Project on Concrete Mix Design for various grades of Concrete
Mix design for M35 grade concrete with fly ash
- grade designation M35
- type of cement OPC43 grade conforming IS 8112
- type of mineral admixture: fly ash conforming Is3812
- maximum nominal size of aggregate 20mm
- minimum cement content 320kg/m^3(from table 5 IS 456:2000)
- maximum water-cement ratio 0.45
- workability: 100mm
- method of concrete placing: pumping
- type of aggregate crushed angular
- exposure condition: severe
- specific gravity of cement: 3.15
- specific gravity of fly ash: 2.2
- specific gravity of fine aggregate: 2.74
- specific gravity of coarse aggregate: 2.74
Target means strength:
f'ck= 35+1.65x5=43.25N/mm^2 (from IS 10262:2009)
selection of water cement ratio:
max w/c ratio = 0.45
but experience we consider = 0.40
selection of water content:
from table-2 IS 10262:2009
20mm size aggregate slump value 25-50 mm range =186 kg
so, calculating the slump value of 100mm = 186+6%x186 = 197kg or liters
The superplasticizer is used to reduce the water content by up to 29%
hence the arrived water content = 197x0.71 = 140 liters
calculation of cement content:
cement content = 140/0.4
cement + fly ash content = 350 kg/m^3
350>320 kg/m^3
hence ok
cementitious material content = 350x1.10 =385k/m^3
water content= 140 kg
so, w/c ratio = 140/385 = 0.364
fly ash @ 30% total cementitious material content = 385x30% =115 kg
cement OPC = 385-115 = 270kg/m^3
proportion of volume of coarse aggregate and fine aggregate content:
from table -3 volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate zone-1 for water-cement ratio 0.50=0.60
for pumpable concrete these values should be reduced by 10%
therefore, volume of coarse aggregate = 0.62x0.9=0.56
the volume of fine aggregate content = 1-0.56=0.44
Mix calculations:
- volume of concrete =1m^3
- volume of cement = 270/3.15 x1/100=0.865 M^3
- volume of fly ash = 115/1 x 1/ 1000= 0.052 m^3
- volume of water =140/1 x 1/1000 = 0.140m^3
- volume of chemical admixture = 7/1.14 x 1/1000 =0.007m^3
- volume of all ingredients = 1-(0.0865+0.052+0.140-0.007) = 0.715 m^3
- mass of coarse aggregate = 0.715x0.56x2.74x1000= 1097 kg
- mass of fine aggregate = 0.715x0.44x2.74x1000= 862 kg
mix proportion
cement :270kg
fly ash: 115kg
coarse aggregate: 1097 kg
fine aggregate: 862kg
water:140
chemical admixture:7 kg
water cement ratio:0.364
proportion=1:3:4
THE MIXED DESIGN OF CONCRETE IS M50
Data required:
Grade designation: M50
Type of cement: OPC 43 grade conforming to IS 8112
Maximum nominal size of aggregate: 20mm
Exposure type: Severe
Minimum cement content: 320 kg/m^3
Workability: 75mm 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 = 0.45
From IS 10262 2019, w/c for target strength 58.25 N/mm^2 = 0.35
Selection of water content:
Maximum water content = 186lit
For 75mm slump, water content = 186 + ((3/100) x186) = 191
Super plasticizer reduces 29% of water content.
Hence new water content = (71/100) x191 = 135.61
Calculating cement content:
Water/cement = 0.4
cement = 135.61/0.4 = 339.025 > 320 kg/m^3
Therefore, cement content = 339 kg/m^3
Proportioning of volume of coarse and fine aggregate:
volume of coarse aggregate for w/c 0.35= 0.624
Since the concrete is pumpable the volume of coarse aggregate is reduced by 10% = 0.624 x 0.9 = 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) x (1/1000)
(339/3.15) x (1/1000) = 0.107 m^3
c. Volume of water = (Mass of water/specific gravity) x (1/1000)
= (135.61/1) x (1/1000) = 0.135 m^3
d. Super plasticizer is upto 2% of mass of total cementitious content
= (6.78/1.15) x (1/1000) = 0.006 m^3
e. Volume of aggregate = a - (b+c+d) = 1- (0.107+0.135+0.006) = 0.752 m^3
f. Mass of coarse aggregate = e x volume of coarse aggregate x specific gravity of coarse aggregate
= 0.752x0.56x2.73x1000 = 1150 kg
g. Mass of fine aggregate = 0.752 x 0.44 x 2.61
= 863 kg
Mix Proportioning:
Cement = 339 kg/m^3
Fine aggregate = 863 kg/m^3
Coarse aggregate = 1150 kg/m^3
W/C = 0.4
Admixture = 7 kg/m^3