Project on Concrete Mix Design for various grades of Concrete

ANS :-

For M35 Grade

1. Type of Cement = OPC
2. Type of Admixture = Fly ash
3. Maximum Nominal Size of Aggregate = 20mm
4. Minimum Cement Content = 340kg ......................IS 456
5. Maximum Cement Content = 450kg ......................IS 456
6. Partial replacement of cement by Fly ash= 30% ................As per requirement
7. Maximum W/C ratio = 0.45
8. Workability =100mm
9. Water absorption
   Coarse aggregate = 0.5%
   Fine aggregate = 1%
10. Sieve Analysis
    Coarse aggregate = -
    Fine aggregate = Zone 2

• Target strength for mix proportion of M35 grade concrete
  Fck = fck+1.65s
  Fck = 35+1.65X5
  Fck = 43.25 N/mm2
• Selection of water cement ratio
  Maximum W/C ratio =0.45
  Adopted W/C ratio =0.45
• Selection of water content =186 liters
  The water content above is for a slump of 25 to 50 mm, but according to the specification our concrete requires a slump of 100 mm. Therefore, to get the desired slump, the water content must be increased. Clause 4.2 of IS1026 recommends increasing the water content by 3% to obtain an additional 25 mm slump. Therefore, to obtain a slump of 50 mm in addition to our concrete, the water content must be increased by 6%.
  Water-content for 100mm Slump = 186+(0.06*186) =197.16 liters
  As we use super plasticizers we can reduce the water content to gain strength in the concrete. The amount of water-content to be reduced depends on the type of super plasticizer.
  Percentage of Reduction in water content = 20%
  Water content requirement after Super Plasticizer = 198-(0.20X198) =157.73 liters
  Adopted Water Content = 160 liters
• Calculation of cement and fly ash content
  Adopted W/C ratio =0.45
  Total Cementitious (Cement +Fly ash) requirement = Water Content / WaterCement ratio
  = 160/0.45
  = 355.55 kg
  Here we have increased the cementitious content by 10%.
  Final Cementitious Content (Cement+Fly ash) = 356X1.10
  = 391.6 kg 0
  Minimum Cement Content required for ‘severe’ exposure= 340 kg .............................AS per IS 456
  Adopted Cementious content =391.6 kg > 340 kg
  Fly ash content requirement = 391.6X0.30 ..................30% replacement
  = 117.48~118 kg
  Cement Content requirement =Cementious content – Fly ash
  =391.6-117.48
  =274.12
  Calculation of Super Plasticiers @ 0.6 percent to the mass of cementitious content = = 391.6*(0.6/100) = 2.35 kg
• Coarse & Fine aggregate
  Coarse Aggregate ratio = 0.62 .................For W/c ratio =0.5
  Coarse Aggregate ratio for 0.45 w/c ratio = 0.63
  Final Fine Aggregate ratio = 0.37 .........................(1-0.63)=0.37
• Calculation of M35 Grade concrete

1. Volume of Concrete= 1 m3.
2. Total Volume of Cement =Cement/(Specific gravityX1000)
   = 275/(3.15X1000) =0.087 m3
3. Total Volume of Fly ash =Flyash/(Specific gravityX1000)
   =118/(2.5X1000) =0.041 m3
4. Volume of Water= Water /(Specific gravityX1000)
   =160/(1X1000) = 0.160 m3.
5. Volume of Superplasticizers = Superplasticizers /(Specific gravityX1000)
   =2.35/(1.12X1000) =0.002m3
6. Total Aggregates requirement = Volume of Concrete -(Total Volume of Cement+Total Volume of Fly ash+Volume of Water+Volume of Superplasticizers)
   =1 -(0.087 +0.041+0.160+0.002) = 0.71 m3
7. Coarse Aggregate (C.A)= Total Aggregates requirement X Coarse Aggregate ratio X Specific gravity X 1000
   =0.71X0.63X2.74X1000 =1225.6 kg
8. Fine Aggregate (F.A)= Total Aggregates requirement XFine Aggregate ratio X Specific gravity X 1000
   =0.71X0.37X2.74X1000 =719.8 kg

S.No.	MATERIALS	QUANTITY
1	Cement	275 kg
2	Flyash	118 kg
3	Fine Aggregate	720 kg
4	Coarse Aggregate (20mm)	1226 kg
5	WATER	160 L
6	PCE based SuperPlasticizer	2 L

For M50 Grade

• Grade designation : M 50
• Type of cement : OPC 53 grade confirming to IS 8112
• Maximum nominal size of aggregate : 20 mm
• Minimum cement content : 360 kg/m³
• Maximum water-cement ratio : 0.35
• Workability : 50-75 mm (slump)
• Exposure condition : Extreme (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

Test data for materials

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

Procedure for concrete mix design of M50 grade concrete

1. Target strength for mix proportioning=ftarget= fck+ 1.65 x Standard Deviation
   

   According to the table 1 of IS: 10262-2009 ,

   standard deviation, s = 5.0 N/mm2

   Target strength for mix proportioning=ftarget=50 + 1.65 x 5.0 = 58.25 N/mm2
   
2. Selection of water cement ratio
   Maxiumum water cement ratio= 0.35 ...................From IS 456
3. Selection of water content
   Maxiumum water content= 186liter ...................From IS 456 Table no. 2
   (for 25 to 50 mm slump range) for 20 mm aggregate.
   Maxiumum water content=186+(6/100) x 186 =197 litres.
   (for 25 to 50 mm slump range) for 20 mm aggregate.
   Based on Super plasticizer water content reduction of 27% has been achieved, Hence the arrived water content = 197 – [197 x (27/100)] = 143 litres.
4. Calaculation of cement content
   

   Water-cement ratio = 0.35

   Cement content = 143/0.35 = 410 kg/m3

   From Table 5 of IS 456, minimum cement content for ‘Extreme exposure’ condition = 360 kg/m³

   410 kg/m3 > 360 kg/m3, hence, O.K.

5. Coarse aggregate and fine aggregate content

   From Table 3 of IS 10262. volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for a water-cement ratio of 0.50 =0.62.

   In the present case, the water-cement ratio is 0.35. Therefore. the volume of coarse aggregate is required to be increased to decrease 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 0.35 = 0.65.

   For pumpable concrete, these values should be reduced by 10 percent.

   Therefore, volume of coarse aggregate = 0.65 x 0.9 = 0.585.

   Volume of fine aggregate content =1 – 0.585 =0.415

6. Mix calculation

• Volume of concrete = 1m³

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

  = (410/3.12) X (1/1000)

  = 0.131 m3

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

  = (143/1) X (1/1000)

  = 0.143 m3

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

  = (8.2/1.145) X (1/1000)

  = 0.007 m3

  Volume of all aggregate = ( Volume of concrete-(Volume of cement+Volume of Water+Volume of Superplasticizer)

  = 1 – (0.131 + 0.143+0.007)

  = 0.719 m3

  Mass of coarse aggregate = Volume of All Aggregate X Volume of Coarse Aggregate X Specific Gravity of Coarse Aggregate X 1000

  = 0.719 x 0.585 x 2.74 x 1000

  = 1152.48 kg

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

  = 0.719 x 0.415 x 2.56 x 1000

  = 763.86 kg

Concrete Mix Proportion

• Cement = 410 kg/m3
• Water = 143 kg/m3
• Super plasticizer = 7 kg/m3
• Fine aggregates = 763.86 kg/m3
• Coarse aggregate = 1152.48 kg/m3
• W/c = 0.35