Project on Concrete Mix Design for various grades of Concrete

Q1. Calculate the Concrete Mix Design for M50 grade concrete without Fly as

• Grade designation

1. Grade designation: M50
2. Type of cement: OPC 53 grade conforming to IS 8112
3. Maximum nominal size of aggregate: 20mm
4. Minimum cement content: 320kg/`m^3` (from TB 5 of IS 456:2000 exposure condition)
5. Maximum w/c ratio: 0.45 (from TB 5 of IS 456:2000 exposure condition)
6. Workability: 100mm (Slump value for pumpable concrete)
7. Exposure condition: Severe (for reinforced concrete)
8. Method of concrete placing: Pumping
9. Type of aggregate: Crushed angular
10. Degree of supervision: Good
11. Maximum cement content: 450 kg/`m^3`
12. Chemical admixtures: Super plasticizers

• Test data for materials

1. Specific gravity of F.A : 2.6
2. Specific gravity of C.A : 2.7
3. Cement used : OPC 53 grade confirming to IS 12269
4. Specific gravity of cement: 3.15

• Target strength for mix proportion:

f'ck= fck + 1.65s

s= 5 (From table 1 of 10262:2009)

f'ck = 50+(1.65`times`5) = 58.25 N/`mm^2`

• Selection of w/c ratio:

From table 5 of IS 456:2000 for severe exposure condition maximum water cement ratio= 0.45

Based on experience, we adopted w/c ratio = 0.40

Therefore, 0.40< 0.45 ......... Hence ok

• Selection of water content:

Maximum water content= 186 litre...... (from table 2 of IS 10262:2009)

for 100 mm slump,

water content= 186+((6%)`times`186) =197litre

Super plasticizers reduce 29% of water content

Hence new water content = 197 `times`0.71= 140 litre

• Calculation of cement content:

w/c ratio= 0.4

cement content= 140/0.4 = 350 kg/`m^3`

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

Hence ok

• Proportioning of volume of C.A & F.A content:

Volume of C.A for w/c ratio= 0.40 =0.62

Since the concrete is pumpable the volume of C.A is reduced by 10%

So, Volume of C.A= 0.62`times`0.9= 0.56

Therefore, Volume of F.A= 1-0.56= 0.44

• Mix calculation:

1. Volume of concrete 1`m^3`
2. Volume of cement= (Mass of cement/ Sp.gr of cement)`times`(1/1000)

= (350/3.15)`times`(1/1000)

= 0.111`m^3`

c. Volume of water= (Mass of water/ Sp.gr of water)`times`(1/1000)

= `(140/1)times(1/1000)` = 0.140`m^3`

d. Volume of chemical admixtures= (Mass of water/ Sp.gr of water)`times`(1/1000)

= `(7.6/1.145)`times`(1/1000)` = 0.0066 `m^3`

e. Volume of aggregate (F.A &C.A)= (a-(b+c+d))

= (1-(0.11+0.140+0.006) = 0.743 `m^3`

f. Volume of chemical admixtures= (Mass of water/ Sp.gr of water)`times`(1/1000)

= 0.743 `times`0.56 `times`2.7 `times`1000= 1123.41 kg/`m^3`

g. Mass of C.A = e `times`volume of C.A `times`sp.gr of C.A `times`1000

= 0.743`times`0.56`times`2.7`times`1000= 1123.41 kg/`m^3`

i. Mass of F.A = e `times`volume of F.A `times`sp.gr of F.A `times`100`

= 0.743`times`0.44`times`2.6`times`1000= 849.99 kg/`m^3`

• Mix proportions:

1. Cement : 350 kg/`m^3`
2. Water : 140kg/`m^3`
3. Fine aggregate : 850kg/`m^3`
4. Coarse aggregate : 1123.41kg/`m^3`
5. Chemical admixtures :7 kg/`m^3`
6. W/C ratio : 0.4

Q2. Calculate the Concrete Mix Design for M35 grade concrete with Fly ash

• Grade designation

1. Grade designation: M35
2. Type of cement: OPC 43 grade conforming to IS 8112
3. Maximum nominal size of aggregate: 20mm
4. Minimum cement content: 320kg/`m^3` (from TB 5 of IS 456:2000 exposure condition)
5. Maximum w/c ratio: 0.45 (from TB 5 of IS 456:2000 exposure condition)
6. Workability: 100mm (Slump value for pumpable concrete)
7. Exposure condition: Severe (for reinforced concrete)
8. Method of concrete placing: Pumping
9. Type of aggregate: Crushed angular
10. Degree of supervision: Good
11. Maximum cement content: 450 kg/`m^3`
12. Chemical admixtures: Super plasticizers
13. Type of mineral admixture: Fly ash confirming to IS 3812 (part 1)

• Test data for materials

1. Specific gravity of F.A : 2.6
2. Specific gravity of C.A : 2.7
3. Cement used : OPC 43 grade confirming to IS 8112
4. Specific gravity of cement: 3.15
5. Fly ash: Confirming to IS 3812 (Part 1)
6. Specific gravity of fly ash: 2.2
7. Chemical admixtures: Superplasticizers confirming to IS 9103

• Target strength for mix proportion:

f'ck= fck + 1.65s

s= 5 (From table 1 of 10262:2009)

f'ck = 35+(1.65`times`5) = 43.25 N/`mm^2`

• Selection of w/c ratio:

From table 5 of IS 456:2000 for severe exposure condition maximum water cement ratio= 0.45

Based on experience, we adopted w/c ratio = 0.40

Therefore, 0.40< 0.45 ......... Hence ok

• Selection of water content:

Maximum water content= 186 litre...... (from table 2 of IS 10262:2009)

for 100 mm slump,

water content= 186+((6%)`times`186) =197litre

Super plasticizers reduce 29% of water content

Hence new water content = 197 `times`0.71= 140 litre

• Calculation of cement content:

w/c ratio= 0.4

cement content= 140/0.4 = 350 kg/`m^3`

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

Hence ok

Now,

Cementitious material content= 350`times`1.10 = 385 kg/`m^3`

Water content = 140 kg/`m^3`

So, water cement ratio= 140/385= 0.364

Fly ash at 30% total cementitious material content= 385`times`30%= 115 kg/`m^3`

Cement (OPC) = 385-115= 270 kg/`m^3`

Saving of cement while using fly ash= 350-270= 80 kg/`m^3`

Fly ash being utilized= 115 kg/`m^3`

• Proportioning of volume of C.A & F.A content:

Volume of C.A for w/c ratio= 0.40 =0.62

Since the concrete is pumpable the volume of C.A is reduced by 10%

So, Volume of C.A= 0.62`times`0.9= 0.56

Therefore, Volume of F.A= 1-0.56= 0.44

• Mix calculation:

1. Volume of concrete 1`m^3`
2. Volume of cement= (Mass of cement/ Sp.gr of cement)`times`(1/1000)

= (270/3.15)`times`(1/1000)

= 0.0.085`m^3`

c. Volume of fly ash= (Mass of fly ash/ Sp.gr of fly ash)`times`(1/1000)

= `(115/2.2)times(1/1000)` = 0.0523`m^3`

d. Volume of water= (Mass of water/ Sp.gr of water)`times`(1/1000)

= `(140/1)times(1/1000)` = 0.140`m^3`

e. Volume of chemical admixtures= (Mass of water/ Sp.gr of water)`times` (1/1000) = `(7.6/1.145)`times`(1/1000) = 0.0066 `m^3`

f. Volume of aggregate (F.A &C.A)= (a-(b+c+d+e))

= (1-(0.086+0.052+0.140+0.006) = 0.716 `m^3`

g. Mass of Coarse aggregate (C.A) = e `times`volume of C.A `times`sp.gr of C.A `times`1000

= 0.716`times`0.56`times`2.7`times`1000= 1082.59 kg/`m^3`

h. Mass of Fine aggregate (F.A) = e `times`volume of F.A `times`sp.gr of F.A `times`100`

= 0.743`times`0.44`times`2.6`times`1000= 819.10 kg/`m^3`

• Mix proportions:

1. Cement : 350 kg/`m^3`
2. Fly ash : 115 kg/`m^3`
3. Water : 140kg/`m^3`
4. Fine aggregate : 819.10 kg/`m^3`
5. Coarse aggregate : 1082.59 kg/`m^3`
6. Chemical admixtures :7 kg/`m^3`
7. W/C ratio : 0.38