Project on Concrete Mix Design for various grades of Concrete

A) To Concrete Mix Design for M35 grade concrete with fly ash

Grade of concrete: M35

Type of cement: OPC 53 grade

Maximum nominal size of aggregate: 20 mm

Minimum cement content: 320 Kg/m3

Maximum water-cement ratio: 0.45

Workability: 50-75 mm (slump)

Exposure condition: severe

Degree of supervision: Good

Type of aggregate: Crushed angular aggregate

Maximum cement content: 450 kg/m3

2) Test Data for materials:

The specific gravity of cement: 3.15

The specific gravity of coarse aggregate: 2.74

Specific gravity of fine aggregate: 2.57

Water absorption in coarse aggregate: 0.5%

Water absorption in fine aggregate: 1%

Chemical admixture: super plasticizer

3) Target means Strength:

Ft = fck + 1.65 + S

Standard deviation, S taken as 5.0 N/mm2 (table 2 IS 10262:2019)

Target strength = 35+1.65*5.0=43.25 N/mm2

Selection of water-cement ratio:

From IS 456:2000

The maximum permissible water-cement ratio is 0.45

Selection of water content:

maximum water content = 186 liters ( for 25 to 50 mm slump range) for 20mm aggregate.

Estimated water content for 75 mm slump = 186+0.03*186=191.58 liters

Based on trials with super plasticizer water content reduction of 20% achieved hence, the assumed water content = 153.1

Calculation of cement content and fly ash:

Water-cement ratio = 0.45

Cement content = 153/0.45=340.58kg/m3

From table 5 of IS 456, the minimum cement content for severe exposure condition is 320kg/m3

It is 340.58kg/m3 which is greater than 320kg/m3

W/C ratio =153/375=.408

Fly ash 30% of the total material content = 375*30+112.5kg/m3

Cement =375-112.5=262.5kg/m3

Fly ash can be utilized = 112.5kg/m3

The proportion of the volume of coarse aggregate and fine aggregate content:

From table 3 of IS 10262:2000, the volume of course aggregate corresponding to 20mm size aggregate and fine aggregate for a water-cement ratio of 0.45=0.63

The pumbable concrete content =1-0.567=0.433

4) Mix Calculation:

1. a) Volume of concrete =1m3

b)Volume of cement= (mass of cement / specific gravity of the water)x(1/1000)

=(262.5/3.15)x(1/1000)

= 0.083 m3

Volume of fly ash = 112.2.2*0.001 = 0.0051m3

1. c) Volume of the water =(mass of water/specific gravity of the water)x(1/1000)

=(153/1)x(1/1000)

=0.153 m

1. Volume of super plasticizer = (mass of super plasticizer / specific gravity od admixture) X (1/1000)

=(6.81/1.145)x(1/1000)

=0.00594 m3

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

=1-(0.112+0.083+0.153+0.0594)

=0.65m3

1. Mass of the coarse aggregate

=0.65x0.567x2.74x1000

=1010kg

1. Mass of fine aggregate

=0.65x0.433x2.67x1000

=746.26kg

5) Concrete Mix proportions

Cement = 262.5kg/m3

Fly ash = 112.5kg/m3

water = 153kg/m3

Super plasticizer = 6.81kg/m3

Fine aggregate = 746 kg/m3

Coarse aggregate = 1010 kg/m3

W/C = 0.40

Result:

Mix proportion arrived: 1:2.18:3

B) The concrete mix design for M50 grade concrete without flyash:

1.step procedure

Grade designation : M50

Type of cement : OPC 53 grade

Maximum nominal size of aggregate : 20 mm

Minimum cement content : 320 kg/m3

Maximum water cement ratio : 0.45\

Workability : 50-75 mm (slump)

Exposure condition : 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:

The specific gravity of cement :3.15

The specific gravity of coarse aggregate :2.74

Specific gravityof the aggregate:2.67

Chemical admixture : superplasticizer to IS 9103

3.Target mean strength :

Ft = fck + 1.65 x 5

The standard deviation, S is taken as 5.0 N/mm2

Therefore,target strength = 50+1.65x5.0 = 58.25 N/mm2

Selection of water-cement ratio.

Assume water-cement ratio is 0.35

Selection off water cement:

From table 2 of IS 456:2000 , maximum water content = 186 littre

Estimated water content for 75 mm slump = 186+0.03x186 = 191.58 liters

Based on water content = 153 L

Calculation of cement content and Fly ash:

Water cement ratio = 0.35

Cement content = 153/0.35 = 437 kg/m3

From table 5 of IS 456 , the minimum cement content for”servere” exposure condition is 320kg.

It is 437kg/m3 which is greater than 320kg/m3 , hence it is ok

The proportion of volume of coarse aggregate and fine aggregate content:

From table 3 of IS 10262.2000, the volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate for water cement ration of 0.50=0.62

The corrected proportion of the volume of content aggregate for water cement ratio = 0.65

For pumpable concrete , these values should be reduced by 10 percent . Therefore , volume of coarse aggregate = 0.65x0.9=0.585

Volume of fine aggregate content = 1 – 0.567 = 0.415

4.Mix Calculations:

a)volume of concrete = 1m3

b)Volume of cement = (Mass of cement/specific gravity of cement ) x ( 1/1000)

= (437/3.15) x (1/1000)

=0.139 m3

c)Volume of water = ( mass of water / specific gravity ) x ( 1/1000)

=(153/1)x(1/1000)

=0.153m

1. Volume of superplasticizer = (mass of water/specific gravity of water)x (1/1000)

(153/1)x(1/1000)

=0.153 m

1. Volume of superplasticizer = (mass of superplasticizer / specific gravity of water)x(1/1000)

= (6.81/1.145)x(1/1000)

=0.70m3

1. Mass of coarse aggregate = volume of aggregate x volume of coarse aggregate x specific gravity of coarse aggregate x 1000

=1087kg

1. Mass of fine aggregate = volume of all aggregate x volume of fine aggregate x specific gravity x 1000

=0.70*0.4*2.67*1000

=810kg

5. Concrete mix proportion

Cement = 437 kg/m3

Water = 53kg/m3

Super plasticizer =6.81kg/m3

Fine aggregate = 810kg/m3

Coarse aggregate = 1087 kg/m3

W/C = 0.35

RESULT:

Mix proportion arrived = 1:1.8:2.5