Project on Concrete Mix Design for various grades of Concrete

Mix design for M35 grade :-

1. Stipulations for Mix Design Concrete

• Grade designation : M 35
• Type of cement : OPC 53 grade confirming to IS 8112
• Maximum nominal size of aggregate : 20 mm
• Minimum cement content : 340 kg/m³
• Maximum water-cement ratio : 0.45
• Workability : 50-100 mm (slump)
• Exposure condition : Very Severe (for reinforced concrete)
• Method of concrete placing : Pumping
• Degree of supervision : Good
• Type of aggregate : Crushed angular aggregate
• Maximum cement content : 450 kg/m³
• Chemical admixture type : Super Plasticizer

2. Test Data for Materials (to be determined in the laboratory)

• Specific gravity of cement : 3.12
• Specific gravity of Coarse aggregate : 2.74
• Specific gravity of Fine aggregate : 2.56

3. Target Strength for Mix Proportioning

f_target = f_ck + 1.65 x S

‘f_target‘ is the target average compressive strength at 28 days,

‘f_ck‘ is the characteristic compressive strength at 28 days, and

‘s’ is the standard deviation

As per the table I of IS: 10262-2009 , standard deviation, s = 5.0 N/mm²

Therefore, target strength = 35 + 1.65 x 5.0 = 43.25 N/mm²

4. Selection of Water/Cement Ratio

Maximum water-cement ratio = 0.45

5. Selection of Water Content

Estimated water content for 100 mm slump =186+(6/100) x 186 =197 liter.

6. Calculation of Cement Content

Water-cement ratio =0.45

Cement content = 147/0.45 = 350 kg/m³

7. The Proportion of the Volume of Coarse Aggregate and Fine Aggregate Content

In the present case, the water-cement ratio is 0.45. Therefore, the volume of coarse aggregate is required to be increased to reduce the fine aggregate content.

As the water-cement ratio is lower by 0.10, the proportion of the volume of coarse aggregate is increased by 0.02 (at the rate of -/+ 0.01 for every ± 0.05 change in the water-cement ratio). Therefore. the corrected proportion of the volume of coarse aggregate for the water-cement ratio of 0.45 = 0.63.

8. Mix Calculations

a) Volume of concrete = 1m³

b) Volume of cement = (Mass of cement/Specific Gravity of Cement) X (1/1000)

= (350/3.12) X (1/1000)

= 0.112 m³

c) Volume of water = (Mass of water/specific gravity of water) X (1/1000)

= (147/1) X (1/1000)

= 0.147 m³

d) Volume of superplasticizer = (Mass of superplasticizer / Specific gravity of admixture) X (1/1000)

= (7/1.145) X (1/1000)

= 0.006 m³

e) Volume of all aggregate = (a-(b+c+d))

= 1 – (0.112 + 0.147+0.006)

= 0.735 m³

f) Mass of coarse aggregate = Volume of all aggregate X volume of coarse aggregate X Specific gravity of coarse aggregate X 1000

= 0.735 x 0.567 x 2.74 x 1000

= 1141.88 kg

g)Mass of fine aggregate = Volume of all aggregate X volume of fine aggregate X Specific gravity of fine aggregate X 1000

= 0.735 x 0.433 x 2.56 x 1000

= 814.73 kg

9. Concrete Mix Proportions

• Cement = 350 kg/m³
• Water = 147 kg/m³
• Super plasticizer = 7 kg/m³
• Fine aggregates = 814.73 kg/m³
• Coarse aggregate = 1141.88 kg/m³
• W/c = 0.45