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International e-Journal For Technology And Research-2017
Mix Design of High Strength Concrete by Partially Replacement of Cement by Flyash T.Divya Sree1,K.Srinivasa Rao2 1
U.G Student,2Asst. Professor,
, Department of Civil Engineering,
Sir C R R College of Engineering, Eluru,India
Abstract: Concrete is the commonly used material which is mostly used in civil engineering structures. The present investigation deals with high strength concrete of M60 by partial replacement of OPC with fly ash in percentages of 0%, 5%, 10% and 15% in various ratios and also add Masterpel 777 super plasticizer for workability purpose. After completion of experiment we have to do the compressive, Flexure and split tensile strength tests during the periods of 7,14 and 28 days. In this design project we have designed M60 grade concrete using Department of Environment (DOE) mix design method.
FLYASH: Fly ash is the ash particle resulting from the combustion of pulverised coal. These ash are collected by using electric precipitators. When compared to the fly ash, cement have high heat of hydration so some thermal cracks are produced by using cement in the concrete mixture. So the fly ash is replaced by cement to increase the strength of building and prevent the thermal cracks. The addition of fly ash has effects on many properties such as workability hydration, shrinkage, heat evolution & durability.
Keywords: High strength concrete, Fly ash, super plasticizer, DOE method. PROPERTIES OF FLYASH:
1. INTRODUCTION
Physical properties of fly ash
Concrete is made by the mixture of cement, fine aggregate, coarse aggregate and water. Strength of concrete varies depending up on the addition of water into the mixture of concrete. Using the dry Portland cement for preparing the concrete then the mixture forms a fluid slurry that can be easily poured and moulded into shape. The cement reacts chemically with the water and other ingredients to form a hard, durable stone like material such as lime based concretes are used like Portland cement concrete. Concrete is the basic building material which is widely used for many kinds of structures. Now-a-days number of structures have been designed and constructed. In this mainly High Strength concrete (HSC) are used. High strength Concrete provides economic benefits through thinner construction. If a concrete having compressive strength of greater than or equal to 41 MPA then that concrete is called High Strength Concrete (HSC).
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PARAMETERS
FLYASH
Bulk Density (gm/cc)
0.9 - 1.3
specific Gravity
1.6-2.6
Plasticity
Lower or non-plasticity
Shrinkage limit (vol stability)
Higher
Grain size
Major fine sand / silt and small per cent of clay size particles
Clay (percent)
Negligible
Free Swell Index
Very low
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IDL - International Digital Library Of Technology & Research Volume 1, Issue 5, May 2017
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International e-Journal For Technology And Research-2017 Classification (Texture)
Sandy silt to silty loam
Water Holding (WHC) (percent)
capacity 40-60
Porosity (percent)
30-65
Surface Area (m2/kg)
500-5000
Lime reactivity (Mpa)
1-8
MasterPel 777 can be used for any type of construction. Additionally, it can be used in concrete applications constantly or intermittently in contact with water such as sea walls, tunnels, basements, structural and pre-cast concrete in exposed superstructures. Points to remember when producing waterproof concrete: • Ensure w/c ratio is in the range of 0.40 to 0.60. • Keep water content as low as possible.
ADVANTAGES: ● ● ● ● ● ● ●
Fly ash is a economical and environmentally friendly solution. It gives good workability, durability, smooth and soft surface of finishing. It has highly dense and reduces the permeability of concrete. Cost of fly ash is less when compared to the cement. It prevent the thermal cracks and gives high strength of building. It is also helpful in reducing the heat of hydration. Shrinkage of fly ash is less & it prevent the acid Sulphate attacks.
DISADVANTAGES: ● ●
OBJECTIVES OF STUDY The objectives of study are as follows:
To study the optimum percentage composition of fly ash replacing cement which does not affect the concrete strength. To determine the compressive strength, flexural strength, split tensile strength of concrete replaced with different percentages of fly ash with cement. To study the durability aspects of concrete.
MATERIALS:
It increases the permeability. The quality of the fly ash is very poor and gives the negative impact on concrete and then it reduces the strength of structures.
MASTERPEL777 SUPERPLASTICIZER: MasterPel 777is liquid admixture designed to allow superior workability in concrete / mortar mixes with reduced water and also achieve high resistance to water ingress. It is based on a specially formulated polymers and compatible with all types of cement and binders (like fly ash, ground granulated slag, silica fume, metakaolin etc.). Uses:
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• Place concrete quickly and compact it well.
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The various materials used in the concrete mix proportion is explained as follows.
CEMENT: Cement is a binding material used to bind the sand and gravel together and it is mainly used for construction purpose.
TESTS ON CEMENT: The following tests are commonly performed in laboratory to know the properties of materials which are used in the concrete. According to their relevant IS codes they had done the cement tests of fineness of cement. Normal consistency of cement, Initial and Final setting time of cement, Specific gravity of cement, Compressive strength of cement. Copyright@IDL-2017
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International e-Journal For Technology And Research-2017 summarized in Tables below. Each value is the mean of a three test result. The capacity of compression machine They are two types of aggregates fine aggregate and coarse is TESTS ON AGGREGATE:
aggregate. According to their relevant IS codes they had done the tests on fineness modulus of fine aggregate, Specific đ?‘´đ?’‚đ?’™.đ?‘łđ?’?đ?’‚đ?’… Compressive Strength = = đ?‘¨đ?’“đ?’†đ?’‚ gravity of fine aggregate, Bulk density of sand, Bulking of sand and fineness modulus of coarse aggregate, Specific gravity of coarse aggregate, Bulk density of coarse aggregate
TEST
Cement
� �
RESULT
Fineness of cement
5%
Normal consistency
32%
Initial setting time
51 min
Final setting time
519 min
Specific gravity
3.12
Compressive strength of cement Fineness modulus Fine Aggregate of FA Specific gravity of (FA)
58.14 N/mm2 3.18 Fig.1: Compression Testing Machine 2.47
FA Bulk sand
density
of
Bulking of sand
Fineness modulus Coarse Aggregate of CA Specific gravity of (CA)
1.580 gm/m3 48ml at 6% moisture content 6.98 2.63
CA Bulk density of CA
SPLIT TENSILE STRENGTH:
A total of 12 standard concrete cylinders of sizes 150 mm diameter and 300 mm height were tested for the indirect tensile strength. The test results are shown in below Tables. Each value represents the average of three test results. The split tensile strength was calculated according to BS1881: Part 4:1970 as follows:
1.32 kg/m3 Split tensile strength (fs) =
đ?&#x;?đ?‘ž đ??…đ?‘łđ?‘Ť
COMPRESSIVE STRENGTH
A total of 36 cube specimens of size 150 mm were tested for compression test. The test results are IDL - International Digital Library
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IDL - International Digital Library Of Technology & Research Volume 1, Issue 5, May 2017
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International e-Journal For Technology And Research-2017
Fig.2:Split Tensile Test
Fig.3:Flexural Testing Machine
Here, W = Maximum Load on Cylinder in KN L = Length of the Cylinder in mm D = Diameter of the Cylinder in mm A=Cross sectional area of cube in mm2
EXPERIMENTAL INVESTIGATION COMPRESSIVE STRENGTH OF CUBES:
A total of 12 beams of size 150 x 150 x 500 mm were tested for flexural strength. In all thetested specimen fracture occurred within the central one-third of the beam, hence according to BS1881: Part 4:1970, flexural strength (modulus of rupture) was calculated as follows: đ?‘žđ?‘ł
Flexure strength (fb) = đ?’ƒđ?’…đ?&#x;? Where, W = Maximum Load on Prism in KN L = Effective length of the Prism in mm b = Width of the prism in mm d = Depth of the Prism in mm
COMPRESSIVE STRENGTH N/mm2
FLEXURAL STRENGTH: 70
60 50
63.52 50.87 45.23 42.2
48.73 41.5
49.9
49.43 41.87
35.86
40
30.29
28.6
30
20 10 0 0
5
10
% OF FLY ASH 7 DAYS
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14 DAYS
28 DAYS
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2.6
2.53
FLEXURAL STRENGTH OF BEAMS:
2.48
2.5 2.35
2.4
2.31
2.3 2.2 0
5
10
15
% OF FLY ASH 28 DAYS
FLEXURAL STRENGTH N/mm2
SPLIT TENSILE STRENGTH N/mm2
SPLIT TENSILE STRENGTH OF CYLINDER:
4
3.5
3.81
3.59 3.33
3.2
3 2.5 0
5
10
15
s 28 DAYS
COMPRESSIVE STRENGTH OF CYLINDER N/mm2
COMPRESSIVE STRENGTH OF CYLINDERS:
40 30
25.3
29.7
34.5 24.6
DESIGN OF MIX FOR M60 GRADE CONCRETE: CONCRETE MIX DESIGN:
20 10
The grade of concrete, used in this study is M60. The mix
0
design is based on strength criteria and durability criteria
0
5
10
15
% OF FLY ASH
used for moderate environment. The ratios by weight of cement, fine aggregate and graded aggregate are obtained using the Department of Environment (DOE) method is
28 DAYS
given below. DOE method presently standard British method of concrete mix design. These proportions are maintained strictly same throughout the casting processto obtain a uniform standard and workable concrete mix. Cubes, Prisms, and Cylinders, were tested for compressive strength after28 days curing. The compressive, Split tensile and flexure tests are conducted. Workability tests are also done on the mix.
CONCLUSIONS:
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IDL - International Digital Library Of Technology & Research Volume 1, Issue 5, May 2017
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International e-Journal For Technology And Research-2017 To perform High strength self-compacting concrete
The following conclusions are drawn from the result of the investigation
for better workability in congest reinforcement. To check the various properties of concrete with
1.
The compressive, split tensile and flexural strength of all concrete specimens increased with age but decreasing phenomenon was observed with increase in the
4.
5.
6.
in concrete”, International Journal of Engineering
visible sign of deterioration after the 28-day immersion
Research, Volume -05 (2016), ISSN: 2319-6890, 2347-
period but rather show continuous improvement in
5013 8&9th Jan 2016. 2.
8.
Michael Thomas: “Optimizing the use of fly ash in
The compressive strength of concrete cubes at the rate of
concrete”, PhD, P.Eng, professor of Civil Engineering,
all days was optimum at 10% fly ash.
University of New Brunswick.
The split tensile strength of concrete cylinders at the rate 3.
P.Nath, P.Sarker: “Effect of fly ash on durability
of all days was optimum at 10% fly ash.
properties of High Strength Concrete”, the twelfth East
The compressive strength of concrete cylinders at the
Asia pacific conference on structural Engineering and
rate of all days was optimum at 10% fly ash.
construction, Procedia Engineering 14 (2011) 1149-
The flexural strength of concrete beams at the rate of all
1156. 4.
days was optimum at 10% fly ash. 7.
R.D.Pandhe, N.S.Deo: “Cement replacement by fly ash
The specimens immersed in water did not show any
strengths. 3.
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