Project on Concrete Mix Design for various grades of Concrete

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

MIX PROPORTIONING OF CONCRETE M35 GRADE WITH FLY ASH

1. Grade designation :M35
2. Type of cement: OPC 43 grade conforming to IS 8112
3. Type of mineral admixture: Fly ash conforming to IS 3812 (part 1)
4. Maximum nominal size of aggregate:20mm
5. Minimum cement content:320 kg/m^3(from table 5 of IS 456:2000-Exposure condition)
6. Maximum water-cement ratio:0.45 (From table 5 of IS 456:2000-Exposure condition)
7. Workability:100 mm (slump value for pumpable concrete)
8. Exposure condition:severe (for reinforced concrete)
9. Method of concrete placing: Pumping
10. Degree of supervision: Good
11. Type of aggregate: Crushed angular aggregate
12. Maximum cement content: 450 kg/m^3
13. Chemical admixture type: Superplasticizer

2. TEST DATA FOR MATERIAlS:

1. cement: OPC 43 grade
2. Specific gravity of cement:3.15
3. Fly ash: conforming to IS 3812 (part 1)
4. Specific gravity of fly ash:2.2
5. Specific gravity of coarse aggregate:2.7
6. Specific gravity of fine aggregate:2.6
7. Water absorbtion of CA:0.5%
8. Water absorbtion of FA:1%
9. Moisture content of aggregate as per IS 2386(part3) for F.A &C.A:Nil.

3.TARGET STRENGTH for Mixing proportioning:

f'ck=fck+1.65*S

f'ck= target average compressive strength at 28days

fck=Characteristic compressive strength at 28 days

S= standard deviation

from the table1 of IS 10262:2009, standard deviation S=5N/mm^2

Therefore, Target strength=35+1.65*5=43.25N/mm^2

4.SELECTION OF WATER-CEMENT RATIO:

from the fig 1 IS 10262:2019, water-cement ratio required for the target strength of 43.25N/mm^2 is taken as 0.39 for OPC 43 grade curve. hence maximum water cement ratio is 0.45 as per table 5 IS 456:2000

0.39>0.45 we take the least W/C ratio is 0.39. Hence OK.

5.SELECTION OF WATER CONTENT:

From table 4 of IS 10262:2019

water content =186kg(for 50mm slump) for 20mm aggregate.Estimated water content for 100mm slump (increasing 3%for every 25mm slump)

=186+(6%*186)=197litres.

As the superplastisizers are used, the water content may be reduced upto 30% Based on trails water content reduction of 25% is achieved with plasticizer.

Hence the arrived water content=197*0.75=148litres.

6.CALCULATION OF CEMENT CONTENT:

water-cement ratio 0.39

cementious material(cement+fly ash)content=148/0.39=379kg/m^3

from table 5 of IS 456 2000 minimum cement content for severe exposure condition=320kg/m^3

379kg/m^3>320kg/m^3, hence ok.

Now to proportion a mix containing fly ash the following steps are suggested

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

2.In some cases increase in cementitious material can bewarrented. increase of cementitious material content and its percentage may be based on experience and trail( ths example is with increase of 10% cementitious material content)

Cementitious material content=379*1.10=417kg/m^3

water content=148kg/m^3

water cement ratio=148/417=0.354

Fly ash @ 30% total cementitious material content=417*30%=125kg/m^3

cement (OPC)=417-125=292kg/m^3

Saving cement using fly ash=379-125=254kg/m^3

fly ash being utilized=125kg/m^3

3.Proportion of volume of coarse aggregate and fine aggregate:

From Table 5 of IS 10262:2009, volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregatev (Zone 1) for water cement of 0.5=0.6

In present case the water cement ratio is 0.39

Therefore, the volume of coarse aggregate needs to be increased to decrease the fine aggregate content.

As the water-cement ratio is lower by 0.10,the proportion of volume of coarse aggregate is increased by 0.02( at the rate of -/+ 0.01 for every +/-0.05 change in water-cement ratio of 0.40=0.62

For the pumpable concrete these values are reduced by 10%

Therefore, volume of coarse aggregate=0.62*0.9=0.56

Volume of fine aggregate content=1-0.56=0.44.

7.MIX CALCULATIONS:

The mix calculations per unit volume of concrete shall be as follows:

a.Total volume of concrete=1m^3

b.Volume of cement= (Mass of cement/Specific gravity of cement)*(1/1000)

=(292/3.15)*(1/1000)=0.0926m^3

c.Volume of water=(Mass of water/Specific gravity of water)*(1/1000)

=(148/1)*(1/1000)=0.148m^3

d.Volume of fly ash=(Mass of fly ash/specfic gravity of fly ash)*(1/1000)

=(125/2.2)*(1/1000)=0.0568m^3

e.Volume of chemcal admixture( Superplastisizer)=(mass of chemical admixture/specific gravity of chemcal admixture)*(1/1000)= (292/0.01)*(1/1000)=0.00292m^3

f.Volume of all aggregates=(Volume ofconcrete)-(volume of cement+water+fly ash+chemical admixture)

= 1-(0.0926+0.148+0.0568+0.003711)

=0.698m^3

g.Mass of coarse aggregate=0.698*0.56*2.7*1000=1055kg/m^3

f.Mass of fine aggregate=0.698*0.44*2.6*1000=799kg/m^3

8.MIX PROPORTIONS:

Cement=292kg/m^3

Fly ash=125kg/m^3

Water content=148kg/m^3

Fine aggregate=799kg/m^3

Coarse aggregate=1055kg/m^3

Free water cement ratio=0.39

MIX PROPORTION FOR M35 GRADE CONCRETE=1:1.91:2.52.

MIX PROPORTIONS OF CONCRETE M50 GRADE WITHOUT FLY ASH

1.STIPULATIONS FOR PROPORTIONS:

1. Grade designation :M50
2. Type of cement: OPC 53 grade conforming to IS 8112
3. Type of mineral admixture: Fly ash conforming to IS 3812 (part 1)
4. Maximum nominal size of aggregate:20mm
5. Minimum cement content:320 kg/m^3(from table 5 of IS 456:2000-Exposure condition)
6. Maximum water-cement ratio:0.45 (From table 5 of IS 456:2000-Exposure condition)
7. Workability:100 mm (slump value for pumpable concrete)
8. Exposure condition:severe (for reinforced concrete)
9. Method of concrete placing: Pumping
10. Degree of supervision: Good
11. Type of aggregate: Crushed angular aggregate
12. Maximum cement content: 450 kg/m^3
13. Chemical admixture type: Superplasticizer

2.TEST DATA FOR MATERIALS:

1. cement: OPC 53 grade
2. Specific gravity of cement:3.15
3. Specific gravity of coarse aggregate:2.7
4. Specific gravity of fine aggregate:2.6
5. Water absorbtion of CA:0.5%
6. Water absorbtion of FA:1%
7. Moisture content of aggregate as per IS 2386(part3) for F.A &C.A:Nil.

3.TARGET STRENGTH FOR MIX PROPORTIONS:

f'ck=fck+1.65*S

f'ck= target average compressive strength at 28days

fck=Characteristic compressive strength at 28 days

S= standard deviation

from the table1 of IS 10262:2009, standard deviation S=5N/mm^2

Therefore, Target strength=50+1.65*5=58.25N/mm^2.

4.SELECTION OF WATER-CEMENT RATIO:

from the fig 1 IS 10262:2019, water-cement ratio required for the target strength of 58.25N/mm^2 is taken as 0.34 for OPC 53 grade curve. hence maximum water cement ratio is 0.45 as per table 5 IS 456:2000

0.34>0.45 we take the least W/C ratio is 0.34. Hence OK.

5.SELECTION OF WATER CONTENT:

From table 4 of IS 10262:2019

water content =186kg(for 50mm slump) for 20mm aggregate.Estimated water content for 100mm slump (increasing 3%for every 25mm slump)

=186+(6%*186)=197litres.

As the superplastisizers are used, the water content may be reduced upto 30% Based on trails water content reduction of 29% is achieved with plasticizer.

Hence the arrived water content=197*0.71=140litres.

6.CALCULATION OF CEMENT CONTENT:

water-cement ratio 0.34

Cement content=140/0.34=412kg/m^3

from table 5 of IS 456 2000 minimum cement content for severe exposure condition=320kg/m^3

412kg/m^3>320kg/m^3, hence ok.

7.SELECTION AND CALCULATION OF COARSE AND FINE AGGREGATES:

1.Proportion of volume of coarse aggregate and fine aggregate:

From Table 5 of IS 10262:2009, volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregatev (Zone 1) for water cement of 0.5=0.6

In present case the water cement ratio is 0.34

Therefore, the volume of coarse aggregate needs to be increased to decrease the fine aggregate content.

As the water-cement ratio is lower by 0.10,the proportion of volume of coarse aggregate is increased by 0.02( at the rate of -/+ 0.01 for every +/-0.05 change in water-cement ratio of 0.40=0.62

For the pumpable concrete these values are reduced by 10%

Therefore, volume of coarse aggregate=0.62*0.9=0.56

Volume of fine aggregate content=1-0.56=0.44.

7.MIX CALCULATIONS:

The mix calculations per unit volume of concrete shall be as follows:

a.Total volume of concrete=1m^3

b.Volume of cement= (Mass of cement/Specific gravity of cement)*(1/1000)

=(412/3.15)*(1/1000)=0.130m^3

c.Volume of water=(Mass of water/Specific gravity of water)*(1/1000)

=(140/1)*(1/1000)=0.140m^3

d.Volume of chemcal admixture( Superplastisizer)=(mass of chemical admixture/specific gravity of chemcal admixture)*(1/1000)= (412/0.01)*(1/1000)=0.00412m^3

e.Volume of all aggregates=(Volume ofconcrete)-(volume of cement+water+chemical admixture)

= 1-(0.130+0.140+0.00412)

=0.725m^3

f.Mass of coarse aggregate=0.725*0.56*2.7*1000=1096kg/m^3

g.Mass of fine aggregate=0.725*0.44*2.6*1000=829kg/m^3

8.MIX PROPORTIONS:

Cement=412kg/m^3

Water content=140kg/m^3

Fine aggregate=829kg/m^3

Coarse aggregate=1096kg/m^3

Free water cement ratio=0.34

MIX PROPORTION FOR M50 GRADE CONCRETE=1:2.01:2.66.