Project on Concrete Mix Design for various grades of Concrete
Mix Design for M35 Grade Concrete
Aim
The mix design for M35 grade of concrete with fly ash will be calculated and ratio will be obtained.
Procedure
Step 1 : Stipulations for proportioning
1. Grade designation : M35
2. Type of cement: OPC 53 grade conforming to IS 8112
3. Type of mineral admixture: Fly ash confirming to IS 3812
4. Maximum nominal size of aggregates : 20mm
5. Minimum cement content : 320 kg/m^3 ( IS 456-2000)
6. Maximum water-cement ratio : 0.45 ( IS 456 - 2000)
7. Workability :100mm slump value of pumpable concrete
8. Exposure condition: Severe (for reinforced concrete)
9. Method of concrete placing : Pumping
10. Degree of supervision: Good
11. Type of aggregate: Crushed angular aggregate
12. Maximum cement content: 450 kg/m^3.
13. Chemical admixture type : Superplaticizer.
Step 2 : Test data of materials
1. Cement grade : OPC 53
2. Specific gravity of cement : 3.15
3. Specific gravity of coarse aggregate ; 2.74
4. Specific gravity of fine aggregate : 2.74
5. Water absorption of coarse aggregate : 0.5%
6. Water absorption of fine aggregate : 1%
Step 3 : Target mean strength
Target mean strength , Fck = fck + 1.65s = 35 + 1.65 x 5 = 43.25 N/mm^2
fck - compressive strength
s - standard deviation
Step 4 : Selection of water cement ratio
Maximum water cement ratio : 0.45 ( Table 5 - IS 456)
Adopted water cement ratio : 0.40
Step 5 : Selection of water content
Maximum water content = 186 L (25 to 50mm slump)
For 100mm slump = 186 + (6/100) x186 = 197 L
If superplasticizer is used , the water content is reduced up to 20%
Based on trials water content reduction of 29% is achieved with superplasticizer
Hence, water content = 197 x 0.71 = 140 L
Step 6 : Selection of cement content
Water cement ratio = 0.40
Cement content = 140/0.40 = 350 kg/m^3
Cement content for severe exposure is 320 kg/m^3
350 kg/m^3 > 320 kg/m^3
Hence, OK
For the proportioning the mix containing fly ash,
Increase in 10% of cementatious material
= 350 x 1.1 = 385 kg/m^3
Water content = 140
Water cement ratio = 140/385 = 0.364
Fly ash of 30 % in total = 385 x30% = 115
Cement = 385 - 115 = 270 kg/m^3
Saving of cement while using fly ash = 350 - 270 = 80 kg
Fly ash utilized = 115 kg/m^3
Step 7 : Voume of proportioning of coarse and fine aggregate
From Table 3 of IS 10262, volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for a 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 is required to be increased to reduce the fine aggregate content.
As the water-cement ratio is lower by 0.10, 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 the water-cement ratio). Therefore. the corrected proportion of the volume of coarse aggregate for the water-cement ratio of 0.45 = 0.63.
For pumpable concrete, these values should be reduced by 10 percent.
Therefore, vol of coarse aggregate = 0.64 x 0.9 = 0.576
Volume of fine aggregate content = 1 – 0.576 = 0.424
Step 8 : Mix calculation
1. Volume of concrete = 1m^3
2. Volume of cement = ((mass of cement/specific gravity of cement) x 1/1000) = ((270/3.15) x 1/1000) = 0.086 m^3
3. Volume of water = ( 140/1 x 1/1000) = 0.140 m^3
4. Volume of fly ash = ( 115/2.2 x 1/1000) = 0.052 m^3
4. Volume of superplasticizer = ((7/1.145) x 1/1000) = 0.006 m^3
5. Volume of all aggregate = 1 - (0.086 + 0.140 +0.052+ 0.006) = 0.716 m^3
6. Mass of coarse aggregate =( vol of all aggregate x vol of coarse aggregate x specific gravity of coarse aggregate x 1000 ) = 0.716 x 0.576 x 2.74 x 1000 = 1130 kg
7. Mass of fine aggregate = ( vol of all aggregate x vol of fine aggregate x specific gravity of fine aggregate x 1000 ) = 0.716 x 0.424 x 2.74 x 1000 = 831 kg
Step 9 : Mix proportions
- Cement = 270 kg/m^3
- Water = 140 L
- Fly ash = 115 kg/m^3
- Superplasticizer = 7 kg/m^3
- Fine aggregate = 831 kg/m^3
- Coarse aggregate = 1130 kg/m^3
- Water cement ratio = 0.40
Mix ratio obtained
The mix ratio for M35 grade concrete is 1 : 2.15 : 2.94 (Cement : Fine aggregate : Coarse aggregate).
Result
This is the mix design for M35 grade of concrete and the obtained mix ratio is 1 : 2.15 : 2.94.
Mix Design for M50 Grade Concrete
Aim
The mix design for M50 grade of concrete without fly ash will be calculated and ratio will be obtained.
Procedure
Step 1 : Stipulations for proportioning
1. Grade designation : M50
2. Type of cement: OPC 53 grade conforming to IS 8112
3. Maximum nominal size of aggregates : 20mm
4. Minimum cement content : 320 kg/m^3 ( IS 456-2000)
5. Maximum water-cement ratio : 0.45 ( IS 456 - 2000)
6. Workability :100mm slump value of pumpable concrete
7. Exposure condition: Severe (for reinforced concrete)
8. Method of concrete placing : Pumping
9. Degree of supervision: Good
10. Type of aggregate: Crushed angular aggregate
11. Maximum cement content: 450 kg/m^3.
12. Chemical admixture type : Superplaticizer.
Step 2 : Test data of materials .
1. Cement grade : OPC 53
2. Specific gravity of cement : 3.15
3. Specific gravity of coarse aggregate ; 2.74
4. Specific gravity of fine aggregate : 2.74
5. Water absorption of coarse aggregate : 0.5%
6. Water absorption of fine aggregate : 1%
Step 3 : Target mean strength
Target mean strength , Fck = fck + 1.65s = 50 + 1.65 x 5 = 58.25 N/mm^2
fck - compressive strength
s - standard deviation
Step 4 : Selection of water cement ratio
Maximum water cement ratio : 0.45 ( Table 5 - IS 456)
Adopted water cement ratio : 0.40
Step 5 : Selection of water content
Maximum water content = 186 L (25 to 50mm slump)
For 100mm slump = 186 + (6/100) x186 = 197 L
If superplasticizer is used , the water content is reduced up to 20%
Based on trials water content reduction of 29% is achieved with superplasticizer
Hence, water content = 197 x 0.71 = 140 L
Step 6 : Selection of cement content
Water cement ratio = 0.40
Cement content = 140/0.40= 350 kg/m^3
Cement content for severe exposure is 320 kg/m^3
350 kg/m^3 > 320 kg/m^3
Hence, OK
Step 7 : Voume of proportioning of coarse and fine aggregate
From Table 3 of IS 10262, volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for a 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 is required to be increased to reduce the fine aggregate content.
As the water-cement ratio is lower by 0.10, 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 the water-cement ratio). Therefore. the corrected proportion of the volume of coarse aggregate for the water-cement ratio of 0.45 = 0.63.
For pumpable concrete, these values should be reduced by 10 percent.
Therefore, vol of coarse aggregate = 0.64 x 0.9 = 0.576
Volume of fine aggregate content = 1 – 0.576 = 0.424
Step 8 : Mix calculation
1. Volume of concrete = 1m^3
2. Volume of cement = ((mass of cement/specific gravity of cement) x 1/1000) = ((350/3.15) x 1/1000) = 0.111 m^3
3. Volume of water = ( 140/1 x 1/1000) = 0.140 m^3
4. Volume of superplasticizer = ((7/1.145) x 1/1000) = 0.006 m^3
5. Volume of all aggregate = 1 - (0.111 + 0.140 + 0.006) = 0.743 m^3
6. Mass of coarse aggregate =( vol of all aggregate x vol of coarse aggregate x specific gravity of coarse aggregate x 1000 ) = 0.743 x 0.576 x 2.74 x 1000 = 1173 kg
7. Mass of fine aggregate = ( vol of all aggregate x vol of fine aggregate x specific gravity of fine aggregate x 1000 ) = 0.743 x 0.424 x 2.74 x 1000 = 863 kg
Step 9 : Mix proportions
Cement = 350 kg/m^3
Water = 140 L
Superplasticizer = 7 kg/m^3
Fine aggregate = 863 kg/m^3
Coarse aggregate = 1173 kg/m^3
Water cement ratio = 0.40
Mix ratio obtained
The mix ratio for M50 grade concrete is 1 : 2.46 : 3.35 (Cement : Fine aggregate : Coarse aggregate).
Result
This is the mix design for M50 grade of concrete and the obtained mix ratio is 1 : 2.46 : 3.35.