Project on Concrete Mix Design for various grades of Concrete
Calculation for M35 concrete with fly ash
1. Stipulations for proportioning
- Grade designation : M35
- Cement used : OPC 53 grade conforming to IS 8112
- Type fo mineral admixture : Fly ash
- Type Maximum nominal size of aggregate : 20mm
- Method of concrete placing : Pumping
- Degree of supervision : Good
- Type of aggregate : Crushed angular aggregate
- Exposure condition : Very severe (for rainforced concrete)
- Workability : 100 mm (slump value for pumpable concrete)
- Minimum cement content : 340 kg/m^3 (from Table 5 of IS 456:2000 - Exposure condition)
- Maximum water cement ratio : 0.45 (From Table 5 of IS 456:2000 - Exposure condition)
- Maximum cement content : 450 kg/m^3
- Chemical admixture type : Superplasticizer conforming to IS 9103
- Specific gravity of chemical admixtue : 1.145
- Specific gravity of cement : 3.15
- Specific gravity of fly ash : 2.2
- Specific gravity of :
- Coarse aggregate : 2.74
- Fine aggregate : 2.74
- Water absorption :
- Coarse aggregate : 0.5%
- Fine aggregate : 1.0%
- Free surface moistue :
- Coarse aggregate : Nil
- Fine aggregate : Nil
Because aggregate should be in dry condition should not be used in wet condition.
A) Data collection :
Grade of concrete : M35
Exposure condition : Very severe
Grade of cement : M53 (OPC)
fck = 35 N/mm^2
Standard Deviation for M35 : 5 N/mm^2 (As per Table 8)
Target mean strength of concrete,
f'ck = fck + 1.65 S
= 35 + (1.65 * 5)
= 43.25 N/mm^2
Target mean strength of concrete = 43.25 N/mm^2
B) Selection of Water cement ratio :
Step 1- As per the Graph -2
Target mean strength of concrete = 43.25 N/mm^2
Hence, we used curce line E.
We assume w/c ratio : 0.41
Step 2- As per the Table-5 of IS 456:2000 (Very severe exposure condition)
Here, the value of w/c ratio is 0.45 for very severe environmental exposure
Hence, we take w/c ratio = 0.45
Now compare all above the two value,
0.41 and 0.45
The lower value of the above two values is adopted as w/c ratio for mix design.
Hence our w/c ratio is : 0.41
C) Selection of Water Content :
From Table 2 of Is 10262:2009, maximum water content for 20mm aggregate : 186 litre (for 25m to 50mm slump range)
Estimated water content for 100mm slump : 186 + 6/100 *186 = 197 litre
As superplasticizer is used, the water content can be reduced up to 30%
Based on trials water content reduction of 27% is achieved with plasticizer.
Hence the arrived water content : 197*0.73 = 144 litre
D) Calculation of Cement Content :
Water cement ratio = 0.41
Cementitious material (Cement+Fly ash) content = 144 / 0.41 = 351 kg/m^3
From Table 5 of IS 456:2000 minimum cement content for 'very severe' exposure condition = 340kg/m^3
351 kg/m^3 > 340 kg/m^3, Hence OK
Now, to proportion a mix containing fly ash the following steps are suggested:
Increase in cementitions materials content and its percentage may be based on experience and trial
increase of 10% cementitious material content.
Cementitious material content = 351 x 1.10 = 386kg/m3
Water content = 144 kg/m^3
So, Water Cement Ratio = 144/386 = 0.373
Fly ash @ 30% total cementitious materrial content = 386 x 30% = 116 kg/m^3
Cement = 386 - 116 = 270 kg/m^3
Saving of cement wihil using fly ash = 351 - 270 = 81 kg/m^3
Fly ash being utilized = 116 kg/m^3
E) Proportion of volume of coarse and fine aggregate content :
From Table 3 of IS 10262:2009, Volume of coarse aggregate corresponding to 20 mm size of aggregate and
fine aggregate (Zone 2) for w/c ratio = 0.62
In the present case the water cement ratio is 0.41
Threrfore, the voulume of coarse aggregate needs to be increased to decrease the fine aggregate content.
As w/c ratio is lower by 0.10, the proportion of volume of coarse aggregate is increased by 0.02.
(At the rate of +/- 0.01 for every +/- 0.05 change in w/c ratio)
Therefore, corrected volume of coarse aggregate for wa/c ratio of 0.41 = 0.64
(Note: If coarse aggregate is not of angular type, than also the volume of coarse aggregate may be
required to be increased suitably, based on experience)
For pumpable concrete these values are reduced by 10%
Therefore, volume of coarse aggregate = 0.64*.09 = 0.58
Volume of fine aggregate content = 1 - 0.58 = 0.42
F) Mix calculations :
a. Volume of concrete = 1 m^3
b. Volume of cement = 270 / 3.15 x 1/1000 = 0.085 m^3
c. Volume of Fly ash = 116 / 2.2 x 1/1000 = 0.053 m^3
d. Volume of Water = 144 / 1 x 1/1000 = 0.144 m^3
e. Volume of chemical admixture = 7.0 / 1.145 x 1/1000 = 0.006 m^3
f. Volume of aggregate (CA & FA) = (a-(b+c+d+e))
= (1-(0.085+0.053+0.144+0.006))
= (1-0.288) = 0.712 m^3
g. Mass of coarse aggregate = f x volume of coarse aggregate x specific gravity of coarse aggregate x 1000
= 0.712 x 0.58 x 2.74 x 1000
= 1132 kg/m^3
h. Mass of fine aggregate = f x volume of fine aggregate x specific gravity of fine aggregate x 1000
= 0.712 x 0.42 x 2.74 x 1000
= 819 kg/m^3
G) Mix proportions for trial:
Cement = 270 kg/m^3
Fly ash = 116 kg/m^3
Water = 144 kg/m^3
Coarse aggregate = 1132 kg/m^3
Fine aggregate = 819 kg/m^3
Chemical admixture = 7 kg/m^3
W/C ratio = 0.373
Trial Mix Ratio = 1 : 2.12 : 2.93
&
Calculation for M50 grade concrete without fly ash
1. Stipulations for proportioning
- Grade designation : M50
- Cement used : OPC 43 grade conforming to IS 8112
- Type Maximum nominal size of aggregate : 20mm
- Method of concrete placing : Pumping
- Degree of supervision : Good
- Type of aggregate : Crushed angular aggregate
- Exposure condition : Severe (for rainforced concrete)
- Workability : 75 mm (slump value for pumpable concrete)
- Minimum cement content : 320 kg/m^3 (from Table 5 of IS 456:2000 - Exposure condition)
- Maximum water cement ratio : 0.45 (From Table 5 of IS 456:2000 - Exposure condition)
- Maximum cement content : 450 kg/m^3
- Chemical admixture type : Superplasticizer conforming to IS 9103
- Specific gravity of chemical admixtue : 1.145
- Specific gravity of cement : 3.15
- Specific gravity of :
- Coarse aggregate : 2.74
- Fine aggregate : 2.74
- Water absorption :
- Coarse aggregate : 0.5%
- Fine aggregate : 1.0%
- Free surface moistue :
- Coarse aggregate : Nil
- Fine aggregate : Nil
Because aggregate should be in dry condition should not be used in wet condition.
A) Data collection :
Grade of concrete : M50
Exposure condition : Severe
Grade of cement : M43 (OPC)
fck = 50 N/mm^2
Standard Deviation for M50 : 5 N/mm^2 (As per Table 8)
Target mean strength of concrete,
f'ck = fck + 1.65 S
= 50 + (1.65 * 5)
= 58.25 N/mm^2
Target mean strength of concrete = 58.25 N/mm^2
B) Selection of Water cement ratio :
Step 1- As per the Graph -2
Target mean strength of concrete = 58.25 N/mm^2
Hence, we used curce line F.
We assume w/c ratio : 0.35
Step 2- As per the Table-5 of IS 456:2000 (Very severe exposure condition)
Here, the value of w/c ratio is 0.45 for severe environmental exposure
Hence, we take w/c ratio = 0.45
Now compare all above the two value,
0.35 and 0.45
The lower value of the above two values is adopted as w/c ratio for mix design.
Hence our w/c ratio is : 0.35
C) Selection of Water Content :
From Table 2 of Is 10262:2009, maximum water content for 20mm aggregate : 186 litre (for 25m to 50mm slump range)
Estimated water content for 75mm slump : 186 + 3/100 *186 = 192 litre
As superplasticizer is used, the water content can be reduced up to 30%
Based on trials water content reduction of 27% is achieved with plasticizer.
Hence the arrived water content : 192*0.73 = 140 litre
D) Calculation of Cement Content :
Water cement ratio = 0.35
Cement content = 140 / 0.35 = 400 kg/m^3
From Table 5 of IS 456:2000 minimum cement content for 'severe' exposure condition = 320kg/m^3
400 kg/m^3 > 320 kg/m^3, Hence OK
E) Proportion of volume of coarse and fine aggregate content :
From Table 3 of IS 10262:2009, Volume of coarse aggregate corresponding to 20 mm size of aggregate and
fine aggregate (Zone 1) for w/c ratio = 0.60
In the present case the water cement ratio is 0.35
Threrfore, the voulume of coarse aggregate needs to be increased to decrease the fine aggregate content.
As w/c ratio is lower by 0.10, the proportion of volume of coarse aggregate is increased by 0.02.
(At the rate of +/- 0.01 for every +/- 0.05 change in w/c ratio)
Therefore, corrected volume of coarse aggregate for wa/c ratio of 0.35 = 0.62
(Note: If coarse aggregate is not of angular type, than also the volume of coarse aggregate may be
required to be increased suitably, based on experience)
For pumpable concrete these values are reduced by 10%
Therefore, volume of coarse aggregate = 0.62*.09 = 0.56
Volume of fine aggregate content = 1 - 0.56 = 0.44
F) Mix calculations :
a. Volume of concrete = 1 m^3
b. Volume of cement = 400 / 3.15 x 1/1000 = 0.127 m^3
c. Volume of Water = 140 / 1 x 1/1000 = 0.140 m^3
d. Volume of chemical admixture = 8 / 1.145 x 1/1000 = 0.007 m^3
e. Volume of aggregate (CA & FA) = (a-(b+c+d))
= (1-(0.127+0.140+0.007))
= (1-0.274) = 0.726 m^3
f. Mass of coarse aggregate = f x volume of coarse aggregate x specific gravity of coarse aggregate x 1000
= 0.726 x 0.56 x 2.74 x 1000
= 1114 kg/m^3
g. Mass of fine aggregate = f x volume of fine aggregate x specific gravity of fine aggregate x 1000
= 0.726 x 0.44 x 2.74 x 1000
= 875 kg/m^3
G) Mix proportions for trial:
Cement = 400 kg/m^3
Water = 140 kg/m^3
Coarse aggregate = 1114 kg/m^3
Fine aggregate = 875 kg/m^3
Chemical admixture = 8 kg/m^3
W/C ratio = 0.35
Trial Mix Ratio = 1 : 2.19 : 2:79