Project on Concrete Mix Design for various grades of Concrete
1. Mix design M35 Grade concrete with fly ash designed as per IS 10262:2009 & IS 456:2000
Mix proportioning for concrete of M35 grade concrete with fly ash is given in A·1 to A-11
A·1 STIPULATIONS FOR PROPORTIONING
a) Grade designation: M35
b) Type of cement: OPC 53 Grade conforming IS 12269
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 : 100-120mm slump
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 ECMAS HP 890
A-2 TEST DATA FOR MATERIALS
a) Cement used: OPC 53 Grade conforming IS 12269
b) Specific gravity of cement: 3.15
c) Chemical admixture: Super Plasticizer conforming to IS 9103 (ECMAS HP 890)
d) Specific gravity of fly ash:2.2
e) Specific gravity of
1) Coarse aggregate 20mm: 2.74
2) Fine aggregate: 2.74
f) Water absorption:
1) Coarse aggregate : 0.5 %
2) Fine aggregate (M.sand) : 1 %
g) Free (surface) moisture:
1) Coarse aggregate: Nil (Absorbed Moisture also Nil)
2) Fine aggregate: Nil
h) 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
A-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.
A-4 SELECTION OF WATER-CEMENT RATIO
Adopted maximum water-cement ratio = 0.44.
From Table 5 of IS 456 for Very severe Exposure maximum Water Cement Ratio is 0.45
0.44 < 0.45 Hence ok.
A-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 Superplasticizer is used, the water content can be reduced up to 20% and above.)
Based on trials with Superplasticizer water content reduction of 20% has been achieved, Hence the arrived water content = 197-[197 x (20/100)] = 158 liter.
A-6 CALCULATION OF CEMENT CONTENT
Adopted w/c Ratio = 0.44
Cement Content = 158/0.44 = 359 kg/m3
From Table 5 of IS 456, Minimum cement content for ‘Very severe’ exposure conditions 340kg/m3
= 359 kg/m3 > 340 kg/m3 hence ok.
The cementitious content has to be increased in order to attain good workability and strength. The increment required is determined on the basis of experience and research. Here we are increasing cementitious content by 10%.
Final cementitious content 359x1.10=395Kg
From Table 5 of IS 456, Minimum cement content for ‘Severe’ exposure conditions 320kg/m3
395 kg/m3 > 320 kg/m3 hence ok.
Cementitious material content =395
New water-cement ratio =158/395=0.4
Fly ash content is taken as 30% of total cementitious content =395x0.3 = 118.5kg/m3
Cement required =395-118 = 277kg/m3
A-7 PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponds to 20 mm size aggregate and fine aggregate (Zone II) for the water-cement ratio of 0.50 =0.62.
In the present case, the water-cement ratio is 0.44. Therefore, the volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.06. The proportion of the volume of coarse aggregate is increased by 0.02 (at the rate of -/+ 0.01 for every ± 0.05 change in water-cement ratio).
Therefore, the correct proportion of the volume of coarse aggregate for the water-cement ratio of 0.44 = 0.64
NOTE – In case the coarse aggregate is not angular, then also the volume of coarse aggregate may be required to be increased suitably based on experience & Site conditions.
For pumpable concrete, these values should be reduced up to 10%. Therefore, volume of coarse aggregate =0.64 x 0.9 =0.576.
Volume of fine aggregate content = 1 – 0.576= 0.424.
A-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}
= 277/{3.15 x 1000}
= 0.087 m3
c) Volume of fly ash = [Mass of fly ash] / {[Specific Gravity of fly ash] x 1000}
= 118/{2.2 x 1000}
= 0.053 m3
d) Volume of water = [Mass of water] / {[Specific Gravity of water] x 1000}
= 158/{1 x 1000}
= 0.158m3
e) Volume of chemical admixture = [Mass of chemical admixture] /{[Specific Gravity of chemical admixture ] x 1000}
= 7.6/{1.145x 1000}
= 0.006m3
f) Volume of all in aggregate = [a-(b+c+d+e)]
= [1-(0.087+0.053+0.158+0.006)]
= 0.696 m3
g) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.696 x 0.576 x 2.74 x 1000
= 1098 kg/m3
h) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.696 x 0.424 x 2.74 x 1000
= 808 kg/m3
A-9 MIX PROPORTIONS
Cement = 277 kg/m3
Fly ash= 118 kg/m3
Water = 158 l/m3
Fine aggregate = 808 kg/m3 Coarse aggregate 20mm = 1098 kg/m3
12mm = 220 kg/m3 (20% By Total weight of Coarse Aggregate)
Chemical admixture = 7.18 kg/m3 (0.4% by the weight of cement)
Density of concrete = 2512 kg/m3
Water-cement ratio = 0.40
Mix Proportion By weight = 1:2.04:2.78
NOTE – Aggregates should be used in saturated surface dry conditions. If otherwise, when computing the requirement of mixing water, the allowance shall be made for the free (surface) moisture contributed by the fine and coarse aggregates. On the other hand, if the aggregates are dry the amount of mixing water should be increased by an amount equal to the moisture likely to be absorbed by the aggregates. Necessary adjustments are also required to be made In the mass of aggregates. The surface water and percent water absorption of aggregates shall be determined according to IS 2386
A-10: The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump based on trial if required. The mix proportions shall be reworked for the actual water content and checked for durability requirements.
A-11: Two more trials having variation of 10% water-cement ratio shall be carried out and graph between three water-cement ratios and corresponding strength shall be plotted to work out the mix proportions for the given target for field trials.
2. Mix design M50 Grade concrete without fly ash designed as per IS 10262:2009 & IS 456:2000
Mix proportioning for concrete of M50 grade without fly ash is given in A·1 to A-11
A·1 STIPULATIONS FOR PROPORTIONING
a) Grade designation: M50
b) Type of cement: OPC 53 Grade conforming IS 12269
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 : 100-120mm slump
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( Polycarboxylate ether based)
A-2 TEST DATA FOR MATERIALS
a) Cement used: OPC 53 Grade conforming IS 12269
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: 2.65
f) Water absorption:
1) Coarse aggregate : 0.5 %
2) Fine aggregate (M.sand) : 1 %
g) Free (surface) moisture:
1) Coarse aggregate: Nil (Absorbed Moisture also Nil)
2) Fine aggregate: Nil
h) 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
A-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.
A-4 SELECTION OF WATER-CEMENT RATIO
Adopted maximum water-cement ratio = 0.44.
From Table 5 of IS 456 for Very severe Exposure maximum Water Cement Ratio is 0.45
0.44 < 0.45 Hence ok.
A-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 Superplasticizer is used, the water content can be reduced up to 20% and above.)
Based on trials with Superplasticizer water content reduction of 20% has been achieved, Hence the arrived water content = 197-[197 x (20/100)] = 158 liter.
A-6 CALCULATION OF CEMENT CONTENT
Adopted w/c Ratio = 0.44
Cement Content = 158/0.44 = 359 kg/m3
From Table 5 of IS 456, Minimum cement content for ‘Severe’ exposure conditions 320kg/m3
= 359 kg/m3 > 320 kg/m3 hence ok.
Cementitious material content =359 kg/m3
A-7 PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT
From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponds to 20 mm size aggregate and fine aggregate (Zone II) for the water-cement ratio of 0.50 =0.62.
In the present case, the water-cement ratio is 0.44. Therefore, the volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.06. The proportion of the volume of coarse aggregate is increased by 0.02 (at the rate of -/+ 0.01 for every ± 0.05 change in water-cement ratio).
Therefore, the correct proportion of the volume of coarse aggregate for the water-cement ratio of 0.44 = 0.64
NOTE – In case the coarse aggregate is not angular, then also the volume of coarse aggregate may be required to be increased suitably based on experience & Site conditions.
For pumpable concrete, these values should be reduced up to 10%. Therefore, volume of coarse aggregate =0.64 x 0.9 =0.576.
Volume of fine aggregate content = 1 – 0.576= 0.424.
A-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}
= 359/{3.15 x 1000}
= 0.114 m3
c) Volume of water = [Mass of water] / {[Specific Gravity of water] x 1000}
= 158/{1 x 1000}
= 0.158m3
d) Volume of chemical admixture = [Mass of chemical admixture] /{[Specific Gravity of chemical admixture ] x 1000}
= 7.6/{1.145x 1000}
= 0.006m3
e) Volume of all in aggregate = [a-(b+c+d)]
= [1-(0.114+0.158+0.006)]
= 0.722 m3
f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.722 x 0.576 x 2.74 x 1000
= 1139 kg/m3
g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.722 x 0.424 x 2.65 x 1000
= 811 kg/m3
A-9 MIX PROPORTIONS
Cement = 359 kg/m3
Water = 158 l/m3
Fine aggregate = 811 kg/m3 Coarse aggregate 20mm = 1139 kg/m3
Water-cement ratio = 0.40
Mix Proportion By weight = 1:2.25:3.17
NOTE – Aggregates should be used in saturated surface dry conditions. If otherwise, when computing the requirement of mixing water, the allowance shall be made for the free (surface) moisture contributed by the fine and coarse aggregates. On the other hand, if the aggregates are dry the amount of mixing water should be increased by an amount equal to the moisture likely to be absorbed by the aggregates. Necessary adjustments are also required to be made In the mass of aggregates. The surface water and percent water absorption of aggregates shall be determined according to IS 2386
A-10: The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump based on trial if required. The mix proportions shall be reworked for the actual water content and checked for durability requirements.
A-11: Two more trials having variation of 10% water-cement ratio shall be carried out and graph between three water-cement ratios and corresponding strength shall be plotted to work out the mix proportions for the given target for field trials.