Project on Concrete Mix Design for various grades of Concrete
- Calculate the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash
Ans 1. A. Concrete Mix design for M 35 grade concrete with fly ash
- Stipulation for proportioning
- Grade designation M 35
- Type of Cement: OPC 43 grade conforming to IS 8112
- Type of Mineral admixture: Fly ash conforming to IS 3812 (Part 1)
- Maximum nominal size of aggregate: 20mm
- Minimum cement content: 320 kg/cum (From table 5 of IS 456: 2000- Exposure condition)
- Maximum water cement ratio: (From table 5 of IS 456: 2000- Exposure condition)
- Workability: 100 mm (slump for Pumpable concrete)
- Exposure: Severe (for reinforced concrete)
- Method of placing: Pumping
- Degree of Supervision: Good
- Type of aggregate: Crushed angular aggregate
- Chemical admixture type: Superplasticizer
- Test data of Materials
- Cement used: OPC 43 grade conforming to IS 8112
- Specific gravity of cement: 3.15
- Fly ash: Conforming to IS 3812 (Part 1)
- Specific gravity of fly ash: 2.2
- Chemical admixture: Super plasticizer conforming to IS 9103
- Specific gravity of aggregates
Coarse aggregate: 2.74
Fine aggregate: 2.74
- Water absorption of aggregates
Coarse aggregate: 0.5%
Fine aggregate: 1.0%
- Free surface moisture
Coarse aggregate: Nil
Fine aggregate: Nil
- Sieve Analysis
Coarse aggregate: Conforming to table 2 of IS 383
Fine aggregate: Conforming to Zone 1 of table 4 of IS 383
- Target Strength for Mix proportioning:
f’ck = fck +1.65 S
f’ck = target average compressive strength at 28 days
fck = Characteristic compressive strength at 28 days
S = standard deviation
From Table 1 of IS 10262: 2009 standard deviation, S= 5
Therefore, Target strength = 35+1.65 x5 =43.25
- Selection of Water cement ratio:
From Table 5 of IS 456: 2000 for severe exposure, maximum water cement ratio = 0.45
Adopt water cement ratio of 0.40 based on experience
0.40 <0.45 hence ok
- Selection of Water Content
From Table 2 of IS 10262: 2009, maximum water content for 20 mm aggregate= 186 litres (for slump range 25mm to 50mm)
Estimated water content for 100mm slump= 186 + (6/100) *186 =197 litres
As we are using superplasticizer water content can be reduced up to 30%
Based on trials water content reduction of 28% is achieved by plasticizer
The water content will be 197 x 0.72 = 141.84 litres say 142 litres
- Calculation of cement content
Water cement ratio = 0.40
Cementitious material (cement + fly ash) content = 142/0.40 = 355kg /cum
355kg > 320kg (minimum cement content as per Table 5 of IS 456 for severe exposure condition)
Based on experience and trials the cementitious material content is increased by 10 %
Therefore, total cementitious content = 355 x1.1 = 390 kg/cum
Water Content = 142 litres
So, Water Cement ratio = 142/390 = 0.364
Fly ash content @30% of total cementitious material= 390 x 0.3 = 117 kg/cum
Cement content = 390-117 = 273 kg/cum
Saving of Cement = 355-273= 82 kg/cum
Fly ash being used = 117 Kg/cum
- Proportion of Volume of Coarse aggregate and fine aggregate
From Table 3 of IS 10262:2009 Volume of coarse aggregate corresponding to coarse aggregate 20mm and fine aggregate (Zone 1) for water cement ration of 0.5 = 0.6
In present case the water cement ratio is 0.40
The volume of coarse aggregate needs to be increased to decrease the fine aggregate content.
As water content is less by 0.10 the volume of coarse aggregate needs to be increased by 0.02. ( +/-0.01 change for every +/-0.05 change in the water cement ratio)
Corrected volume of coarse aggregate for water cement ratio 0.40 =0.62
For pumpable concrete the coarse aggregate is reduced by 10%
Therefore, volume of coarse aggregate = 0.62 x 0.9 = 0.56
Volume of fine aggregate = 1-0.56 = 0.44
- Mix Calculations
Volume of concrete = 1 cum
Volume = (Mass/ Specific gravity) x1/1000
Volume of cement = (273/3.15) x 1/1000 = 0.087cum
Volume of fly ash = (117/2.2) x 1/1000 = 0.053cum
Volume of water = (142/1) x 1/1000 = 0.14cum
Volume of admixture = (7.6/1.145) x 1/1000 = 0.006cum
Volume of Aggregate (CA &FA) = 1-(0.087+0.053+0.14+0.006) = 0.714 cum
Mass of Coarse aggregate = 0.714 x 0.56 x2.74 x1000 = 1096kg
Mass of Fine aggregate = 0.714 x0.44 x 2.74 x1000 = 861kg
- Mix Proportions for M 35 grade concrete using Fly ash a. Cement = 273 kg/cumFly ash = 117 kg/cum b. Water = 142 kg/cum c.Fine aggregate = 861 kg/cum d. Coarse aggregate = 1096 kg/cum e. Chemical admixture = 7.4 kg/cum f. Water Cement ratio =0.364
Trial Mix Ratio = 1:2.21:2.81
B. Concrete Mix Design for M 50 grade concrete without Fly ash
- Stipulation for proportioning
- Grade designation M 50
- Type of Cement: OPC 43 grade conforming to IS 8112
- Maximum nominal size of aggregate: 20mm
- Minimum cement content: 320 kg/cum (From table 5 of IS 456: 2000- Exposure condition)
- Maximum water cement ratio: (From table 5 of IS 456: 2000- Exposure condition)
- Workability: 100 mm (slump for Pumpable concrete)
- Exposure: Severe (for reinforced concrete)
- Method of placing: Pumping
- Degree of Supervision: Good
- Type of aggregate: Crushed angular aggregate
- Chemical admixture type: Superplasticizer
- Test data of Materials
- Cement used: OPC 43 grade conforming to IS 8112
- Specific gravity of cement: 3.15
- Specific gravity of fly ash: 2.2
- Chemical admixture: Super plasticizer conforming to IS 9103
- Specific gravity of aggregates
Coarse aggregate: 2.74
Fine aggregate: 2.74
f. Water absorption of aggregates
Coarse aggregate: 0.5%
Fine aggregate: 1.0%
g.Free surface moisture
Coarse aggregate: Nil
Fine aggregate: Nil
h.Sieve Analysis
Coarse aggregate: Conforming to table 2 of IS 383
Fine aggregate: Conforming to Zone 1 of table 4 of IS 383
- Target Strength for Mix proportioning:
f’ck = fck +1.65 S
f’ck = target average compressive strength at 28 days
fck = Characteristic compressive strength at 28 days
S = standard deviation
From Table 1 of IS 10262: 2009 standard deviation, S= 5
Therefore, Target strength = 50+1.65 x5 =58.25
- Selection of Water cement ratio:
From Table 5 of IS 456: 2000 for severe exposure, maximum water cement ratio = 0.45
Adopt water cement ratio of 0.40 based on experience
0.40 <0.45 hence ok
- Selection of Water Content
From Table 2 of IS 10262: 2009, maximum water content for 20 mm aggregate= 186 litres (for slump range 25mm to 50mm)
Estimated water content for 100mm slump= 186 + (6/100) *186 =197 litres
As we are using superplasticizer water content can be reduced up to 30%
Based on trials water content reduction of 28% is achieved by plasticizer
The water content will be 197 x 0.72 = 141.84 litres say 142 litres
- Calculation of cement content
Water cement ratio = 0.40
Cementitious material (cement) content = 142/0.40 = 355kg /cum
355kg > 320kg (minimum cement content as per Table 5 of IS 456 for severe exposure condition)
Based on experience and trials the cementitious material content is increased by 10 %
Therefore, total cementitious content = 355 x1.1 = 390 kg/cum
Water Content = 142 litres
So, Water Cement ratio = 142/390 = 0.364
Cement content = 390 kg/cum
- Proportion of Volume of Coarse aggregate and fine aggregate
From Table 3 of IS 10262:2009 Volume of coarse aggregate corresponding to coarse aggregate 20mm and fine aggregate (Zone 1) for water cement ration of 0.5 = 0.6
In present case the water cement ratio is 0.40
The volume of coarse aggregate needs to be increased to decrease the fine aggregate content.
As water content is less by 0.10 the volume of coarse aggregate needs to be increased by 0.02. ( +/-0.01 change for every +/-0.05 change in the water cement ratio)
Corrected volume of coarse aggregate for water cement ratio 0.40 =0.62
For pumpable concrete the coarse aggregate is reduced by 10%
Therefore, volume of coarse aggregate = 0.62 x 0.9 = 0.56
Volume of fine aggregate = 1-0.56 = 0.44
- Mix Calculations
Volume of concrete = 1 cum
Volume = (Mass/ Specific gravity) x1/1000
Volume of cement = (390/3.15) x 1/1000 = 0.123cum
Volume of water = (142/1) x 1/1000 = 0.14cum
Volume of admixture = (7.6/1.145) x 1/1000 = 0.006cum
Volume of Aggregate (CA &FA) = 1-(0.123+0.14+0.006) = 0.731 cum
Mass of Coarse aggregate = 0.731 x 0.56 x2.74 x1000 = 1122kg
Mass of Fine aggregate = 0.731 x0.44 x 2.74 x1000 = 881kg a. Mix Proportions for M 50 grade concrete without Fly ash b. Cement = 390 kg/cum c. Water = 142 kg/cum d. Fine aggregate = 881 kg/cum e. Coarse aggregate = 1122 kg/cum f. Chemical admixture = 7.4 kg/cum g. Water Cement ratio =0.364
Trial Mix Ratio = 1:2.25:2.88