Project on Concrete Mix Design for various grades of Concrete

Concrete Mix Design for M35 grade concrete with fly ash

AIM: Concrete Mix Design for M35 grade concrete with fly ash

PROCEDURE:

Step 1: Stipulations for Mix Design Concrete

1. Grade designation: M30
2. Type of cement: OPC 53 Grade conforming IS 8112
3. Type of mineral admixture: Fly ash confirming to IS 8112
4. Maximum nominal size of aggregate: 20mm
5. Minimum cement content: 320 kg/m³(Table 5 of IS 456:2000)
6. Maximum water-cement ratio: 0.45 (Table 5 of IS 456:2000)
7. Workability: 100-120mm slump
8. Exposure condition: Severe (For Reinforced Concrete)
9. Method of concrete placing: Pumping
10. Degree of supervision: Good
11. Type of aggregate: Crushed Angular Aggregates
12. Maximum cement content: 450 kg/m³
13. Chemical admixture type: Super Plasticizer

Step 2: TEST DATA FOR MATERIALS

a. Cement used: OPC 53 Grade

b. The specific gravity of cement: 3.15

c. The specific gravity of Fly ash: 2.2

d. Chemical admixture: Super Plasticizer conforming to IS 9103

e. Specific gravity of

Coarse aggregate: 2.74

Fine aggregate: 2.74

f. Water absorption:

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 all in aggregates of Table 2 of IS 383

Fine aggregate: Conforming to Grading Zone I of Table 4 of IS 383

Step 3: Calculation of Target Mean strength

f’ck =fck+1.65s

f’ck is the target average compressive strength

fck is the characteristic compressive strength, and

s is the standard deviation

From table 1 of IS 10262:2009, s=5 n/mm²

f’ck =fck+1.65s

= 35+(1.65*5)

= 43.25 N/mm²

Step 4: Selection of Water cement ratio

From table 5 of IS 456:2000 for severe exposure:

Maximum W/C ratio = 0.45

Adopted water cement ratio= 0.40

0.40<0.45 , Hence ok

Step 5: Calculation of water content:

From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 liters (for 25 to 50 mm slump range)

Estimated water content for 100 mm slump = 186+ (6/100*186) = 197 litre.

As Superplasticizer is used the water content can be reduced up to 20% and above.

Based on experience the water content reduction of 29% Is achieved using a superplasticizer

Hence the arrived water content = 197*0.71 = 140 litre.

Step 6: Calculation of cement content

Water cement ratio: 0.40

Cementatious material (Cement+fly ash) content = 140/0.4= 350 kg/m³

From Table 5 of IS 456, Minimum cement content for ‘severe’ exposure condition=320kg/m³
350 kg/m³ > 320 kg/m³, hence ok.

To proportion the mix containing fly ash the following steps are suggested:

1. The percentage of fly ash needs to be decided based on project requirements and the quality of materials.
2. In some cases, an increase in cementitious materials can be warned. An increase in cementitious material content and its percentage may be based on experience and trial

In this increase of 10%, cementitious material content is considered.

Cementatious material content= 350*1.1= 385 kg/mm³

Water content= 140 kg/mm³

So, water-cement ratio = 140/385 =0.364

Fly ash at 30% total cementatious material content = 35-30% = 115 kg/mm³

Cernent (OPC) = 385-115 = 270 kg/mm³

Saving of cement while using flyash = 350-270= 80 kg/mm³

Fly ash beign utilized = 115 kg/mm³

Step 7: Proportioning of coarse and fine aggregate content:

From Table 3 of IS 10262:2009, Volume of coarse aggregate corresponding to 20 mm size of coarse aggregate and fine aggregate (Zone I) for water-cement ratio =0.60.

In the present case, the water-cement ratio is 0.40.

Therefore the volume of coarse aggregate should be increased to decrease 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 water-cement ratio).

Therefore, the corrected proportion of the volume of coarse aggregate for the water-cement ratio of 0.40 = 0.64

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 – 0.56= 0.424.

Step 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)
= 270/3.15 x 1/1000
= 0.086 m³

c) Volume of fly ash = {[Mass of fly ash/Specific Gravity of fly ash]} x {1/1000}
= 115/2.2 x 1/1000
= 0.052 m³

d) Volume of water = {[Mass of water/Specific Gravity of water]} x {1/1000}
= 140/1 x 1/1000
= 0.140m³

e) Volume of chemical admixture = {[Mass of admixture/Specific Gravity of admixture]} x {1/1000}

= 7.6/1.145 x 1/1000
= 0.006m³

f) Volume of all aggregates (FA&CA) = [a-(b+c+d+e)]
= [1-(0.086+0.053+0.140+0.006)]
= 0.716 m³

g) Mass of coarse aggregate= f x Volume of Coarse Aggregate x Specific Gravity of Coarse Aggregate x 1000
= 0.716x 0.576 x 2.74 x 1000
= 1130 kg/m³

h) Mass of fine aggregate= f x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.716 x 0.424x 2.74 x 1000
= 831 kg/m³

Step 9: Mix proportions

Cement= 270 kg/m³

Water= 140 kg/m³

Fine Aggregate= 831 kg/m³

Coarse Aggregate = 1130 kg/m³

Chemical admixture= 7 kg/m³

Water cement ratio = 0.364

Trial Mix Ratio = 1:2.15:2.94

Step 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.

Step 11: Two more trials having variation of ± 10 percent of water-cement ratio in A-10 shall be carried out and a graph between three water-cement ratios and their corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials. However, the durability requirements shall be met.

RESULT: Concrete Mix Design for M35 grade concrete with fly ash is 1:2.15:2.94

Concrete Mix Design for M50 grade concrete

AIM: Concrete Mix Design for M50 grade concrete

PROCEDURE:

Step 1: Stipulations for Mix Design Concrete

1. Grade designation: M50
2. Type of cement: OPC 43 Grade conforming IS 8112
3. Type of mineral admixture: Fly ash confirming to IS 8112
4. Maximum nominal size of aggregate: 20mm
5. Minimum cement content: 320 kg/m³(Table 5 of IS 456:2000)
6. Maximum water-cement ratio: 0.45 (Table 5 of IS 456:2000)
7. Workability: 100-120mm slump
8. Exposure condition: Severe (For Reinforced Concrete)
9. Method of concrete placing: Pumping
10. Degree of supervision: Good
11. Type of aggregate: Crushed Angular Aggregates
12. Maximum cement content: 450 kg/m³
13. Chemical admixture type: Super Plasticizer

Step 2: TEST DATA FOR MATERIALS

1) Cement used: OPC 43 Grade

2) The specific gravity of cement: 3.15

3) Chemical admixture: Super Plasticizer conforming to IS 9103

4) Specific gravity of

Coarse aggregate: 2.74

Fine aggregate: 2.74

5) Water absorption:

Coarse aggregate: 0.5 %

Fine aggregate: 1.0 %

6) Free surface moisture:

Coarse aggregate: Nil

Fine aggregate: Nil

7) Sieve analysis:

Coarse aggregate: Conforming to all in aggregates of Table 2 of IS 383

Fine aggregate: Conforming to Grading Zone I of Table 4 of IS 383

Step 3: Calculation of Target Mean strength

f’ck =fck+1.65s

f’ck is the target average compressive strength

fck is the characteristic compressive strength, and

s is the standard deviation

From table 1 of IS 10262:2009, s=5 n/mm²

f’ck =fck+1.65s

= 50+(1.65*5)

= 58.25 N/mm²

Step 4: Selection of Water cement ratio

From table 5 of IS 456:2000 for severe exposure:

Maximum W/C ratio = 0.45

Adopted water cement ratio= 0.40

0.40<0.45 , Hence ok

Step 5: Calculation of water content:

From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 liters (for 25 to 50 mm slump range)

Estimated water content for 100 mm slump = 186+ (6/100*186) = 197 litre.

As Superplasticizer is used the water content can be reduced up to 20% and above.

Based on experience the water content reduction of 29% Is achieved using a superplasticizer

Hence the arrived water content = 197*0.71 = 140 litre.

Step 6: Calculation of cement content

Water cement ratio: 0.40

Cementatious material (Cement+fly ash) content = 140/0.4= 350 kg/m³

From Table 5 of IS 456, Minimum cement content for ‘severe’ exposure condition=320kg/m³
350 kg/m³ > 320 kg/m³, hence ok.

Step 7: Proportioning of coarse and fine aggregate content:

From Table 3 of IS 10262:2009, Volume of coarse aggregate corresponding to 20 mm size of coarse aggregate and fine aggregate (Zone I) for water-cement ratio =0.60.

In the present case, the water-cement ratio is 0.40.

Therefore the volume of coarse aggregate should be increased to decrease 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 water-cement ratio).

Therefore, the corrected proportion of the volume of coarse aggregate for the water-cement ratio of 0.40 = 0.64

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 – 0.56= 0.424.

Step 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)
= 350/3.15 x 1/1000
= 0.111m³

c) Volume of water = {[Mass of water/Specific Gravity of water]} x {1/1000}
= 140/1 x 1/1000
= 0.140m³

d) Volume of chemical admixture = {[Mass of admixture/Specific Gravity of admixture]} x {1/1000}

= 7.6/1.145 x 1/1000
= 0.006m³

e) Volume of all aggregates (FA&CA) = [a-(b+c+d)]
= [1-(0.111+0.140+0.006)]
= 0.743m³

f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Coarse Aggregate x 1000
= 0.743x 0.576 x 2.74 x 1000
= 1173 kg/m³

g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.743x 0.424x 2.74 x 1000
= 863 kg/m³

Step 9: Mix proportions

Cement= 350 kg/m³

Water= 140 kg/m³

Fine Aggregate= 863 kg/m³

Coarse aggregate = 1173 kg/m³

Chemical admixture= 7 kg/m³

Water cement ratio = 0.4

Trial Mix Ratio = 1:2.46:3.35

Step 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.

Step 11: Two more trials having variation of ± 10 percent of water-cement ratio in A-10 shall be carried out and a graph between three water-cement ratios and their corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials. However, the durability requirement shall be met.

RESULT: Concrete Mix Design for M50 grade concrete is 1:2.46:3.35