Project on Concrete Mix Design for various grades of Concrete

AIM: To determine the mix design for M35 concrete with fly ash consisting of the following properties:

1. Grade designation : M35
2. Type of cement : OPC 43 Grade conforming IS 12269
3. Type of mineral admixture: Fly Ash confirming to IS 3812
4. Maximum nominal size of aggregate : 20mm
5. Minimum cement content : 320 kg/m3 (IS 456:2000)
6. Maximum water-cement ratio : 0.45 (Table 5 of IS 456:2000)
7. Workability : 100-120mm slump
8. Exposure condition : severe (For Reinforced Concrete)
9. Method of concrete placing : Pumping
10. Degree of supervision : Good
11. Type of aggregate : Crushed Angular Aggregates
12. Maximum cement content : 360 kg/m3
13. Chemical admixture type : Super Plasticizer ECMAS HP 890

TEST DATA FOR MATERIALS:

Cement used : OPC 43 Grade conforming IS 12269

Specific gravity of cement : 3.15

Fly Ash confirming to IS 3812: Specific gravity of fly ash= 2.2

Chemical admixture : Super Plasticizer conforming to IS 9103 (ECMAS HP 890)

Specific gravity of

Coarse aggregate 20mm : 2.74

Fine aggregate : 2.74

Water absorption:

Coarse aggregate : 0.5 %

Fine aggregate (M.sand) : 1 %

Free (surface) moisture:

Coarse aggregate : Nil (Absorbed Moisture also Nil)

Fine aggregate : Nil

Sieve analysis:

Coarse aggregate: Conforming to all in aggregates of Table 2 of IS 383

Fine aggregate : Conforming to Grading Zone I of Table 4 of IS 383

PROCEDURE:

A-3 TARGET STRENGTH FOR MIX PROPORTIONING

f’ck =fck + 1.65 s

where

f’ck = target average compressive strength at 28 days,

fck = characteristics compressive strength at 28 days, and

s = standard deviation.

From Table I of IS 10262:2009, Standard Deviation, s = 5 N/mm2. Therefore, target strength = 35 + 1.65 x 5 = 43.25 N/mm2.

* SELECTION OF WATER•CEMENT RATIO

Adopted maximum water-cement ratio = 0.40. From the Table 5 of IS 456 for severe Exposure maximum Water Cement Ratio is 0.45

0.40 < 0.45 Hence ok.

* SELECTION OF WATER CONTENT

From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 litre (for 25 to 50 mm slump range) Estimated water content for 100 mm slump = 186+ (6/186) = 197 litre.

(Note: If Super plasticizer is used, the water content can be reduced upto 20% and above.)

Based on trials with Super plasticizer water content reduction of 30% has been achieved, Hence the arrived water content = 197-[197 x (30/100)] = 132 litre.

Adopted water content= 140Litres.

*CALCULATION OF CEMENT CONTENT

Adopted w/c Ratio = 0.40.

Cement Content = 140/0.40 = 350 kg/m3

From Table 5 of IS 456, Minimum cement content for ‘Moderate’ exposure conditions= 320kg/m3

350 kg/m3 > 320 kg/m3 hence ok.

*Calculation of fly ash content:

Percentage of increase in cementetious material depends on requirement.

Increase by 10%

Cementitious content= 350*1.10=385kg/m^3

Fly ash @ 30% total cementetious content= 385*30/100=115kg/m^3

* PROPORTIO0N OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT

From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone I) for water-cement ratio of 0.50 =0.60 .

In the present case water-cement ratio is 0.40. Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.1. 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).

Therefore, corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.40 = 0.62

NOTE – In case the coarse aggregate is not angular one, then also volume of coarse aggregate may be required to be increased suitably based on experience & Site conditions.

For pumpable concrete these values should be reduced up to 10%. Therefore, volume of coarse aggregate =0.62x 0.9 =0.56

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

* MIX CALCULATIONS

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

1. a) Volume of concrete = 1 m3
2. b) Volume of cement = [Mass of cement] / {[Specific Gravity of Cement] x 1000}

= 270/{3.15 x 1000}

= 0.086m3

1. c) Volume of fly ash= [Mass of fly ash] / {[Specific Gravity of fly ash] x 1000}

=115/{2.2x1000)

=0.052m3

1. d) Volume of water = [Mass of water] / {[Specific Gravity of water] x 1000}

= 140/{1 x 1000}

= 0.140m3

1. e) Volume of chemical admixture = [Mass of chemical admixture] / {[Specific Gravity of Chemical admixture] x 1000}

=7.6/{1.145x1000}=0.006m3

1. f) Volume of all in aggregate = [a-(b+c+d+e)]

= [1-(0.086+0.052+0.140+0.006)]

= 0.716m3

1. g) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000

= 0.716x 0.56 x 2.74 x 1000

= 1098 kg/m3

1. h) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000

= 0.716x 0.44x 2.74 x 1000

= 863 kg/m3

RESULT:

MIX PROPORTIONS:

Cement = 270 kg/m3

Fly ash = 115 kg/m3

Water = 140 litres

Fine aggregate = 863kg/m3 Coarse aggregate 20mm = 1098 kg/m3

Chemical admixture = 7 kg/m3 (0.4% by the weight of cement)

Water-cement ratio = 0.40

Mix Proportion By weight = 1:2.24:2.85

CONCLUSION:

The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump on trial. The mix proportion shall be reworked for the actual water content and checked for durability requirements.

Two or more trials having variation of 10 % of water-cement ratio in Clause 10(Step 10) shall be carried out and a graph between three water-cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials. However, durability shall be met.

AIM: To determine mix design for M50 consisting the following properties:

1. Grade designation : M50
2. Type of cement : OPC 43 Grade conforming IS 12269
3. Maximum nominal size of aggregate : 20mm
4. Minimum cement content : 320 kg/m3 (IS 456:2000)
5. Maximum water-cement ratio : 0.45 (Table 5 of IS 456:2000)
6. Workability : 100-120mm slump
7. Exposure condition : severe (For Reinforced Concrete)
8. Method of concrete placing : Pumping
9. Degree of supervision : Good
10. Type of aggregate : Crushed Angular Aggregates
11. Maximum cement content : 360 kg/m3
12. Chemical admixture type : Super Plasticizer ECMAS HP 890

TEST DATA FOR MATERIALS

1. a) Cement used : OPC 43 Grade conforming IS 12269
2. b) Specific gravity of cement : 3.15
3. c) Chemical admixture : Super Plasticizer conforming to IS 9103 (ECMAS HP 890)
4. d) Specific gravity of

1) Coarse aggregate 20mm : 2.74

2) Fine aggregate : 2.74

1. e) Water absorption:

1) Coarse aggregate : 0.5 %

2) Fine aggregate (M.sand) : 1 %

1. f) Free (surface) moisture:

1) Coarse aggregate : Nil (Absorbed Moisture also Nil)

2) Fine aggregate : Nil

1. g) Sieve analysis:

1) Coarse aggregate: Conforming to all in aggregates of Table 2 of IS 383

2) Fine aggregate : Conforming to Grading Zone I of Table 4 of IS 383

* TARGET STRENGTH FOR MIX PROPORTIONING

f’ck =fck + 1.65 s

where

f’ck = target average compressive strength at 28 days,

fck = characteristics compressive strength at 28 days, and

s = standard deviation.

From Table I of IS 10262:2009, Standard Deviation, s = 5 N/mm2. Therefore, target strength = 50 + 1.65 x 5 = 58.25 N/mm2.

* SELECTION OF WATER•CEMENT RATIO

Adopted maximum water-cement ratio = 0.40. From the Table 5 of IS 456 for severe Exposure maximum Water Cement Ratio is 0.45

0.40 < 0.45 Hence ok.

* SELECTION OF WATER CONTENT

From Table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 litre (for 25 to 50 mm slump range) Estimated water content for 100 mm slump = 186+ (6/186) = 197 litre.

(Note: If Super plasticizer is used, the water content can be reduced upto 20% and above.)

Based on trials with Super plasticizer water content reduction of 30% has been achieved, Hence the arrived water content = 197-[197 x (30/100)] = 132 litre.

Adopted water content= 140Litres.

* CALCULATION OF CEMENT CONTENT

Adopted w/c Ratio = 0.40.

Cement Content = 140/0.40 = 350 kg/m3

From Table 5 of IS 456, Minimum cement content for ‘Moderate’ exposure conditions= 320kg/m3

350 kg/m3 > 320 kg/m3 hence ok.

*PROPORTIO0N OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT

From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone I) for water-cement ratio of 0.50 =0.60 .

In the present case water-cement ratio is 0.40. Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.1. 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).

Therefore, corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.40 = 0.62

NOTE – In case the coarse aggregate is not angular one, then also volume of coarse aggregate may be required to be increased suitably based on experience & Site conditions.

For pumpable concrete these values should be reduced up to 10%. Therefore, volume of coarse aggregate =0.62x 0.9 =0.56

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

* MIX CALCULATIONS

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

1. a) Volume of concrete = 1 m3
2. b) Volume of cement = [Mass of cement] / {[Specific Gravity of Cement] x 1000}

= 350/{3.15 x 1000}

= 0.111m3c) Volume of water = [Mass of water] / {[Specific Gravity of water] x 1000}

= 140/{1 x 1000}

= 0.140m3

1. d) Volume of chemical admixture = [Mass of chemical admixture] / {[Specific Gravity of Chemical admixture] x 1000}

=7.6/{1.145x1000}=0.006m3

1. e) Volume of all in aggregate = [a-(b+c+d)]

= [1-(0.111+0.140+0.006)]

= 0.743m3

1. f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000

= 0.743x 0.56 x 2.74 x 1000

= 1140 kg/m3

1. g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000

= 0.743x 0.44x 2.74 x 1000

= 896 kg/m3

RESULT:

MIX PROPORTIONS:

Cement = 350 kg/m3

Water = 140 litres

Fine aggregate = 896kg/m3 Coarse aggregate 20mm = 1140 kg/m3

Chemical admixture = 7 kg/m3 (0.4% by the weight of cement)

Water-cement ratio = 0.40

Mix Proportion By weight = 1:2.56:3.26

CONCLUSION:

The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump on trial. The mix proportion shall be reworked for the actual water content and checked for durability requirements.

Two or more trials having variation of 10 % of water-cement ratio in Clause 10(Step 10) shall be carried out and a graph between three water-cement ratios and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials. However, durability shall be met.