Project on Concrete Mix Design for various grades of Concrete
Mix design for M35 grade concrete:
Aim : Mix design for M35 grade concrete with fly ash.
Procedure:
1.Grade designation:M35
2.Type of cement:OPC 43 grade
3.Replacement material for cement:fly ash
4.Nominal size of aggregate:20mm
5.Minimum cement content:320 kg/m^3(as per IS 456-2000,Table 5)
6.Maximum w/c ratio will be 0.45
7.Exposure condition:severe
8.Workability of concrete:100mm slump value pumping concrete
9.Method of placing:pumping concrete
10.Degree of supervision:Good
11.Type of aggregate:Crushed angular aggregate
12.Maximum cement content:450 kg/m^3
13.Type of chemical admixture:superplasticizer
Test data for materials:
1.Cement used:OPC 43 Grade
2.Specific gravity of cement:3.15
3.Fly ash:Confirming to IS 3812
4.Specifc gravity of fly ash:2.2
5.Admixture:Superplasticizer confirming to IS 9103
6.Specific gravity of aggregate:
Coarse aggregate:2.74
Fine aggregate:2.74
7.Water absorption:
Coarse aggregate:0.5%
Fine aggregate:1%
8.Free surface moisture:
Coarse aggregate:Nil
Fine aggregate:Nil
Determine the target mean strength:
f'ck=fck+1.65S
fck=chareteristic compressive strength
S=Standard deviation
=35+1.65*5=43.25 N/mm^2.
Determination of w/c ratio:
Maximum w/c ratio=0.45 as per IS 456-2000(severe condition)
by trial experiance w/c ratio will be 0.4
0.4<0.45 hence OK.
Water content:
As per table 2 of IS 10262-2009,
For 20mm nominal size aggregate water content will be 186 litres.
For 100mm slump 6% of water content will added,in that case
186+(186*6/100)=197 litres
According to trials,29% of water content will reduced by adding superplasticizer
so, 197-(29/100*197)=139.9=140 litres.
Cement content:
w/c ratio=0.4
cement content=140/0.4=350 kg/m^3
minimum cement content for severe condition is 320 kg/m^3
350 kg/m^3>320 kg/m^3 hence ok.
Addition of fly ash:
10% cementitious material will added.so,
cementitious material=350*1.1=385 kg/m^3
water content is 140 litres
so w/c ratio;
140/385=0.36
Fly ash at 30% of total cementitious material content:
385-30%=115 kg/m^3
cement (OPC):385-115=270 kg/m^3
fly ash:115 kg/m^3
Proportion of volume of coarse aggregate and fine aggregate:
Volume of coarse aggregate of 20mm and fine aggregate(zone1) for w/c ratio will be 0.6(as per IS 10262-2009,table 3)
In this case the w/c ratio=0.4
Therefore,the volume of coarse aggregate needs to be increased to decrease the fine aggregate content.
As the w/c ratio is lowered by 0.1,the proportion of volume of coarse aggregate is increased by 0.2( at the rate of +/- 0.01 for every +/- 0.05 change in water- cement ratio)
Hence the corrected w/c ratio for coarse aggregate ratio=0.64
(if the coarse aggregate is not in angular type the volume of coarse aggregate will increased accordingly,as per trial experiance)
For pumping concrete, these are reduced by 10 %
Volume of coarse aggregate =0.64*0.9 = 0.576
Volume of fine aggregate =1-0.576 =0.424
Mix calculation:
Mix calculation per unit volume of concrete:
a. Volume of concrete = 1 m^3
b. Volume of cement = (Mass of cement / Specific gravity of cement ) *1/1000
=(270/3.15)*1/1000=0.086 m^3
c. Volume of flyash = (Mass of flyash / Specific gravity of flyash )*1/1000
=(115/2.2)*1/1000=0.052 m^3
d. Volume of water = ( Mass of water / Specific gravity of water)*1/1000
= (140/1)*1/1000=0.140 m^3
e. Volume of chemical admixture = ( Mass of admixture / specific gravity of admixture)*1/1000
=(7.6/1.14)*1/1000=0.006 m^3
f. Volume of aggregate ( Fine and coarse) = a- (b+c+d+e)
=1-(0.086+0.052+0.140+0.006)
=0.716 m^3
g. Mass of coarse aggregate = f* Volume of coarse aggregate * Specific gravity of coarse aggregate*1000
=0.716*0.576*2.74*1000=1130 kg/m^3
h. Mass of fine aggregate = f* Volume of fine aggregate* Specific gravity of fine aggregate*1000
=0.716*0.424*2.74*1000=831 kg/m^3
Mix proportion:
Cement=270 kg/m^3
Fly ash=115 kg/m^3
Water=140 kg/m^3
Coarse aggregate=1130 kg/m^3
Fine aggregate=831 kg/m^3
Chemical admixture=7 kg/m^3
w/c ratio=0.36
Mix ratio=1:2.15:2.94
Result:
For obtain the required slump on trial, the water content and dosage of chemical admixture shall be adjusted and mix proportion shall be reworked for actual water content for durability requirements.2 or more trials have variation of 10% in w/c ration in clause 10(step 10) shall be carried out and a graph between three water -cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for feild trials .However durability shall be met.
The mix design for M35 grade of concrete with flyash= 1: 2.15:2.94
Mix design for M50 grade concrete
Aim:Mix design for M50 grade concrete
Procedure:
1.Grade designation:M50
2.Type of cement:OPC 43 grade
3.Nominal size of aggregate:20mm
4.Minimum cement content:320 kg/m^3(as per IS 456-2000,Table 5)
5.Maximum w/c ratio will be 0.45
6.Exposure condition:severe
7.Workability of concrete:100mm slump value pumping concrete
8.Method of placing:pumping concrete
9.Degree of supervision:Good
10.Type of aggregate:Crushed angular aggregate
11.Maximum cement content:450 kg/m^3
12.Type of chemical admixture:superplasticizer.
Test data for materials:
a. Cement used : OPC 43 grade confirming to IS 8112
b. Specific gravity of cement : 3.15
c. Chemical admixture : Superplaticizer conforming to IS 9103
d. Specific gravity:
Coarse aggregate : 2.74
Fine aggregate : 2.74
e. Water absorption :
Coarse aggregate : 0.5%
Fine aggregate : 1%
f. Free surface moisture
Coarse aggregate : Nil
Fine aggregate : Nil
Determination of target mean strength:
f'ck=fck+1.65S
fck=chareteristic compressive strength
S=Standard deviation
=50+1.65*5=58.25 N/mm^2.
Determination of w/c ratio:
Maximum w/c ratio=0.45 as per IS 456-2000(severe condition)
by trial experiance w/c ratio will be 0.4
0.4<0.45 hence OK.
Water content:
As per table 2 of IS 10262-2009,
For 20mm nominal size aggregate water content will be 186 litres.
For 100mm slump 6% of water content will added,in that case
186+(186*6/100)=197 litres
According to trials,29% of water content will reduced by adding superplasticizer
so, 197-(29/100*197)=139.9=140 litres.
Cement content:
w/c ratio=0.4
cement content=140/0.4=350 kg/m^3
minimum cement content for severe condition is 320 kg/m^3
350 kg/m^3>320 kg/m^3 hence ok.
Proportion of volume of coarse aggregate and fine aggregate:
Volume of coarse aggregate of 20mm and fine aggregate(zone1) for w/c ratio will be 0.6(as per IS 10262-2009,table 3)
In this case the w/c ratio=0.4
Therefore,the volume of coarse aggregate needs to be increased to decrease the fine aggregate content.
As the w/c ratio is lowered by 0.1,the proportion of volume of coarse aggregate is increased by 0.2( at the rate of +/- 0.01 for every +/- 0.05 change in water- cement ratio)
Hence the corrected w/c ratio for coarse aggregate ratio=0.64
(if the coarse aggregate is not in angular type the volume of coarse aggregate will increased accordingly,as per trial experiance)
For pumping concrete, these are reduced by 10 %
Volume of coarse aggregate =0.64*0.9 = 0.576
Volume of fine aggregate =1-0.576 =0.424
Mix calculation:
Mix calculation per unit volume of concrete:
a. Volume of concrete = 1 m^3
b. Volume of cement = (Mass of cement / Specific gravity of cement ) *1/1000
=(350/3.15)*1/1000=0.111 m^3
c. Volume of water = ( Mass of water / Specific gravity of water)*1/1000
= (140/1)*1/1000=0.140 m^3
d. Volume of chemical admixture = ( Mass of admixture / specific gravity of admixture)*1/1000
=(7.6/1.14)*1/1000=0.006 m^3
e. Volume of aggregate ( Fine and coarse) = a- (b+c+d)
=1-(0.111+0.140+0.006)
=0.743 m^3
f. Mass of coarse aggregate = f* Volume of coarse aggregate * Specific gravity of coarse aggregate*1000
=0.753*0.576*2.74*1000=1173 kg/m^3
g. Mass of fine aggregate = f* Volume of fine aggregate* Specific gravity of fine aggregate*1000
=0.753*0.424*2.74*1000=863 kg/m^3
Mix proportion:
Cement=350 kg/m^3
Water=140 kg/m^3
Coarse aggregate=1173 kg/m^3
Fine aggregate=863 kg/m^3
Chemical admixture=7 kg/m^3
w/c ratio=0.4
Mix ratio:1:2.46:3.35
Result:
For obtain the required slump on trial, the water content and dosage of chemical admixture shall be adjusted and mix proportion shall be reworked for actual water content for durability requirements.2 or more trials have variation of 10% in w/c ration in clause 10(step 10) shall be carried out and a graph between three water -cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for feild trials .However durability shall be met.
Mix design for M50 grade concrete is 1:2.46:3.35.