Project on Concrete Mix Design for various grades of Concrete
The concrete mix design for M35 grade concrete with Fly ash.
- Grade designation : M35
- Type of cement : OPC 53 Grade conforming IS 12269
- Maximum nominal size of aggregate : 20mm
- Minimum cement content : 320 kg/m3 (IS 456:2000)
- Maximum cement content : 450kg/m3
- Maximum water-cement ratio : 0.45 (Table 5 of IS 456:2000
- Partial replacement of cement by Fly ash : 30% (as per requirement)
- Workability : 100-120mm slump
- Exposure condition : Severe’ exposure(For Reinforced Concrete)
- Method of concrete placing : Pumping
- Degree of supervision : Good
- Type of aggregate : Crushed Angular Aggregates
- Maximum cement content : 360 kg/m3
- Chemical admixture type : Super Plasticizer
2 TEST DATA FOR MATERIALS
a) Cement used : OPC 53 Grade conforming IS 12269
b) Specific gravity of cement : 3.15
c) Specific Gravity of Fly ash : 2.90
D) Chemical admixture : Super Plasticizer conforming to IS 9103
E) Specific gravity of
1) Coarse aggregate 20mm : 2.75
2) Fine aggregate : 2.75
e) Water absorption:
1) Coarse aggregate : 0.5 %
2) Fine aggregate : 1.0 %
f) Free (surface) moisture:
1) Coarse aggregate : Nil (Absorbed Moisture also Nil)
2) Fine aggregate : Nil
g) Sieve analysis:
1) Coarse aggregate: Conforming to all in aggregates of Table 2 of IS 383
2) Fine aggregate : Conforming to Grading Zone II of Table 4 of IS 383
3 TARGET STRENGTH FOR MIX PROPORTIONING
f’ck =fck + 1.65 s
where
f’ck = target average compressive strength at 28 days,
fck = characteristics compressive strength at 28 days, and
s = standard deviation.
From Table I of IS 10262:2009, Standard Deviation, s = 5 N/mm2. Therefore, target strength = 35 + 1.65 x 5 = 43.25 N/mm2.
4 SELECTION OF WATER•CEMENT RATIO
Adopted maximum water-cement ratio = 0.45. From the Table 5 of IS 456 for Very severe Exposure maximum Water Cement Ratio is 0.45 0.45 < 0.45 Hence ok.
5 SELECTION OF WATER CONTENT
From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 litre (for 25 to 50 mm slump range) Estimated water content for 100 mm slump = 186+ (6/186) = 197 litre.
(Note: If Super plasticizer is used, the water content can be reduced upto 20% and above.)
Based on trials with Super plasticizer water content reduction of 20% has been achieved, Hence the arrived water content = 197-[197 x (20/100)] = 159.9litre.
6 CALCULATION OF CEMENT CONTENT
Adopted w/c Ratio = 0.45
Total Cementitious (Cement +Fly ash) requirement = Water Content / WaterCement ratio
=160/0.45
= 355.55kg
From Table IS 456 minimum cement content for Sever exposure condition= 320kg/m3
355.55kg/m3 = 320kg/m3 hence ok
Since flying ash is used, the amount of cementitious content (cement + fly ash) should be increased to get good performance and strength. The percentage of increasing cementitious content depends on experience and research. Here we have increased the cementitious content by 10%.
Cementitious material content = 356*1.10
=391.6kg
Minimum Cement Content
required for ‘severe’ exposure = 340kg (Table 5-IS456)
Adopted Cementious content = 391.6 kg > 340kg
So water cement ratio = 160/391.6
= 0.409
Fly ash @ 30% total Cementitios = 391.6*0.30 (30% replacement)
= 117.48= 118kg/m^3
Cement content requirement = Cement content - Fly ash
= 391.6 - 117.48
= 274.12kg/m^3
Saving of Cement while usig = 356- 274
= 109kg/m^3
Calculation of Super Plasticiers @ 0.6 percent to the mass of cementitious content = = 391.6*(0.6/100) = 2.35 kg
7 PROPORTIO0N OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 =0.62
In the present case the water cement ratio is 0.45
Therefore, the volume of coarse aggregate needs to be increased to decereses the fine aggregate content
As water-cement ratio is lower by 0.10 the proportion of vol of coare agg is increased by 0.02(at the rate of -/+ 0.01 for every +/-0.05change in water-cement ratio)
Therefore , corrected volume of coarse aggregate for the water-cement ratio of 0.45=0.63
For pumpable concrete there values are reduced by 10%
Therefore volume of corse agg
0.63*0.63 = 0.567
Volume of fine aggregate content
1-0.567 = 0.433
.
8 MIX CALCULATIONS
The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete = 1 m3
b) Volume of cement = [Mass of cement] / {[Specific Gravity of Cement] x 1000}
= 275/{3.15 x 1000}
= 0.087m3
C) Total Volume of Fly ash = Flyash/(S.G*1000)
= 118/(2.5*1000)
= 0.041 m3
d) Volume of water = [Mass of water] / {[Specific Gravity of water] x 1000}
= 160/{1 x 1000}
= 0.160m3
e) Volume of chemical admixture = 2.35/(1.12*1000) (By Trial and Error Method used 0.4% by the weight cement)
f) Volume of all in aggregate = [a-(b+c+d+e)]
= [1-(0.087+0.04+0.160+0.002)]
= =0.71 kg/m3
g) Mass of coarse aggregate= f x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.71x0.567 x 2.74 x 1000
= 1103.04 kg/m3
h) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.71x 0.433x 2.74 x 1000
= 861.81 kg/m3
MIX PROPORTIONS
Cement = 275kg/m3
Fly ash = 118kg/m3
Water = 160 l/m3
Fine aggregate = 861.81 kg/m3 Coarse aggregate 20mm = 882 kg/m3
Coarse Aggregate (20mm) = 1103.04 kg/m3
Chemical admixture = 1.34 kg/m3 (0.4% by the weight of cement)
Density of concrete = 2430 kg/m3
Water-cement ratio = 0.45
To find the design mix ratio, divide the calculated value of all materials by the weight of cement. Therefore Mix Ratio of M35 Grade concrete by weight is Cement : Flyash: F.A : C.A : Water = 1:0.4:2.6:4.46:0.58
Ans. 2
The concrete mix design for M50 grade concrete.
The concrete mix design for M40 grade concrete.
a) Grade designation : M50
b) Type of cement : OPC 43 Grade conforming IS 8112
c) Maximum nominal size of aggregate : 20mm
d) Minimum cement content : 320 kg/m3 (IS 456:2000)
e) Maximum water-cement ratio : 0.45 (Table 5 of IS 456:2000)
f) Workability : 100mm (slump value for pumpable concrete)
g) Exposure condition : Severe(For Reinforced Concrete)
h) Method of concrete placing : Pumping
j) Degree of supervision : Good
k) Type of aggregate : Crushed Angular Aggregates
m) Maximum cement content : 450 kg/m3
n) Chemical admixture type : Super Plasticizer
2 TEST DATA FOR MATERIALS
a) Cement used : OPC 43 Grade conforming IS 8112
b) Specific gravity of cement : 3.15
c) Chemical admixture : Super Plasticizer conforming to IS 9103
d) Specific gravity of
1) Coarse aggregate 20mm : 2.74
2) Fine aggregate : 2.74
e) Water absorption:
1) Coarse aggregate : 0.5 %
2) Fine aggregate (M.sand) : 1.0%
f) Free (surface) moisture:
1) Coarse aggregate : Nil (Absorbed Moisture also Nil)
2) Fine aggregate : Nil
g) Sieve analysis:
1) Coarse aggregate: Conforming to all in aggregates of Table 2 of IS 383
2) Fine aggregate : Conforming to Grading Zone I of Table 4 of IS 383
3 TARGET STRENGTH FOR MIX PROPORTIONING
f’ck =fck + 1.65 s
where
f’ck = target average compressive strength at 28 days,
fck = characteristics compressive strength at 28 days, and
s = standard deviation.
From Table I of IS 10262:2009, Standard Deviation, s = 5 N/mm2. Therefore, target strength = 50 + 1.65 x 5 = 58.25 N/mm2.
4 SELECTION OF WATER•CEMENT RATIO
Adopted maximum water-cement ratio = 0.45. From the Table 5 of IS 456 for Very Severe Exposure maximum Water Cement Ratio is 0.45.
0.40 < 0.45 Hence ok.
5 SELECTION OF WATER CONTENT
From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 litre (for 25 to 50 mm slump range) Estimated water content for 100 mm slump = 186+ (6/186) = 197 litre.
(Note: If Super plasticizer is used, the water content can be reduced upto 20% and above.)
Based on trials with Super plasticizer water content reduction of 20% has been achieved, Hence the arrived water content = 197-[197 x (20/100)] = 157.4 litre.
6 CALCULATION OF CEMENT CONTENT
Adopted w/c Ratio = 0.45
Cement Content = 157.6/0.45 = 350.2 kg/m3
From Table 5 of IS 456, Minimum cement content for ‘Sever’ exposure conditions 320kg/m3
= 350.2kg/m3 > 320 kg/m3 hence ok
7 PROPORTIO0N OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone I) for water-cement ratio of 0.50 =0.6.
In the present case the water cement ratio is 0.45
Therefore, the volume of coarse aggregate needs to be increased to decereses the fine aggregate content
As water-cement ratio is lower by 0.10 the proportion of vol of coare agg is increased by 0.02(at the rate of -/+ 0.01 for every +/-0.05change in water-cement ratio)
Therefore , corrected volume of coarse aggregate for the water-cement ratio of 0.45=0.61
For pumpable concrete there values are reduced by 10%
Therefore volume of corse agg
0.61*0.9 = 0.549
Volume of fine aggregate content
1-0.549 = 0.451
8 MIX CALCULATIONS
The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete = 1 m3
b) Volume of cement = [Mass of cement] / {[Specific Gravity of Cement] x 1000}
= 350.2/{3.15 x 1000}
= 0.111m3
c) Volume of water = [Mass of water] / {[Specific Gravity of water] x 1000}
= 157.4/{1 x 1000}
= 0.1574m3
d) Volume of chemical admixture = 0.006 litres/ m3 (By Trial and Error Method used 0.4% by the weight cement)
e) Volume of all in aggregate = [a-(b+c+d)]
= [1-(0.111+0.157+0.006)]
= 0.725m3
f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.725x 0.549x 2.74 x 1000
= 1091 kg/m3
g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.725x 0.451x 2.74 x 1000
= 896/m3
9 MIX PROPORTIONS
Cement = 350 kg/m3
Water = 157 l/m3
Fine aggregate = 896 kg/m3
Coarse aggregate 20mm = 1091 kg/m3
Chemical admixture = 7kg/ m3 (0.4% by the weight of cement)
Water-cement ratio = 0.45
M50 Mix Proportion By weight = 1:2.56:3.11