Project on Concrete Mix Design for various grades of Concrete
Aim :To calculate the concrete mix desing for M35 grade concrete with fly ash
EQUATIONS :Target mean strength :f ck=fck+1.65s
fck=target mean
strength
fck=compressive
strength at 28 days of concrete
s= standard
deviation (IS 10262:2009,table-1)
*volume of cement:(mass of cement /specific gravity of cement).1/1000
*volume of water:(mass of water/specific gravity of water).1/1000
*volume of chemical admixtures:(mass of chemical admixture /specific gravity of chemical admixture).1/1000
*volume of fly ash:(mass of fly ash/specific gravity of fly ash).1/1000
*volume of concrete:1m^3
*volume of aggregates:(volume of concrete-(volume of cement+volume of fly ash+volume of water+volume of admixture)
*Mass of coarse aggregates :volume of aggregates.volume of coarse aggregate.specific gravity of coarse aggregate.100
*Mass of fine aggregate:volume of aggregate.volume of fine aggregate .specific gravity oh fine aggregates.1000
CODES FOR CONCRETE MIX DESIGN:
*IS 10262:2009
*IS 456:2000
*IS 8112
*IS 9103
*IS 3812(PART 1)
OBJECTIVES:
*The main objective is to produce concrete as economically as possible
*To achieve desired workability ,durability and minimum strength of M35 grade concrete .
procedure and calculatons:
1.Target mean strength
F`ck=fck+1.65 5
fck=35N/mm^2(M35)
s=5 N/mm^2
f`ck=35+(1.65.5)
43.25N/mm^2
2.SELECTION OF WATER CEMENT RATIO:
GIVEN:
M35
ASSUME:
expouser condition:Extream (for reinforced concrete)
TABLE 5-IS 456:2000
therefore`
Extream=w/c ratio=0.40
M35=w/c ratio=0.45
lower the water cement ratio better the workability
0.40<0.45
water cement ratio =0.40
minimum cement content=360kg/m^3
3.SELECTION OF WATER CONTENT
Assume:
Nominal size of aggregates=20mm
Minimum water content =186 litres or kg
slump ranges from 25 to 50mm
as superplastisizers (20% reduced)=186.80/100=148.8(100-20=80)
water content =149 litres
4.CALCULATION OF CEMITITOUS CONTENT(CEMENT+FLY ASH)
Water cement ratio=w/c=0.40
water content =w=149kg
cementitous content =c=149/0.kg/40=372.5=370kg/m^3
increased by 10%
370.0.10+370=407 kg/m^3
w=149kg
water cement ratio=149/407=0.366
fly ash at 30%total cemeentitious material content =407.30/100=122kg/m^3
cement(ordinary portland cement )=407-122=285kg/m^3
saving of cement while using fly ash =370-285=85kg/m^3
Fly ash=122kg/m^3
5.volume of coarse aggregates and fine aggregates
Fine aggregates are sieved according to Zone 1 of table 4 IS 383
coarse aggregates are sieved according to table 2 IS 383
According ,
table 3 IS 10262:2009
Norminal size of aggregates =20mm
fine aggregates (zone 1)
therefore,
volume of coarse aggregates=0.60
water cement ratio=0.4
so,volume of coarse aggrwgates =0.62
volume of fine agggregate =1-0.62=0.38
RESULT AND CONCLUSION:
TRAIL MIX:
Cement=285kg/m^3
fly ash =122kg/m^3
water=149kg
coarse aggregate=1189/m^3
fine aggregate =728 kg /m^3
chemical admixture=7.6kg/m^3
water cement ratio=0.366
trail mix ratio:285:728:1189=1:2.55:
4.17(C:FA:CA)
*This trail mix ratio should match the workability durability ,minimum strength of M35 grade concrete
*If it does not stisfy the above criteria two or more trails for increase of 10%should be done.