Project on Concrete Mix Design for various grades of Concrete
1) The mix design for M35 grade concrete
Step(1):
- Target mean strength ft=fck+1.65*S
- From table 1 of IS 10262:2009
Standard deviation S= 5N/mm2
Ft= 35+1.65*5=43.25N/mm2
Step(2):
- Selection of water cement ratio - From table-5 of IS 456:2000, it can be taken depending upon the exposure condition.
- Max. Water cement ratio is 0.45
- Based on experience adopted water cement ratio is 0.40
- 0.40<0.45 hence ok
Step(3):
- Selection of water content - From table-2 of IS 10262-2009
- The max. Water content for 20mm to 50mm slump is 186kg=186lites
- Estimated water content for 100mm slump
- 186+6/100*186=197litres
As superplasticizers is used. The water content is reduced up to 20% and above
Hence the arrived water content =197*0.74=140litres
Step(4):
- Selection of cement content - it can be calculated from water cement ratio
- Min. Cement content is taken from table-5 of IS 456:2000
- W=140 litres
- C=140/0.4=350kg
Step(5):
- Mix calculations
A) volume of concrete =1m3
B) vol. Of Fly Ash =mass of fly Ash /specific gravity of fly Ash *1/1000=115/2.2*1/1000=0.052m3.
C) volume of cement =mass of cement /specific gravity of cement *1/1000
=350/3.15*1/1000
=0.111m3
D) volume of water =mass of water/specific gravity of water *1/1000
=140/1*1/1000
=0.140m3
E) Vol.of chemical admixture =mass of chemical admixer/specific gravity of chemical admixture *1/1000
=2.5/1.145*1/1000
=.0.006m3
F) volume of aggregates =(a-(b+c+d))
=(1-(0.111+0.140+0.006))
=0.743m3
G) mass of corse aggregate =e*vol. Of coarse aggregate *specific gravity of coarse aggregate *1000
=0.743*0.56*2.74*1000
=1140kg/m3
H)mass of fine aggregate =e*vol. Of fine aggregate *specific gravity of fine aggregate *1000
=0.743*0.44*2.74*1000=896kg/m3.
- Cement =350kg/m3
- Water=140kg/m3
- Fly Ash =0.052kg/m3
- Fine aggregate =896kg/m3
- Coarse aggregate =1140kg/m3
- Chemical adxmiture 0.006kg/m3
- Water cement ratio =0.4kg/m3
The mix ratio =1:2.56:3.26.
And M50 grade concrete without fly ash
Step(1):
- Target mean strength ft=fck+1.65 * S
- Ft =50+1.65*5=58.25N/mm2
Step(2):
- As per table 5 water cement ratio is 0. 40
- 0.40<0.45 hence ok
Step(3) :
- For 20mm slump water cement ratio is 186litres
- Estimated water content for 100mm slump is
- 186+6/100*186=197litres
- Hence superplasticizres are used then 30% water content is reduced then 197*0.7=140 litres
Step(4):
Cement content is
W/C =0.4=140/0.4=350kg/m3
Step(5):
Mix calculations :-
A) volume of concrete =1m3
B)volume of cement =350/3.15*1/1000=0.111m
C) volume of water =140/1*1/1000
=0.140m3
D) volume of chemical admixture =2.5/1.145*1/1000
=0.006kg/m3
E) volume of aggregate =(a-(b+c+d))
=(1-(0.111+0.145+0.006))
=0.743kg/m3
F) mass of coarse aggregate =e*volume of coarse aggregate *specific gravity of coarse aggregate *1000
=0.743*0.56*2.74*1000=1140kg/m3
G) mass of fine aggregate =0.743*0.44*2.74*1000=896kg/m3
Mix proportions
- Cement =360kg/m3
- Water=140kg/m3
- Fine aggregate =896kg/m3
- Coarse aggregate =1140kg/m3
- Chemical admixture =0.006kg/m3
- Water cement ratio =0.4kg/m3
The mix ratio =1:2.56:3.26.