Feb 2005, pp-45-53.  IS.383, “Specifications for Coarse and Fine Aggregates from Natural Sources for Concrete,” Bureau of Indian Standards, New Delhi, 1970.  I.S.1489-1991, “Specification for Portland Pozzolona cement Part 1 Fly ash based (Third Revision)”, Bureau of Indian Standard, New Delhi, 1991.  I.S.10262-1982, “Indian Standard Recommended Guidelines for Concrete Mix Design”, Bureau of Indian Standard, New Delhi, 1983.  IS:1199-1959 methods of sampling and analysis of concrete.  IS 456-2000- plain and reinforced concrete- code of practice.  IS 23866(Part 1): 1963 Methods of test for aggregates for concrete: Part 1 Particle size and shape.  IS 2386 (Part 3):1963 Methods of test for aggregates for concrete: Part 3 Specific gravity, density, voids, absorption, and bulking.  IS 2430:1986 Methods for sampling of aggregates for concrete.  IS 5816:1999 Method of test for splitting tensile strength of concrete.  IS 7325:1974 Specification for apparatus for determining constituents of fresh concrete.  IS 7320:1974 Specification for concrete slump test apparatus.  IS 8112:1989vSpecification for 43 grade ordinary Portland.

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 IS 9013:1978 Method of making, curing, and determining compressive strength accelerated cured concrete test specimens.  IS 9103:1999 Specification for admixture for concrete.  IS 10086:1982 Specification for moulds for use in tests of cement and concrete.  IS 10262:2009 Guidelines for concrete mix proportioning.  IS 10510:1983 Specification for Vee-Bee consistometer.  IS 13311 (Part 2):1992 Methods of non- destructive testing of concrete : Part-2 Rebound hammer.  IS 14959 (part 1): 2001 Method of test for determination of water soluble and acid soluble chlorides in mortar and concrete: part 1 Fresh mortar and concrete.  Shetty M S(2003) Concrete Technology, S.Chand and Company Ltd, New Delhi.

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