Project on Concrete Mix Design for various grades of Concrete
QUE )
ANS :-
. Concrete mix design for M35 with fly ash
Data required:
Grade designation: M35 with 10% of flyash
Type of cement: OPC 43 grade conforming to IS 8112
Maximum nominal size of aggregate: 20mm
Exposure type: Very Severe
Minimum cement content: 340 kg/m^3
Workability: 100mm slump
Method of concrete placing: Pumping
Type of aggregate: Crushed angular
Maximum cement content: 450 kg/m^3
Chemical admixture : Super plasticizer
Specific gravity of cement: 3.15
Specific gravity of fly ash: 2.2
Specific gravity of fine aggregate: 2.61
Specific gravity of coarse aggregate: 2.73
Coarse and fine aggregate: Grade 1
Target strength:
f'ck = fck + 1.65s
s = 5 (From table 1 of IS 10262 2009)
f'ck = 35 + (1.65 x 5) = 43.25 N/mm^2
Selection of water cement ratio:
From table 5 IS 456:2000, For severe exposure condition maximum w/c = 0.45
Adopt w/c = 0.41
Selection of water content:
Maximum water content = 186lit (From Table 2, 10262: 2009)
For 75mm slump, water content = 186 + ((6/100)x186) ≈">≈≈197
Super plasticizer reduces 29% of water content.
Hence new water content = (71/100)x197 = 139.87
Calculating cement content:
Water/cement = 0.41
cementitious content = 139.87/0.41 = 341.14 > 340 kg/m^3
Therefore cementitious content = 341.14 kg/m^3
Here cement is replaced by 20% fly ash, therefore increase the total cementitious content by 10%
Cementitious content = 1.10x341.14 = 375.25 kg/m^3
New water cement ratio = 139.87/375.25 = 0.37
20% fly ash of cementitious content = 75.05 kg/m^3
Cement = 375.25 - 75.05 = 300.2 kg/m^3
2% of super plasticizer of cementitious content = (2/100)x375.25 = 7.505 kg/m^3
Proportioning of volume of coarse and fine aggregate:
From table 3 IS 10262:2009, for 0.5 w/c, volume of coarse aggregate = 0.6
As per A7 IS 10262:2009, for w/c = 0.37 the volume of coarse aggregate = 0.626
Since the concrete is pumpable, volume of coarse aggregate is reduced by 10%
Volume of coarse aggregate = 0.626x0.9=0.56
Volume of fine aggregate = 1-0.56 = 0.44
Mix calculations:
a. Volume of concrete = 1m^3
b. Volume of cement = (Mass of cement/specific gravity of cement)x(1/1000)
= (300.2/3.15)x(1/1000) = 0.095 m^3
c. Volume of fly ash = (Mass of flyash/specific gravity of flyash)x(1/1000)
= (75.05/2.2)x(1/1000) = 0.034 m^3
d. Volume of water = (Mass of water/specific gravity of water)x(1/1000)
= (139.87/1)x(1/1000) = 0.139 m^3
e. Super plasticizer is upto 2% of mass of total cementitious content
= (7.505/1.15)x(1/1000) = 0.006 m^3
f. Volume of aggregate = a - (b+c+d+e) = 1- (0.095+0.034+0.139+0.006) = 0.726 m^3
g. Mass of coarse aggregate = f x volume of coarse aggregate x specific gravity of coarse aggregate
= 0.726x0.56x2.73x1000 = 1110 kg
h. Mass of fine aggregate = f x volume of fine aggregate x specific gravity of fine aggregate
= 0.726 x 0.44 x 2.61
= 834 kg
Mix Proportioning:
Cement = 300.2 kg/m^3
Flyash = 75.05 kg/m^3
Fine aggregate = 834 kg/m^3
Coarse aggregate = 1110 kg/m^3
W/C = 0.37
Admixture = 7.505 kg/m^3
2. Concrete mix design for M50 without fly ash
Data required:
Grade designation: M50
Type of cement: OPC 43 grade conforming to IS 8112
Maximum nominal size of aggregate: 20mm
Exposure type: Extreme (reinforced)
Minimum cement content: 360 kg/m^3
Workability: 100mm slump
Method of concrete placing: Pumping
Type of aggregate: Crushed angular
Maximum cement content: 450 kg/m^3
Chemical admixture : Super plasticizer
Specific gravity of cement: 3.15
Specific gravity of fine aggregate: 2.61
Specific gravity of coarse aggregate: 2.73
Coarse and fine aggregate: Grade 1
Target strength:
f'ck = fck + 1.65s
s = 5 (From table 1 of IS 10262 2009)
f'ck = 50 + (1.65 x 5) = 58.25 N/mm^2
Selection of water cement ratio:
From table 5 IS 456:2000, For severe exposure condition maximum w/c = 0.40
Adopt w/c = 0.33
Selection of water content:
Maximum water content = 186lit (From Table 2, 10262: 2009)
For 100mm slump, water content = 186 + ((6/100)x186) ≈">≈≈197
Super plasticizer reduces 29% of water content.
Hence new water content = (71/100)x197 = 139.87
Calculating cement content:
Water/cement = 0.33
cementitious content = 139.87/0.33 = 424 > 360 kg/m^3
Therefore cementitious content = 424 kg/m^3
2.5% of super plasticizer of cementitious content = (2.5/100)x424 = 10.6 kg/m^3
Proportioning of volume of coarse and fine aggregate:
From table 3 IS 10262:2009, for 0.5 w/c, volume of coarse aggregate = 0.6
As per A7 IS 10262:2009, for w/c = 0.33 the volume of coarse aggregate = 0.636
Since the concrete is pumpable reduce the volume of coarse aggregate by 10%
Volume of coarse aggregate = 0.636x.91 = 0.578
Volume of fine aggregate = 1-0.578 = 0.421
Mix calculations:
a. Volume of concrete = 1m^3
b. Volume of cement = (Mass of cement/specific gravity of cement)x(1/1000)
= (424/3.15)x(1/1000) = 0.134 m^3
c. Volume of water = (Mass of water/specific gravity of water)x(1/1000)
= (139.87/1)x(1/1000) = 0.139 m^3
d. Super plasticizer is upto 2% of mass of total cementitious content
= (10.6/1.15)x(1/1000) = 0.0092 m^3
e. Volume of aggregate = a - (b+c+d+) = 1- (0.134+0.139+0.0092) = 0.717 m^3
f. Mass of coarse aggregate = f x volume of coarse aggregate x specific gravity of coarse aggregate
= 0.717x0.578x2.73x1000 = 1131 kg
g. Mass of fine aggregate = f x volume of fine aggregate x specific gravity of fine aggregate
= 0.717 x 0.421 x 2.61x1000
= 787 kg
Mix Proportioning:
Cement = 424 kg/m^3
Fine aggregate = 787 kg/m^3
Coarse aggregate = 11131 kg/m^3
W/C = 0.33
Admixture = 10.6 kg/m^3