Project on Concrete Mix Design for various grades of Concrete
1. Mix Design for M35 grade concrete with fly ash.
Aim: To Calculate the Mix Design for M35 grade concrete with fly ash.
1. Given and Assumed Data:
- Grade Designation: M35
- Type of cement: OPC 43 grade conforming to IS 8112
- Type of mineral admixture: Fly ash conforming to IS 3812 (Part-1)
- Maximum Nominal Size of aggregate: 20 mm
- Exposure condition: Moderate ( for reinforced concrete )
- Minimum Cement content: 300 kg/m^3 ( IS 456:2000 Table-5, Exposure condition )
- Maximum Water-cement ratio: 0.50 ( IS 456:2000 Table-5, Exposure condition )
- Workability: 100 mm ( Slump value for pumpable concrete )
- Method of Concrete Placing: Pumping
- Degree of Supervision: Good
- Type of Aggregate: Crushed angular aggregate
- Maximum cement content: 450 kg/m^3
- Chemical admixture type: Superplasticizer conforming to IS 9103
2. Test Data for materials:
- Specific Gravity of cement: 3.15
- Specific Gravity of flyash: 2.2
- Specific Gravity of Coarse and Fine aggregate: 2.74
- Water absorption of Coarse aggregate: 0.5%
- Water absorption of Fine aggregate: 1%
- Free Surface Moisture of Coarse and Fine aggregate: Nil
- Sieve Analysis:
- Coarse aggregate: Conforming to Table-2 of IS 383
- Fine aggregate: Conforming to grading Zone-1 of Table-4 of IS 383
3. Target Strength for Mix Proportioning:
Formulae: f'ck= fck+1.65s
f'ck= Target mean strength
fck= compressive strength of given concrete grade.
s= Standard Deviation
In this case,
s= 5 N/mm^2 ( IS 10262:2009 Table-1 )
Therefore, f'ck= 35+1.65X5 = 43.25 N/mm^2
4. Selection of Water-cement ratio:
With reference to Table-5 of IS 456:2000 for Moderate exposure, maximum Water-cement ratio= 0.50
Based on experience, adopt water-cement ratio= 0.35
0.35<0.50, Hence OK
5. Selection of Water content:
With reference to Table-2 of IS 10262:2009, Maximum Water content for 20 mm aggregate= 186 litres ( for 25 mm to 50 mm slump range ).
Estimated water content for 100 mm slump= 186+(6/100)X186 = 197 litres
As super plasticizer is used, the water content can be reduced upto 20% and above.
Based on trials water content reduction of 29% is achieved with plasticizer.
Hence the arrived water content= 197x0.71= 140 litres
6. Calculation of Cement content:
Water-cement ratio= 0.35
Cementious material ( Cement+Flyash ) content = 140/0.35 = 400 kg/m^3
From Table-5 pf IS 456:2000 for Moderate exposure, Minimum Cement Content for moderate exposure condition = 300 kg/m^3
400 kg/m^3>300 kg/m^3, Hence OK
Now, to proportion a mix containing flyash the following steps are suggested:
- The percentage of flyash must be decided based on project requirement and quality of materials.
- In some cases increase in cementitious material can be warranted. Increase in cementitious material content and its percentage may be based on experience and trial ( In this problem is with increase of 10% cementious material content)
Cementitious material content= 400x1.10= 440 kg/m^3
Water content= 140 kg/m^3
So, Water-cement ratio= 140/440= 0.32
Flyash@ 30% of total cementitious material contnet= 440X(30/100)= 132 kg/m^3
Cement (OPC )= 440-132= 308 kg/m^3
Saving of cement while using fly ash= 400-308= 92 kg/m^3
Flyash being utilized= 132 kg/m^3
7. Proportion of Volume of Coarse aggregate and Fine aggregate content:
From Table-3 of IS 10262:2009, Volume of Coarse aggregate corresponding to 20 mm size aggregate and Fine aggregate ( Zone-1 ) for water-cement ratio= 0.6
In the present case, Water-cement ratio is 0.35
- Therefore, the volume of Coarse aggregate needs to be increased to decrease the fine aggregate content.
- As water-cement ratio is lower by 0.15, the proportion of volume of Coarse aggregate is increased by 0.03 ( at the rate of +/-0.01 for every +/-0.05 change in Water-cement ratio ).
Therefore, corrected volume of Coarse aggregate for the Water-cement ratio of 0.35= 0.6+0.03= 0.63
For pumpable concrete these values must be reduced by 10%.
Therefore, volume of Coarse aggregate = 0.63X0.9 = 0.567
Volume of Fine aggregate= 1-0.567 = 0.433
8. Mix Calculations:
The Mix calculations per unit volume shall be as follows:
- Volume of Concrete= 1 m^3
- Volume of Cement= ( Mass of Cement/Specific gravity of cement )X(1/1000)= (308/3.15)X(1/1000)= 0.097 m^3
- Volume of Flyash= ( Mass of Flyah/Specific gravity of flyash )X(1/1000)= (132/2.2)X(1/1000)= 0.06 m^3
- Volume of Water= ( Mass of Water/Specific gravity of water )X(1/1000)= (140/1)X(1/1000)= 0.14 m^3
- Volume of Chemical Admixture= ( Mass of Chemical Admixture/Specific gravity of chemical admixture )X(1/1000)= (7.6/1.145)X(1/1000)= 0.006 m^3
- Volume of aggregate (FA and CA)= (a-(b+c+d+e))= (1-(0.097+0.06+0.14+0.006))= 0.697 m^3
- Mass of Coarse aggregate= f X Volume of coarse aggregate X Specific gravity of Coarse aggregate X 1000= 0.697 X 0.567 X 2.74 X 1000= 1083 kg/m^3
- Mass of Fine aggregate= f X Volume of fine aggregate X Specific gravity of fine aggregate X 1000= 0.697X 0.433 X 2.74 X 1000= 827 kg/m^3
9. Mix proportions for Trial Number-1:
Cement= 308 kg/m^3
Flayash= 132 kg/m^3
Water= 140 kg/m^3
Fine aggregate= 827 kg/m^3
Coarse aggregate= 1083 kg/ m^3
Chhemical admixture= 7 kg /m^3
Water-cement ratio= 0.32
Trial Mix ratio= 1 : 2.68: 3.51
2. Mix Design for M50 grade concrete without fly ash.
Aim: To Calculate the Mix Design for M50 grade concrete without fly ash.
1. Given and Assumed Data:
- Grade Designation: M50
- Type of cement: OPC 53 grade conforming to IS 12269:2013
- Maximum Nominal Size of aggregate: 40 mm
- Exposure condition: Extreme ( for reinforced concrete )
- Minimum Cement content: 360-30= 330 kg/m^3 ( IS 456:2000 Table-5, Exposure condition ) and -30 kg/m^3 ( IS 456:2000 Table-6 )
- Maximum Water-cement ratio: 0.40 ( IS 456:2000 Table-5, Exposure condition )
- Workability: 100 mm ( Slump value for pumpable concrete )
- Method of Concrete Placing: Pumping
- Degree of Supervision: Good
- Type of Aggregate: Crushed angular aggregate
- Maximum cement content: 450 kg/m^3
- Chemical admixture type: Superplasticizer conforming to IS 9103
2. Test Data for materials:
- Specific Gravity of cement: 3.15
- Specific Gravity of Coarse and Fine aggregate: 2.74
- Water absorption of Coarse aggregate: 0.5%
- Water absorption of Fine aggregate: 1%
- Free Surface Moisture of Coarse and Fine aggregate: Nil
- Sieve Analysis:
- Coarse aggregate: Conforming to Table-2 of IS 383
- Fine aggregate: Conforming to grading Zone-1 of Table-4 of IS 383
3. Target Strength for Mix Proportioning:
Formulae: f'ck= fck+1.65s
f'ck= Target mean strength
fck= compressive strength of given concrete grade.
s= Standard Deviation
In this case,
s= 5 N/mm^2 ( IS 10262:2009 Table-1 )
Therefore, f'ck= 50+1.65X5 = 58.25 N/mm^2
4. Selection of Water-cement ratio:
With reference to Table-5 of IS 456:2000 for Extreme exposure, maximum Water-cement ratio= 0.40
Based on experience, adopt water-cement ratio= 0.30
0.30<0.40, Hence OK
5. Selection of Water content:
With reference to Table-2 of IS 10262:2009, Maximum Water content for 40 mm aggregate= 165 litres ( for 25 mm to 50 mm slump range ).
Estimated water content for 100 mm slump= 165+(6/100)X165 = 175 litres
As super plasticizer is used, the water content can be reduced upto 20% and above.
Based on trials water content reduction of 29% is achieved with plasticizer.
Hence the arrived water content= 175x0.71= 125 litres
6. Calculation of Cement content:
Water-cement ratio= 0.30
Cement content = 125/0.30 = 417 kg/m^3
From Table-5 pf IS 456:2000 for Moderate exposure, Minimum Cement Content for extreme exposure condition = 330 kg/m^3
417 kg/m^3>330 kg/m^3, Hence OK
7. Proportion of Volume of Coarse aggregate and Fine aggregate content:
From Table-3 of IS 10262:2009, Volume of Coarse aggregate corresponding to 40 mm size aggregate and Fine aggregate ( Zone-1 ) for water-cement ratio= 0.69
In the present case, Water-cement ratio is 0.30
- Therefore, the volume of Coarse aggregate needs to be increased to decrease the fine aggregate content.
- As water-cement ratio is lower by 0.20, the proportion of volume of Coarse aggregate is increased by 0.04 ( at the rate of +/-0.01 for every +/-0.05 change in Water-cement ratio ).
Therefore, corrected volume of Coarse aggregate for the Water-cement ratio of 0.30 = 0.69+0.04= 0.73
For pumpable concrete these values must be reduced by 10%.
Therefore, volume of Coarse aggregate = 0.73X0.9 = 0.657
Volume of Fine aggregate= 1-0.657 = 0.343
8. Mix Calculations:
The Mix calculations per unit volume shall be as follows:
- Volume of Concrete= 1 m^3
- Volume of Cement= ( Mass of Cement/Specific gravity of cement )X(1/1000)= (417/3.15)X(1/1000)= 0.132 m^3
- Volume of Water= ( Mass of Water/Specific gravity of water )X(1/1000)= (125/1)X(1/1000)= 0.125 m^3
- Volume of Chemical Admixture= ( Mass of Chemical Admixture/Specific gravity of chemical admixture )X(1/1000)= (7.6/1.145)X(1/1000)= 0.006 m^3
- Volume of aggregate (FA and CA)= (a-(b+c+d))= (1-(0.132+0.125+0.006))=0.737 m^3
- Mass of Coarse aggregate= eX Volume of coarse aggregate X Specific gravity of Coarse aggregate X 1000= 0.737 X 0.657 X 2.74 X 1000= 1327 kg/m^3
- Mass of Fine aggregate= e X Volume of fine aggregate X Specific gravity of fine aggregate X 1000= 0.737 X 0.343 X 2.74 X 1000= 693 kg/m^3
9. Mix proportions for Trial Number-1:
Cement= 417 kg/m^3
Water= 125 kg/m^3
Fine aggregate= 693 kg/m^3
Coarse aggregate= 1327 kg/ m^3
Chhemical admixture= 7 kg /m^3
Water-cement ratio= 0.30
Trial Mix ratio= 1 : 1.66 : 3.18