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Project on Concrete Mix Design for various grades of Concrete

PPriyadevi P10 Jul 2022

Calculate the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash

1. Calculation of the Concrete Mix Design for M35 Grade Concrete with Fly Ash

Calculation of the mix design for M35 grade concrete with fly ash

Aim & Introduction:

To calculate the concrete Mix design for M35 grade concrete with fly ash.

Procedure:

Step 1: Data Collection

  1. Grade Designation = M35
  2. Type of Cement Used = OPC 53 Grade (As per IS 12269:1987)
  3. Type of Mineral Admixture = Fly Ash (As per IS 3812 Part-1)
  4. Max Nominal size of Aggregate = 20mm
  5. Min Cement Content = 340 Kg (As per Table-5 of IS456:2000)
  6. Max W/C ratio = 0.5 (As per Table-5 of IS456:2000)
  7. Workability = 100mm slump
  8. Exposure Condition = Severe (for reinforced concrete)
  9. Method of Concrete = Pumping
  10. Degree of Supervision = Good
  11. Type of Aggregate = Crushed Angular Aggregate
  12. Max Cement Content = 450 Kg/m3
  13. Chemical Admixture = Super plasticizer

Step 2: Test Data for Materials

  1. Cement Used = OPC 53 grade (As per IS 12269:1987)
  2. Specific Gravity of Cement = 3.15
  3. Fly Ash = IS 3812 Part-1
  4. Specific Gravity of Fly Ash = 2.7
  5. Chemical Admixture = Super Plasticizer (As per IS 9103)
  6. Specific Gravity of:
  • Coarse Aggregate = 2.74
  • Fine Aggregate = 2.74

vii. Water Absorption of:

  • Coarse Aggregate = 0.5%
  • Fine Aggregate = 1.0%

viii. Free Surface Moisture of:

  • Coarse Aggregate = Nil
  • Fine Aggregate = Nil

ix. Sieve Analysis of:

  • Coarse Aggregate = Table-2 of IS 383
  • Fine Aggregate = Table-4 of IS 383 (Zone II)

Step 3: Target Strength of Mix Proportioning

f’ck = fck+ (1.65 S)

Where,

f’ck = Target Compressive Strength at 28 days

fck = Compressive Strength at 28 days

S = Standard Deviation

From Table-1 of IS 10262:2009, S = 5 N/mm2

f’ck = 35 + (1.65 x 5)

f’ck = 43.25 N/mm2

Step 4: Selection of W/C ratio

From Table-5 of IS456:2000 for “severe” exposure condition

Max W/C ratio = 0.45

Adopted W/C ratio = 0.4

0.40 < 0.45

Hence, OK.

Step 5: Selection of Water Content

From Table-2 of IS 10262:2009

Max water content for 20mm size of aggregate = 186 lit (for 25 to 50 mm slump)

Water Content for 100mm slump = 186 + (6/100 x 186) = 197 lit

As super plasticizer is used, the water content can be reduced to 26%. Based on the trials water content reduction of 25% is achieved with plasticizers.

The Achieved Water Content = 197 x 0.75 = 147.75 lit ~ 145 lit

The achieved Water Content = 145 lit

Step 6: Calculation of Cement Content

W/C ratio = 0.4

Cementitious Material (Cement + Fly ash) = 145/0.4 = 363 Kg/m3

From Table-5 of IS 456:2000

Min Cement content for severe exposure condition = 340 Kg/m3

363 Kg/m3 > 340 Kg/m3

Hence, OK.

Step 7: Cement Mixing with Fly Ash

The % of fly ash needs to be decided based on the project requirement and quality.

In some cases, increase in cementitious material can be warrented. Increase in cementitious material content and its % may be based on experience and trial (Increase 10% of Fly ash).

Cementitious material content = 363 x 1.10 = 399 Kg/m3

Water Content = 145 Kg/m3

W/C ratio = 145/399 = 0.36

Fly ash @ 26% total cementitious material content = 399 x 26% = 104 Kg/m3

Cement (OPC) = 399 – 104 = 295 Kg/m3

Saving the cement while using fly ash = 363 – 295 = 68 Kg/m3

Fly ash being utilized = 104 Kg/m3

Step 8: Volume of Coarse Aggregate and Fine Aggregate

From Table-3 IS 10262:2009 for 20mm size of aggregate (Zone II) for w/c ratio of 0.5 = 0.6

In present w/c ratio = 0.4

Volume of coarse aggregate for w/c ratio 0.4 = 0.62

(For pumpable concrete this value reduced by 10%)

Volume of Coarse Aggregate = 0.62x 0.9 = 0.56

Volume of Fine Aggregate = 1 – 0.56 = 0.44

Step 9: Mix Calculations

(Per Unit Volume)

  1. Volume of Concrete = 1m3
  2. Volume of Cement = Mass of Cement / Specific Gravity of Cement

= (295 / 3.15) x (1 / 1000)

= 0.094 m3

3. Volume of Fly Ash = Mass of Fly ash / Specific Gravity of Fly ash

= (104 / 2.7) x (1 / 1000)

= 0.039 m3

4. Volume of Water = Mass of Water / Specific Gravity of Water

= (145 / 1) x (1 / 1000)

= 0.145 m3

5. Volume of Chemical Admixture = Mass of Chemical Admixture / Specific Gravity of Chemical Admixture

Mass of Chemical Admixture = 363x 2% of Super plasticizer = 7.26

Volume of Chemical Admixture = (7.26 / 1.145) x (1 / 1000) = 0.006 m3

6. Volume of Aggregate (FA & CA) = (a-(b+c+d+e))

= (1-(0.094+0.039+0.145+0.006))

= 0.716 m3

7. Mass of Coarse Aggregate= f x Volume of Coarse Aggregate x Specific Gravity of Coarse Aggregate x 1000

= 0.716 x 0.56 x 2.74 x 1000

= 1098 Kg/m3

8. Mass of Fine Aggregate = f x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000

= 0.716 x 0.56 x 2.74 x 1000

= 863 Kg/m3

Step 10: Mix Proportions

  • Cement = 295 Kg/m3
  • Fly Ash = 104 Kg/m3
  • Water = 145 Kg/m3
  • Fine Aggregate = 863 Kg/m3
  • Coarse Aggregate = 1098 Kg/m3
  • Chemical Admixture = 7.26
  • W/C ratio = 0.36

Trial Mix Ratio = Cement : Fly Ash : Fine Aggregate : Coarse Aggregate

1 : 0.35 : 2.92 : 3.72

Result:

Trial Mix Ratio = Cement : Fly Ash : Fine Aggregate : Coarse Aggregate

1 : 0.35 : 2.92 : 3.72

2. Calculation of the Concrete Mix Design for M50 Grade Concrete

Calculation of the mix design for M50 grade concrete

Aim & Introduction:

To calculate the concrete Mix design for M50 grade concrete.

Procedure:

Step 1: Data Collection

  1. Grade Designation = M50
  2. Type of Cement Used = OPC 53 Grade (As per IS 12269:1987)
  3. Max Nominal size of Aggregate = 20mm
  4. Min Cement Content = 360 Kg (As per Table-5 of IS456:2000)
  5. Max W/C ratio = 0.4 (As per Table-5 of IS456:2000)
  6. Workability = 75mm slump
  7. Exposure Condition = Extreme (for reinforced concrete)
  8. Method of Concrete = Pumping
  9. Degree of Supervision = Good
  10. Type of Aggregate = Crushed Angular Aggregate
  11. Max Cement Content = 450 Kg/m3
  12. Chemical Admixture = Super plasticizer

Step 2: Test Data for Materials

  1. Cement Used = OPC 53 grade (As per IS 12269:1987)
  2. Specific Gravity of Cement = 3.15
  3. Chemical Admixture = Super Plasticizer (As per IS 9103)
  4. Specific Gravity of:
  • Coarse Aggregate = 2.74
  • Fine Aggregate = 2.65

vii. Water Absorption of:

  • Coarse Aggregate = 0.5%
  • Fine Aggregate = 1.0%

viii. Free Surface Moisture of:

  • Coarse Aggregate = Nil
  • Fine Aggregate = Nil

ix. Sieve Analysis of:

  • Coarse Aggregate = Table-2 of IS 383
  • Fine Aggregate = Table-4 of IS 383 (Zone II)

Step 3: Target Strength of Mix Proportioning

f’ck = fck+ (1.65 S)

Where,

f’ck = Target Compressive Strength at 28 days

fck = Compressive Strength at 28 days

S = Standard Deviation

From Table-1 of IS 10262:2009, S = 5 N/mm2

f’ck = 50 + (1.65 x 5)

f’ck = 58.25N/mm2

Step 4: Selection of W/C ratio

From Table-5 of IS456:2000 for “Extreme” exposure condition

Max W/C ratio = 0.4

Hence, OK.

Step 5: Selection of Water Content

From Table-2 of IS 10262:2009

Max water content for 20mm size of aggregate = 186 lit (for 25 to 50 mm slump)

Water Content for 100mm slump = 186 + (3/100 x 186) = 192 lit

As super plasticizer is used, the water content can be reduced to 22%. Based on the trials water content reduction of 25% is achieved with plasticizers.

The Achieved Water Content = 192 x 0.78 = 150 lit

The achieved Water Content = 150 lit

Step 6: Calculation of Cement Content

W/C ratio = 0.4

Cement Content = 150/0.4 = 375 Kg/m3

From Table-5 of IS 456:2000

Min Cement content for severe exposure condition = 360 Kg/m3

375Kg/m3 > 360Kg/m3

Hence, OK.

Step 7: Volume of Coarse Aggregate and Fine Aggregate

From Table-3 IS 10262:2009 for 20mm size of aggregate (Zone II) for w/c ratio of 0.5 = 0.6

In present w/c ratio = 0.4

Volume of coarse aggregate for w/c ratio 0.4 = 0.62

(For pumpable concrete this value reduced by 10%)

Volume of Coarse Aggregate = 0.62x 0.9 = 0.56

Volume of Fine Aggregate = 1 – 0.56 = 0.44

Step 8: Mix Calculations

(Per Unit Volume)

  1. Volume of Concrete = 1m3
  2. Volume of Cement = Mass of Cement / Specific Gravity of Cement

= (375/ 3.15) x (1 / 1000)

= 0.12 m3

3. Volume of Water = Mass of Water / Specific Gravity of Water

= (150/ 1) x (1 / 1000)

= 0.15 m3

4. Volume of Chemical Admixture = Mass of Chemical Admixture / Specific Gravity of Chemical Admixture

Mass of Chemical Admixture = 375 x 2% of Super plasticizer = 7.5

Volume of Chemical Admixture = (7.5/ 1.145) x (1 / 1000) = 0.007 m3

5. Volume of Aggregate (FA & CA) = (1-(2+3+4))

= (1-(0.12+0.15+0.007))

= 0.723 m3

6. Mass of Coarse Aggregate= f x Volume of Coarse Aggregate x Specific Gravity of Coarse Aggregate x 1000

= 0.723 x 0.56 x 2.74 x 1000

= 1109 Kg/m3

7. Mass of Fine Aggregate = f x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000

= 0.723 x 0.44 x 2.65 x 1000

= 843 Kg/m3

Step 9: Mix Proportions

  • Cement = 375 Kg/m3
  • Water = 150 Kg/m3
  • Fine Aggregate = 843 Kg/m3
  • Coarse Aggregate = 1109 Kg/m3
  • Chemical Admixture = 7.5
  • W/C ratio = 0.4

Trial Mix Ratio = Cement : Fine Aggregate : Coarse Aggregate

1 : 2.2 : 3.0

Result:

Trial Mix Ratio = Cement : Fine Aggregate : Coarse Aggregate

1 : 2.2 : 3.0

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