Project on Concrete Mix Design for various grades of Concrete

• Design for M35 grade of concrete with fly ash:

1. STIPULATIONS FOR PROPORTIONING:

• grade ratio M35
• type of cement: OPC 43 grade conforming to IS 8112
• maximum nominal size of aggregate use 20mm
• workability of concrete 75mm slump for pump-able concrete
• exposure conditioners (RCC)
• type of crushed angular aggregate
• chemical admixture: super-plasticizer
• fly ash
• minimum cement content: 340kg/m^3 (IS 456:2000)
• maximum water-cement ratio: 0.45 (Table 5 of IS 456:2000)

2. TEST DATA FOR MATERIAL:

• cement used OPC 43 grade
• the specific gravity of cement: 3.15
• chemical admixture: superplasticizer
• the specific gravity of coarse aggregate and fine aggregate is 2.74
• water absorption: coarse aggregate is 0.5% and fine aggregate is 1%
• Sieve analysis conforming zone.

3. TARGET MEAN STRENGTH OF CONCRETE (F’CK)

f’ck= fck+1.65S

(Standard deviation value from IS10262:2009)

f’ck =35+1.65 X 5 =43.25 N/mm^2

4. SELECT FOR WATER-CEMENT RATIO:

(From table-5 IS456:200)

Maximum water-cement ratio =0.45

• from graph-1: to calculate the w/c ratio from graph code (compressive strength Vs w/c ratio graph). The value is 0.36
• From graph-2: To calculate the w/c ratio from graph 2, the A to F line indicates the 7-days compressive strength of cement and 28-days compressive strength of concrete (target mean strength). The value is 0.43.
• The smaller value is 0.36 so the water-cement ratio is 0.36 for the M35 grade of concrete.

5. SELECT OF WATER CONTENT:

(From table-2 IS10262:2009)

Minimum water content for (25-50)mm slump =186 Litter.

We are assuming an 80 mm slump then the adding 3% additional water

186 + (3/100)186 = 191.58 litters (for pump-able concrete)

Use of superplasticizer for reducing the water, the plasticizer can be reducing water up to 20%-30% we can assume 25% water can be reduced.

191.58 X 0.75 = 143.685 litter.

6. SELECTION OF CEMENT CONTENT:

(From table-5 of IS456:2000)

w/c=0.36

c=143.685/0.36 =399.125 kg/m^3

Minimum cement content is 340kg/^3 as per IS code and exposure condition and the maximum which is 450 kg/m^3 and the value is 399.125, hence ok.

The percentage of fly ash needs to be decided based on project requirement and quality of material, so we need some increase in the cementitious material. Increase in cementitious material by 10% assuming.

Cementitious material content =399.125 X 1.10 = 439 kg/m^3

Water content =143.685 kg/m^3

New Water cement ratio =143.685 / 439 = 0.327

Fly ash @ 30% total cementitious material content = 439 X 30% =131.7kg/m^3

Cement (OPC) =439-131.7 = 307.3 kg/m^3

7. VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE:

(From table-3 of IS10262:2009)

Selection depending upon the fine aggregate zone

Considered zone I which is 0.6

The value of the w/c ratio is less than 0.36 (the volume of increased coarse aggregate and decrease volume of fine aggregate).

As water cement ratio is lower by 0.1 the proportion of volume of coarse aggregate is increase by 0.02

The corrected volume of coarse aggregate for w/c=0.36=0.62

For pump-able concrete angular aggregate volumes are reduce by10%

Coarse aggregate=0.62 X 0.9=0.558 kg/m^3

Fine aggregate =1-.558=0.44 kg/m^3

8. DESIGN MIX CALCULATION

(a) Volume of concrete= 1m^3

(b) Volume of cement = mass of cement /s.gravity of cement x1000

307.3/3.15 X 1000 =0.101 m^3

(c)Volume of fly ash =131.7 /2.2 X 1000 = 0.05 kg / m^3

(d) Volume of water = 143.683/1 X 1000 = 0.143m^3

(e) Volume of chemical admixture = 7.6/1.145 X 1000 =0.006m^3

(f) Volume of total aggregate = a-(b+c+d+e)

1-(0.101+0.05+0.143+0.006) = 0.7 m^3

(g) Mass of coarse aggregate = f X volume of coarse aggregate X s.gravity X1000

0.7 X 0.558 X 2.74 X1000 =1070.244 kg/m^3

(h) Mass of fine aggregate = 0.7 X 0.44 X2.74 X 1000 = 843.92 kg/m^3

9. MIX PROPORTION

• Cement = 307.3kg/m^3
• Water =143.683 litter.
• Fine aggregate = 843.92kg/m^3
• Chemical admixture = 7 kg/m^3
• Water cement ratio = 0.327
• Fly ash = 131.7

Mix ratio = 1:2.74:3.48

• Design for M50 grade of concrete:
  1. STIPULATIONS FOR PROPORTIONING:
• Mix design M50
• type of cement: OPC 43 grade conforming to IS 8112
• maximum nominal size of aggregate use 20mm
• workability of concrete 100 mm slump for pump-able concrete
• exposure conditioners (RCC)
• type of crushed angular aggregate
• chemical admixture: super-plasticizer
  2. TEST DATA FOR MATERIAL:
• cement used OPC 43 grade
• specific gravity of cement: 3.15
• chemical admixture: superplasticizer
• specific gravity of coarse aggregate and fine aggregate is 2.74
• water absorption: coarse aggregate is 0.5% and fine aggregate is 1%
• Sieve analysis conforming zone.
  3. TARGET MEAN STRENGTH OF CONCRETE(C)

f’ck= fck+1.65S

(Standard deviation value from IS10262:2009)

f’ck =50+1.65 X 5 =58.25 N/mm^2

4. select for water-cement ratio:

(From table-5 IS456:200)

Maximum water cement ratio =0.45

From graph-2: To calculate the w/c ratio from graph 2, the A to F line indicates the 7-days compressive strength of cement and 28-days compressive strength of concrete (target mean strength). The value is 0.36.

4. SELECT OF WATER CONTENT:

(From table-2 IS10262:2009)

Maximum water content for (25-50) mm slump =186 Litter.

We are assuming a 150 mm slump then the adding 6% additional water

186 + (6/150)186 = 193.44 litters (for pump-able concrete)

Use of superplasticizer for reducing the water, the plasticizer can be reducing water up to 20%-30% we can assume 25% water can be reduced.

193.44 X 0.75 = 145.08 litter.

6. SELECTION OF CEMENT CONTENT:

(From table-5 of IS456:2000)

w/c=0.36

c=147.87/0.36 = 410.75 kg/m^3

Minimum cement content is 360kg/^3 as per IS code and exposure condition and maximum which is 450 kg/m^3 and the value is 410.75hence ok.

6. VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE:

(From table-3 of IS10262:2009)

Selection depending upon the fine aggregate zone

Considered zone I which is 0.6

The value of the w/c ratio is less than 0.36 (the volume of increased coarse aggregate and decrease volume of fine aggregate).

As water cement ratio is lower by 0.1 the proportion of volume of coarse aggregate is increase by 0.02

The corrected volume of coarse aggregate for w/c=0.36=0.62

For pump-able concrete angular aggregate volumes are reduce by10%

Coarse aggregate=0.62 X 0.9=0.558 kg/m^3

Fine aggregate =1-.558=0.44 kg/m^3

8. DESIGN MIX CALCULATION

(a) Volume of concrete= 1m^3

(b) Volume of cement = mass of cement /s.gravity of cement x1000

410.75/3.15 X 1000 =0.13m^3

(c) Volume of water = 147.87/1 X 1000 = 0.147m^3

(d) Volume of chemical admixture = 7.6/1.145 X 1000 =0.006m^3

(e) Volume of total aggregate = a-(b+c+d)

1-(0.13+0.147+0.006) = 0.663 m^3

(f) Mass of coarse aggregate = e X volume of coarse aggregate X s.gravity X1000

0.663 X 0.558 X 2.74 X1000 =1013.67 kg/m^3

(g) Mass of fine aggregate = 0.663 X 0.44 X2.74 X 1000 = 802.23 kg/m^3

9. MIX PROPORTION

• Cement = 410.75kg/m^3
• Water =147.87 litter.
• Fine aggregate = 802.23kg/m^3
• Coarse aggregate = 1013.67
• Chemical admixture = 7 kg/m^3
• Water cement ratio = 0.36

Mix ratio = 1:1.95:2.46