Project on Concrete Mix Design for various grades of Concrete

1] Stipulation for proportioning

Grade designation = M35

Type of cement = OPC 43 grade conforming to IS 8112

Type of mineral admixture = fly ash conforming to IS3812 (part 1)

Maximum nominal size of aggregate = 20mm

Minimum cement content = 340 kg/m3 (from table 5 of IS 456:2000 - Exposure condition)

Maximum water-cement ratio = 0.45 (from table 5 of IS 456:2000 - Exposure condition)

Workabilty = 100mm (slump value for pumpable concrete)

Exposure condition = very sever (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 = Superplasticizer

Test data for material:

Cement used = OPC 43 grade conforming to IS 8112

Specific gravity of cement = 3.15

Fly ash = conforming to IS 3812 (part 1)

Specific gravity of fly ash = 2.2

Chemical admixture = Superplasticizer conforming to IS 9103

Specific gravity of : Coarse aggregate = 2.74

Fine aggregate = 2.74

Water absorption : Coarse aggregate = 0.5%

Fine aggregate = 1.0%

Free surface moisture : Coarse aggregate = Nil

Fine aggregate = Nil

Sieve analysis: Coarse aggregate = conforming to table 2 of IS 383

Fine aggregate = conforming to grade zone 1 of table 4 of IS 383

• Target Strength for mix proportioning

f'ck=fck + 1.65s

= 35 + 1.65x5

= 43.25 N/mm2

• Selection of water cement ratio :

from table 5 of IS 456:2000 for very sever maximum water cement ratio = 0.45

Based on experience adopt w/c as 0.4

0.4<0.45 Hence Ok

• Selection of water content :

from table 2 of IS 10262:2009, maximum water content for 20mm aggregate = 186 litre (for 25mm to 50mm slump range)

Estimated water content for 100mm slump = 186+6/100X186 = 197 litre

based of trials water content reduction of 29% is achieved with plasticizer

hence, the arrived water content = 197X0.71 = 140 litre

• Calculation of cement content :

water cement ratio = 0.4

cementitious material ( cement + fly ash ) content = 140/0.4 = 350 kg/m3

from table 5 of IS 456 maximum cement content for ' very severe' exposure condition = 340 kg/m3

350kg/m3 >340kg/m3

(This example is with increase of 10% cementitious material content )

Cementitious material content = 350X1.1 = 385kg/m3

water content = 140kg/m3

water cement ratio = 140/385 = 0.364 fly ash @30% total cementitious material content = 385X30% = 115kg/m3

cement (OPC) = 385-115 = 270kg/m3

Saving of cement while using fly ash = 350-270 = 80kg/m3

fly ash being utilized = 115kg/m3

In present case the w/c ratio is 0.4 corrected volume of coarse aggregate for the w/c ratio of 0.4=0.62

for pumpable concrete these values are redused by 10%

:- volume of coarse aggregate = 0.62x0.9 = 0.56

volume of fine aggregate content = 1-0.56 = 0.44

• Mx Proportions:

1. Volume of concrete = 1m3
2. Volume of cement = mass of cemenr/specific gravity of cement X 1/1000 = 270/3.15 X1/1000 = 0.086m3
3. Volume of fly ash = mass of fly ash/specific gravity of fly ash X 1/1000 = 115/2.2 X1/1000 = 0.052m3
4. volume of water = mass of water/specific gravity of water X 1/1000 = 140/1 X1/1000 = 0.140m3
5. Volume of chemical admixture = mass of chemical admixture/specific gravity of chemical admixture X 1/1000 = 7.6/1.145X1/1000 = 0.006m3
6. Volume of aggregate (FA & CA) = (a-(b+c+d+e)) = (1-(0.086+0.052+0.140+0.006)) = 0.716m3
7. Mass of coarse aggregate = f x volume of coarse aggregate x specific gravity of coarse aggregate x 1000 = 0.716 x 0.56 x 2.74 x 1000 = 1098 kg/m3
8. Mass of fine aggregate = f x volume of fine aggregate x specific gravity of fine aggregate x 1000 = 0.716 x 0.44 x 2.74 x 1000 = 863 kg/m3

MIX PROPORTION FOR TRIAL NUMBER1

Cement = 270 kg/m3

Fly ash = 115 kg/m3

Water = 140 kg/m3

Fine aggregate = 863 kg/m3

Coarse aggregate = 1098 kg/m3

Chemical admixture = 7 kg/m3

Water cement ratio = 0.364

Trial mix ratio = 1:2.24:2.85

2] Stipulation for proportioning

Grade designation = M50

Type of cement = OPC 53 grade conforming to IS 12269 - 1987

Minimum cement content = 320 kg/m3 (from table 5 of IS 456:2000 - Exposure condition)

Maximum water-cement ratio = 0.45 (from table 5 of IS 456:2000 - Exposure condition)

Workabilty = 100mm (slump value for pumpable concrete)

Exposure condition = sever (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 = Superplasticizer

Test data for material:

Cement used = OPC 53 grade conforming to IS 12269 - 1987

Specific gravity of cement = 3.15

Chemical admixture = Superplasticizer conforming to IS 9103

Specific gravity of : Coarse aggregate = 2.74

Fine aggregate = 2.64

Water absorption : Coarse aggregate = 0.5%

Fine aggregate = 1.0%

Free surface moisture : Coarse aggregate = Nil

Fine aggregate = Nil

Sieve analysis: Coarse aggregate = conforming to table 2 of IS 383

Fine aggregate = conforming to grade zone 1 of table 4 of IS 383

• Target Strength for mix proportioning

f'ck=fck + 1.65s

= 53 + 1.65x5

= 58.25 N/mm2

• Selection of water cement ratio :

from table 5 of IS 456:2000 for very sever maximum water cement ratio = 0.45

Based on experience adopt w/c as 0.44

0.44<0.45 Hence Ok

• Selection of water content :

from table 2 of IS 10262:2009, maximum water content for 20mm aggregate = 186 litre (for 25mm to 50mm slump range)

Estimated water content for 100mm slump = 186+6/100X186 = 197 litre

based of trials water content reduction of 20% is achieved with plasticizer

hence, the arrived water content = 197X0.8 = 158 litre

• Calculation of cement content :

water cement ratio = 0.44

cement content = 158/0.44 = 359 kg/m3

from table 5 of IS 456 maximum cement content for ' very severe' exposure condition = 340 kg/m3

359kg/m3 >320kg/m3

In present case the w/c ratio is 0.44 corrected volume of coarse aggregate for the w/c ratio of 0.44=0.632

for pumpable concrete these values are redused by 10%

:- volume of coarse aggregate = 0.632x0.9 = 0.568

volume of fine aggregate content = 1-0.568 = 0.43

• Mx Proportions:

1. Volume of concrete = 1m3
2. Volume of cement = mass of cemenr/specific gravity of cement X 1/1000 = 359/3.15 X1/1000 = 0.114m3
3. volume of water = mass of water/specific gravity of water X 1/1000 = 158/1 X1/1000 = 0.158m3
4. Volume of chemical admixture = mass of chemical admixture/specific gravity of chemical admixture X 1/1000 = 7.6/1.145X1/1000 = 0.006m3
5. Volume of aggregate (FA & CA) = (a-(b+c+d)) = (1-(0.114+0.158+0.006)) = 0.722m3
6. Mass of coarse aggregate = f x volume of coarse aggregate x specific gravity of coarse aggregate x 1000 = 0.722 x 0.568 x 2.74 x 1000 = 1123 kg/m3
7. Mass of fine aggregate = f x volume of fine aggregate x specific gravity of fine aggregate x 1000 = 0.722 x 0.431 x 2.74 x 1000 = 821 kg/m3

MIX PROPORTION FOR TRIAL NUMBER1

Cement = 359 kg/m3

Water = 158 kg/m3

Fine aggregate = 821 kg/m3

Coarse aggregate = 1123 kg/m3

Chemical admixture = 7.18 kg/m3

Water cement ratio = 0.44

Trial mix ratio = 1:2.28:3.12