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Project on Concrete Mix Design for various grades of Concrete

MMirza Abdul Rahman Baig23 Apr 2022

Part A)

Required Data for calculating the quantities of concrete mix (some assumed)

  • Grade designation: M35
  • Type of Cement: OPC 43 grade
  • Typed of mineral admixture: Fly ash
  • Maximum nominal size of aggregate: 20 mm
  • Minimum cement content: 340 kg/m^3 (From table 5 of IS456:2000)
  • Maximum W/C ratio: 0.45
  • Workability: 75mm (Slump value for pumpable concrete)
  • Exposure condition: Very severe (RCC)
  • Method of concrete placing: Pumping
  • Degree of supervision: Good
  • Type of aggregate: Crushed angular aggregate
  • Maximum cement content: 450 kg/m3
  • Chemical admixture type: Superplasticizer
  • Considering the zone I of aggregates from the table 3 of IS: 10262

Test data for materials:

  1. Cement used: OPC 43 grade conforming to IS 8112
  2. The specific gravity of cement: 3.15
  3. Fly ash: Conforming to IS 3812 (Part 1)
  4. The specific gravity of fly ash: 2.21
  5. Chemical admixture: Superplasticizer conforming to IS 9103
  6. The specific gravity of:
  • Coarse aggregate: 2.75
  • Fine aggregate:2.75
  1. Water absorption:
  • Coarse aggregate: 0.5%
  • Fine aggregate: 1.0%
  1. Free surface moisture:
  • Coarse aggregate: Nil
  • Fine aggregate: Nil

Fine aggregate: Conforming to grading zone I of table 4 of IS 383

III. Target Strength for Mix proportioning:

  • f’ck= fck + 1.65*S
  • From table 1 of IS 10262: 2009, Standard deviation, S=5 N/mm2
  • Therefore, Target strength = 35+1.65*5 = 43.25 N/mm2

IV: Selection of W/C ratio:

  • From table 5 of IS: 456: 2000 for very severe exposure, maximum W/C ratio = 0.45
  • Based on experience, adopt w/c ratio as 0.42 < 0.45, Hence Ok
  • Selection of W/C ratio
  • From Table 2 of IS 10262: 2009, maximum W/C content for 20mm aggregate = 186 litre (for 25mm to 50mm slump range)
  • Estimated Water content for 75mm slump = 186+3/100*186=191.58 litres
  • As a superplasticizer is used, the water content can be reduced by up to 30%
  • Based on trials water content reduction of 28% is achieved with plasticizer
  • Hence the arrived water content = 191.58*.72=137.94 litres

VI: Calculation of Cement content:

W/C ratio= 0.42

Cementitious Material (Cement+ Fly ash) Content = 137.94/0.42=328.423 kg/m^3

From the table 5 of IS 456 minimum cement content for very severe exposure condition = 340kg/m^3. Therefore, adopting 340kg/m^3 as the required content. Hence OK

Steps to calculate the proportion of cement content.

  1. Considering 10% of Cementitious material content = 340 x 1.1= 374 kg/m^3
  2. Water content = 137.94 litres
  3. W/C = 94/374= 0.369
  4. Fly ash @ 30% of total cementitious material content = 374 x 30% = 112.2kg/m^3
  5. Cement = 374-112.2 =216.8 kg/m^3
  6. Cement Savings = 340-216.8 = 123.2 kg/m^3
  7. Fly ash being utilised = 112.2 kg/m^3

VIII. Mix calculations:

The mix calculation per unit volume per unit volume of concrete shall be as follows.

  1. Volume of concrete = 1m^3
  2. Volume of cement = 216.8/3.15*1/1000= 0.06882 m^3
  3. Volume of Fly ash = 112.2/2.21*1/1000 = 0.05077 m^3
  4. Volume of water = 137.94/1 x 1/1000 =0.13794 m^3
  5. Volume of chemical admixture = 7.6/1.145 x 1/1000= 6.63755x 10^-3
  6. Volume of aggregate (FA & CA) = (a-(b+c+d+e))= (1-(0.06882+0.05077+0.13794+0.0063755)) = 0.716 m^3
  7. From table 3 of IS 10262 for zone I = 0.6 for 20mm aggregate
  8. Volume Reduction for pumpable concrete 10% reduction 20mm size aggregate = 0.6 x 0.9 = 0.54
  9. Mass of coarse aggregate = f x Volume of coarse aggregate x specific gravity of coarse aggregate x 1000 = 0.716 x 0.54 x 2.75 x 1000 = 1063.26 kg/m^3
  10. Mass of fine aggregate = f x Volume of fine aggregate x Specific gravity of fine aggregate x 1000 = 0.716 x 0.46 x 2.75 x 1000 = 905.74 kg/m^3

IX) Mix proportions for trial number 1:

  • Cement = 216.8 kg/m^3
  • Fly ash = 112.22 kg/m^3
  • Water = 137.94 litres
  • Fine aggregates = 905.74 kg/m^3
  • Coarse aggregates = 1063.26kg/m^3
  • Chemical admixtures = 7 kg/m^3
  • W/C ratio = 0.369

Mix Ratio: 1: 4.178: 4.904

Part B)

Required Data for calculating the quantities of concrete mix (some assumed)

Grade designation: M50

Type of Cement: OPC 43 grade

Typed of mineral admixture: Nil

Maximum nominal size of aggregate: 20 mm

Minimum cement content: 340 kg/m^3 (From table 5 of IS456:2000)

Maximum W/C ratio: 0.4

Workability: 75mm (Slump value for pumpable concrete)

Exposure condition: Very severe (RCC)

Method of concrete placing: Pumping

Degree of supervision: Good

Type of aggregate: Crushed angular aggregate

Maximum cement content: 450 kg/m3

Chemical admixture type: Superplasticizer

Test data for materials:

Cement used: OPC 43 grade conforming to IS 8112

The specific gravity of cement: 3.15

Chemical admixture: Superplasticizer conforming to IS 9103

The specific gravity of:

  • Coarse aggregate: 2.75
  • Fine aggregate:2.75

Water absorption:

  • Coarse aggregate: 0.5%
  • Fine aggregate: 1.0%

Free surface moisture:

  • Coarse aggregate: Nil
  • Fine aggregate: Nil

Fine aggregate: Conforming to grading zone I of table 4 of IS 383

III. Target Strength for Mix proportioning:

  • f’ck= fck + 1.65*S
  • From table 1 of IS 10262: 2009, Standard deviation, S=5 N/mm2
  • Therefore, Target strength = 50+1.65*5 = 58.25 N/mm2

IV: Selection of W/C ratio:

  • From table 5 of IS: 456: 2000 for very severe exposure, maximum W/C ratio = 0.4
  • Based on experience, adopt w/c ratio as 0.4 < =0.4, Hence Ok
  1. Selection of W/C ratio
  • From Table 2 of IS 10262: 2009, maximum W/C content for 20mm aggregate = 186 litre (for 25mm to 50mm slump range)
  • Estimated Water content for 75mm slump = 186+3/100*186=191.58 litres
  • As a superplasticizer is used, the water content can be reduced by up to 30%
  • Based on trials water content reduction of 28% is achieved with plasticizer
  • Hence the arrived water content = 191.58*.72=137.94 litres

VI: Calculation of Cement content:

  • W/C ratio = 0.4
  • Cementitious Material (Cement) Content = 137.94/0.4=344.85 kg/m^3

From table 5 of IS 456 minimum cement content for very severe exposure conditions = 340kg/m^3. Therefore, adopting 344.85 kg/m^3 as the required content. Hence OK

Steps to calculate the proportion of cement content.

  • Considering Cement material content = 344.85 kg/m^3
  • Water content = 137.94 litres
  • W/C =137.94/344.85= 0.4

VIII. Mix calculations:

The mix calculation per unit volume of concrete shall be as follows.

  • Volume of concrete = 1m^3
  • Volume of cement = 344.85/3.15*1/1000= 0.10947 m^3
  • Volume of water = 137.94/1 x 1/1000 =0.13794 m^3
  • Volume of chemical admixture = 7.6/1.145 x 1/1000= 6.63755x 10^-3
  • Volume of aggregate (FA & CA) = (a-(b+c+d+e))= (1-(0.10947+0.13794+0.0063755)) = 0.7462 m^3
  • From table 3 of IS 10262 for zone I = 0.6 for 20mm aggregate
  • Volume Reduction for pumpable concrete 10% reduction 20mm size aggregate = 0.6 x 0.9 = 0.54
  • Mass of coarse aggregate = f x Volume of coarse aggregate x specific gravity of coarse aggregate x 1000= 0.7462 x 0.54 x 2.75 x 1000 = 1108.107 kg/m^3
  • Mass of fine aggregate = f x Volume of fine aggregate x Specific gravity of fine aggregate x 1000 = 0.7477 x 0.46 x 2.75 x 1000 = 943 kg/m^3
  1. IX) Mix proportions for trial number 1:
  • Cement = 344.85 kg/m^3
  • Water = 137.94 litres
  • Fine aggregates = 943.943 kg/m^3
  • Coarse aggregates = 1108.107 kg/m^3
  • Chemical admixtures = 7 kg/m^3
  • W/C ratio = 0.4057

Mix Ratio, M50: 1: 2.737 : 3.2133

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