Project on Concrete Mix Design for various grades of Concrete
1. The concrete mis design for M35 grade concrete with fly ash?
Ans: Step to be followed:
1. Traget mean strength
F'CK = FCK+1.65S
F'CK = Target average compressive strength at 28 days
FCK = Charachterstic compressive strength at 28 days
S = Standard deviation
2. Cement content :
cement content = water content / water - cement ratio
3. Volume calculation:
a) Volume of concrete
b) Volume of cement = [Mass of cement] / [Specific Gravity of Cement] x 1/1000
c) Volume of water = [Mass of water] / [Specific Gravity of water] x 1/1000
d) Volume of chemical admixture = [Mass of admixture] / [Specific Gravity of admixture] x 1/1000
e) Volume of all in aggregate =[a-(b+c+d)]
f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
For concrete mix design :
Grade of concrete : M35
Type of cement : OPC 43
Type of mineral admixture : Fly ash conforming to IS 3812
Max nominal size aggregate : 20MM
Minimum cement content : 320kg/m3 Table no: 5 IS 2000
Maximum water-cement ratio : 0.45 Table no: 5 IS 2000
Workability : 100mm (slump value for pumpable concrete)
Exposure condition : severe
Method of concrete placing : Pumping
Degree of supervision : Good
Type of aggregate : Crushed angular aggregate
Maximum cement content : 450kg/m^3
Chemical admixture type : super plasticizer
Specific gravity of water : 1
Specific gravity of cement : 3.15
Specific gravity of coarse aggregate : 2.74
Specific gravity of fine aggregate : 2.74
Specific gravity of fly ash : 2.2
water absorbation of coarse aggregate : 0.5%
water absorbation of fine aggregate : 1%
Sieve analysis: coarse aggregate : Conforming to table 2 IS 383
Sieve analysis: Fine aggregate : Conforming to grading zone II table 4
Free surface moisture:
Coarse aggregate : Nil
Fine aggregate : Nil
Target strength for mix proportion :
F'CK = FCK + 1.65 X S
= 35 + 1.65 X 5
= 43.25 N/MM2.
Selection of water-cement ratio :
From table 5 of IS 456: 2000 for severe expouser, maximum water-cement ratio = 0.45
Based on experience, adopt water cement ratio as 0.40
0.40<0.45 OK
Selection of water content :
The slump value is 100m
water content = 186 + (6/100)186
= 186 + 0.06x186
= 197 liter
Based on trials with superplasticizer water content reduction of 30 percent has been achieved. Hence, the arrived water content =197 x 0.7 =137 litre
Cement content :
W/C = 137/0.4
= 342 kg/m3
From table 5 of IS 456 minimum cement content for severe exposure condition = 320 kg/m^3
342 kg/m3 > 320 kg/m3, hence ok
Now, to proportion a mix containing fly ash the following steps are suggested:
a) The percentage of fly ash needs to be decided based on project requirement and quality of materials
b) In some cases increase in cementitious material can be warranted. Increase in cementitious material
content and its percentage may be based on experience and trail
(this example is with increase of 10% cementitious material content)
Cementitious material content = 342 x 1.10 = 376kg/m^3
water content = 137kg/m^3
So, water-cement ratio = 137/376 = 0.364
Fly ash @ 30% total cementious material content = 376 x 30/100 = 112.8kg/m^3
Cement OPC = 376-112 = 264kg/m^3
saving of cement while using fly ash = 342-264 = 78 kg/m^3
Fly ash being utilized = 112 kg/m^3
Volume of coarse aggregate and fine aggregate :
For Nominal size of aggregate = 20mm
By using table no:5 10262 - 2019
= 0.5-w/c x 0.01 + 0.62
0.05
= 0.1x0.01 + 0.62
0.05
= 0.001 +0.62
0.05
= 0.02+0.62
= 0.64 x 0.9
coarse aggregate = 0.576
Fine aggregate = 1-0.576
= 0.424
Mix calculation:
Volume of concrete = 1m3
Mass of cement
The volume of cement: _______________________________* 1/1000
Specific gravity of cemnt
= 264 x 1/1000
3.15
= 0.083m3
volume of water:
Mass of water
The volume of water: _______________________________* 1/1000
Specific gravity of water
= 137 x 1/1000
1
= 0.137
Volume of flyash:
Mass of fly ash
The volume of fly ash: _______________________________* 1/1000
Specific gravity of fly ash
= 112 x 1/1000
2.2
= 0.050
volume of chemical admixture:
Mass of chemical admixture
The volume of chemical admixture: _______________________________* 1/1000
Specific gravity of chemical admixtre
= 7.6/1.145 x 1/1000
= 0.006m3
Volume of aggregate ( CA & FA ):
= (a-(b+c+d+e)
= (1-(0.083+0.137+0.050+0.006))
= 1-0.276
= 0.724m3
Mass of coarse aggregate: e x volume of CA x specific gravity of coarse aggregate x 1000
= 0.724 x 0.576 x 2.74 x 1000
= 1142.645 kg/m3
Mass of fine aggregate: e x volume of fin aggregate x specific gravity of fine aggregate x 1000
= 0.724 x 0.424 x 2.74 x 1000
= 841.114 kg/m3
Mix Proportion :
Cement : 264 kg/m^3
Fly ash : 112 kg/m^3
Water : 197 l/m^3
volume Fine aggregate : 0.576
volume Coarse aggregate : 0.424
Volume of aggregate ( CA & FA ) : 0.724m3
Chemical admixture : 0.006m3
Mass of coarse aggregate : 1142.645 kg/m3
Mass of fine aggregate : 841.114 kg/m3
2. The concrete mis design for M50 grade concrete without fly ash?
Ans:
Step to be followed:
1. Traget mean strength
F'CK = FCK+1.65S
F'CK = Target average compressive strength at 28 days
FCK = Charachterstic compressive strength at 28 days
S = Standard deviation
2. Cement content :
cement content = water content / water - cement ratio
3. Volume calculation:
a) Volume of concrete
b) Volume of cement = [Mass of cement] / [Specific Gravity of Cement] x 1/1000
c) Volume of water = [Mass of water] / [Specific Gravity of water] x 1/1000
d) Volume of chemical admixture = [Mass of admixture] / [Specific Gravity of admixture] x 1/1000
e) Volume of all in aggregate =[a-(b+c+d)]
f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
For concrete mix design :
Grade of concrete : M50
Type of cement : OPC 53
Max nominal size aggregate : 20MM
Minimum cement content : 320kg/m3 Table no: 5 IS 2000
Maximum water-cement ratio : 0.40 Table no: 5 IS 2000
Workability : 100mm (slump value for pumpable concrete)
Exposure condition : Extreme
Method of concrete placing : Pumping
Degree of supervision : Good
Type of aggregate : Crushed angular aggregate
Maximum cement content : 450kg/m^3
Chemical admixture type : super plasticizer
Specific gravity of water : 1
Specific gravity of cement : 3.15
Specific gravity of coarse aggregate : 2.74
Specific gravity of fine aggregate : 2.74
water absorbation of coarse aggregate : 0.5%
water absorbation of fine aggregate : 1%
Sieve analysis: coarse aggregate : Conforming to table 2 IS 383
Sieve analysis: Fine aggregate : Conforming to grading zone III table 4
Free surface moisture:
Coarse aggregate : Nil
Fine aggregate : Nil
Target strength for mix proportion :
F'CK = FCK + 1.65 X S
= 50 + 1.65 X 5
= 58.25 N/MM2.
Selection of water-cement ratio :
From table 5 of IS 456: 2000 for extreme expouser, maximum water-cement ratio = 0.40
Based on experience, adopt water cement ratio as 0.35
0.35<0.40 OK
Selection of water content :
The slump value is 100m
water content = 186 + (6/100)186
= 186 + 0.06x186
= 197 liter
Based on trials with superplasticizer water content reduction of 30 percent has been achieved. Hence, the arrived water content =197 x 0.7 =137 litre
Cement content :
W/C = 137/0.35
= 391.42 kg/m3
Volume of coarse aggregate and fine aggregate :
For Nominal size of aggregate = 20mm
By using table no:5 10262 - 2019
= 0.5-w/c x 0.01 + 0.64
0.05
= 0.15x0.01 + 0.64
0.05
= 0.0015 +0.64
0.05
= 0.03+0.64
= 0.67 x 0.9
coarse aggregate = 0.603
Fine aggregate = 1-0.603
= 0.397
Mix calculation:
Volume of concrete = 1m3
Mass of cement
The volume of cement: _______________________________* 1/1000
Specific gravity of cemnt
= 391 x 1/1000
3.15
= 0.124m3
volume of water:
Mass of water
The volume of water: _______________________________* 1/1000
Specific gravity of water
= 197 x 1/1000
1
= 0.197
volume of chemical admixture:
Mass of chemical admixture
The volume of chemical admixture: _______________________________* 1/1000
Specific gravity of chemical admixtre
= 7.6/1.145 x 1/1000
= 0.006m3
Volume of aggregate ( CA & FA ):
= (a-(b+c+d)
= (1-(0.124+0.197+0.006))
= 1-0.327
= 0.673m^3
Mass of coarse aggregate: e x volume of CA x specific gravity of coarse aggregate x 1000
= 0.673 x 0.603 x 2.74 x 1000
= 1111.944 kg/m3
Mass of fine aggregate: e x volume of fin aggregate x specific gravity of fine aggregate x 1000
= 0.673 x 0.397 x 2.74 x 1000
= 732.075kg/m3
Mix Proportion :
Cement : 391 kg/m^3
Water : 197 l/m^3
volume Fine aggregate : 0.397
volume Coarse aggregate : 0.603
Volume of aggregate ( CA & FA ) : 0.673 m^3
Chemical admixture : 0.006 m^3
Mass of coarse aggregate : 111.944 kg/m3
Mass of fine aggregate : 732.075 kg/m3