Project on Concrete Mix Design for various grades of Concrete

1. To calulate the concrete mix design for M35 grade with fly ash.

Intrduction ;

grade designation - M35

type of cement - OPC 43 grade

Maximum nominal size of aggregate - 20mm

Nominal admixture - fly ash

plasticizer-chemical admixture

STEP 1:TO FIND TARGET STRENGTH FOR MIX PROPORTIONING

target mean strength

f'ck=fck + 1.65 S

=35+1.65(5.0)

f'ck = 43.25 N/mm^2

2. SELECTION OF WATER-CEMENT RATIO

Water cement ratio = 0.38

severe condition = 0.45

from the graph 2 -2019

we can consider lowest value=0.45

3.selection of cement

slump value=75 mm

• From Table 2 of IS 456, maximum water content =186 litres (for 25 to 50 mm slump range) for 20 mm aggregate.
• Clause 4.2 suggests increasing of 3% of water content for every extra 25mm slump from 50mm slump.

=186(3/186)

=191.6 L

• If Super plasticizer is used, the water content can be reduced up to 20% or 30% and above.

30% percent is reduced because of super plastisicer

=134.12 litres

4. Calculation of cement content

cementatious =353x1.1=388 kg

fly ash = 30% of 388 kgs

=119.4 kg

to find cement content=388-116.4 kgs

=271.6 kgs

=134/388

=0.34

5.Aggregate and fine aggregate

Formulae (0.5-w\c/0.05x0.01)+volume

=(0.5-0.38/0.05x0.01)+0.60

=0.624

for pumpable concrete reduce 0.624 into 10%

coarse aggregate = 0.562

coarse aggregate + fine aggregate = total aggregate

CA+FA=1

so

(1-coarse aggregate)

coarse aggregate =0.562

fine aggregate =0.438

6. Mix calculation

a) Volume of concrete = 1m^3

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

=271/3.15 x (1/1000)

=0.086 m^3

7.volume of fly ash

Volume of fly ash = [Mass of fly ash / Specific Gravity of fly ash] x 1/1000

=116/2.2)x1/1000

=0.052 m^3

8.Mass of water

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

=134/10.052)x1/1000

=0.134

9.Chemical admixture

volume of chemical admixture = [Mass of admixture] / [Specific Gravity of admixture] x 1/1000

=7.76/1.145x1/1000

=0.006 m^3

10.Volume of all aggregate

= (a-(b+c+d))

=1-(0.086+0.052+0.134)

=0.772m^3

11.Mass of coarse aggregate = Volume of all aggregate X volume of coarse aggregate X Specific gravity of coarse aggregate X 1000

=0.772x0.562x2.74x1000

= 1111.8 kg/m^3

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

=0.772x0.438x2.46x1000

=832 kg/m^3

13.Concrete mix proposion

cement=271 kg/m^3

water=134 litres

fine aggregate=1111.8 kg/m^3

coarse aggregate=832 kg/m^3

RATIO

271:832:1111

Therefore the mix ratio with fly ash is = 1:3.07:4.09

2.M50 grade of concrete without fly ash

1. To calulate the concrete mix design for M50 grade .

Intrduction ;

grade designation - M50

type of cement - OPC 53 grade

Maximum nominal size of aggregate - 20mm

STEP 1:TO FIND TARGET STRENGTH FOR MIX PROPORTIONING

target mean strength

f'ck=fck + 1.65 S

=50+1.65(5.0)

f'ck = 58.25 N/mm^2

2. SELECTION OF WATER-CEMENT RATIO

Water cement ratio = 0.35

we can consider lowest value=0.35

3.selection of water content

slump value=100 mm

• From Table 2 of IS 456, maximum water content =186 litres (for 25 to 50 mm slump range) for 20 mm aggregate.
• Clause 4.2 suggests increasing of 3% of water content for every extra 25mm slump from 50mm slump.

=186(6/186)

=197 L

• If Super plasticizer is used, the water content can be reduced up to 20% or 30% and above.

27% percent is reduced because of super plastisicer

= 197 – [197 x (27/100)] = 143 litres.

=143 litres

4. Calculation 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/m^3

=360 kg/m3

5.Aggregate and fine aggregate

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

a) Volume of concrete = 1m^3

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

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

= 0.131 m^3

7.Mass of water

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

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

=0.143 m^3

8.Chemical admixture

volume of chemical admixture = [Mass of admixture] / [Specific Gravity of admixture] x 1/1000

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

=0.007 m^3

9.Volume of all aggregate

= (a-(b+c+d))

= 1 – (0.131 + 0.143+0.007)

=0.719m^3

10.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 kg/m^3

11.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/m^3

12.Concrete mix proposion

cement=410 kg/m^3

water=143 litres

fine aggregate=763.86 kg/m^3

coarse aggregate=1152.48 kg/m^3

RATIO

410:764:1153

Therefore the mix ratio with fly ash is = 1:1.86:2.81