Project on Concrete Mix Design for various grades of Concrete

GRADE M35 with FLY ASH

AIM: Mix design for M35 Grade Concrete with fly ash.

PROCEDURE :

STEP 1 :

1. Grade designation: M35
2. Type of cement: OPC 43 Grade
3. Type of admixture: Fly Ash
4. Maximum nominal size of aggregate: 20 mm
5. Minimum cement content 320 kg/m^3
6. Maximum W/C ratio: 0.45
7. Workability: 100 mm slump value of pumpable concrete
8. Exposure condition: Severe
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

STEP 2

TEST DATA FOR MATERIALS

a) Cement used: OPC 53 Grade

b) Specific gravity of cement: 3.15

c) Chemical admixture: Super Plasticizer

d) Specific gravity of

1) Coarse aggregate 20mm : 2.67
2) Fine aggregate: 2.65
3) GGBS: 2.84

e) Water absorption:

1) Coarse aggregate : 0.5 %
2) Fine aggregate (M.sand) : 2.5 %

f) Free moisture:

1) Coarse aggregate: Nil
2) Fine aggregate: Nil

g) Sieve analysis:

1) Coarse aggregate: All in aggregates of Table 2 of IS 383
2) Fine aggregate: Grading Zone II of Table 4 of IS 383

STEP 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,
s = standard deviation.

From Table I of IS 10262:2009,

Standard Deviation, s = 5 N/mm^2.

Target strength = 35 + 1.65 x 5 = 43.25 N/mm^2.

STEP 4

SELECTION OF WATER CEMENT RATIO

Adopted maximum water-cement ratio = 0.41.

From Table 5 of IS 456 for Very severe Exposure

The maximum Water Cement Ratio is 0.45
0.41 < 0.45

Hence ok.

STEP 5

SELECTION OF WATER CONTENT

From Table 2 of IS 10262:2009,

Maximum water content for 20 mm aggregate = 186 liters (for 25 to 50 mm slump range)

Estimated water content for 100 mm slump = 186+ (6/186) = 197 litre.

Based on trials with Superplasticizer water content reduction of 20% has been achieved,

Hence the arrived water content = 197-[197 x (20/100)] = 158 liter.

STEP 6

CALCULATION OF CEMENT CONTENT

Adopted w/c Ratio = 0.41
Cement Content = 158/0.41 = 385 kg/m^3
From Table 5 of IS 456,

Minimum cement content for ‘Very severe’ exposure conditions 340kg/m^3

385 kg/m^3 > 340 kg/m^3

Hence ok.

STEP 7

PROPORTIO0N OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT

From Table 3 of (IS 10262:2009)

The volume of

Coarse aggregate corresponds to 20 mm size aggregate

Fine aggregate (Zone II) for a water-cement ratio of 0.50 =0.62.

In the present case,

The water-cement ratio is 0.41.

Therefore, the volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.06. The proportion of the 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, the correct proportion of the volume of coarse aggregate for the water-cement ratio of 0.44 = 0.64

For pumpable concrete, these values should be reduced up to 10%.

Therefore, volume of coarse aggregate =0.64 x 0.9 =0.576.

Volume of fine aggregate content = 1 – 0.576= 0.424.

STEP 8

MIX CALCULATIONS

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

a) Volume of concrete = 1 m^3

b) Volume of cement = [Mass of cement] / {[Specific Gravity of Cement] x 1000}
= 385/{3.15 x 1000}= 0.122 m^3

c) Volume of water = [Mass of water] / {[Specific Gravity of water] x 1000}
= 158/{1 x 1000}= 0.158m^3

d) Volume of chemical admixture = 1.54 litres/ m^3

e) Volume of all in aggregate = [a-(b+c+d)]
= [1-(0.122+0.158+0.004)]= 0.716 m^3

f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.716 x 0.576 x 2.67 x 1000= 1102 kg/m^3

g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
= 0.716 x 0.424 x 2.60 x 1000= 789 kg/m^3

STEP 8

MIX PROPORTIONS

Cement = 308 kg/m^3
GGBS = 77 kg/m^3
Water = 158 l/m^3
Fine aggregate = 789 kg/m^3

Coarse aggregate 20mm = 882 kg/m^3
12mm = 220 kg/m^3
Chemical admixture = 1.54 kg/m^3
Density of concrete = 2512 kg/m^3
Water-cement ratio = 0.41
Mix Proportion By weight = 1:2.04:2.86

RESULT

MIX PROPORTION = 1 : 2.04 : 2.86

MIX DESIGN FOR GRADE M50 without FLY ASH

AIM: Mix design for M50 Grade Concrete without Fly Ash

PROCEDURE :

STEP 1 :

1. Grade designation: M 50
2. Type of cement: OPC 53 grade
3. Maximum nominal size of aggregate: 20 mm
4. Minimum cement content : 360 kg/m^3
5. Maximum water-cement ratio: 0.35
6. Workability : 50-75 mm (slump)
7. Exposure condition: Extreme (for reinforced concrete)
8. Method of concrete placing: Pumping
9. Degree of supervision: Good
10. Type of aggregate: Crushed angular aggregate
11. Maximum cement content : 450 kg/m^3
12. Chemical admixture type: Super Plasticizer

Test Data for Materials

STEP 2:

Target Strength for Mix Proportioning

f_target = f_ck + 1.65 x s

f_target denotes the Target Average Compressive Strength at 28 days,

f_ck denotes the Characteristic Compressive Strength at 28 days,

‘s’ stands for Standard Deviation

standard deviation, s = 5.0 N/mm^2

Therefore, target strength = 50 + 1.65 x 5.0 = 58.25 N/mm^2

STEP 3

Selection of Water/Cement Ratio

From Table 5 of IS 456-2000,

Maximum water-cement ratio = 0.35

Selection of Water Content

From Table 2 of IS 456-2000, maximum water content =186 litres (for 25 to 50 mm slump range) for 20 mm aggregate.

Estimated water content for 100 mm slump =186+(6/100) x 186 =197 litres.

Based on trials with Super plasticizer water content reduction of 27% has been achieved,

Hence the arrived water content = 197 – [197 x (27/100)] = 143 litres.

STEP 4

Calculation of Cement Content

Water-cement ratio = 0.35

Cement content = 143/0.35 = 410 kg/m^3

From Table 5 of IS 456-2000,

minimum cement content for ‘Extreme exposure’ condition = 360 kg/m^3

410 kg/m^3 > 360 kg/m^3,

hence, O.K.

STEP 5

The proportion of Volume of Coarse Aggregate and Fine Aggregate Content

From Table 3 of IS 10262. the volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for a water-cement ratio of 0.50 =0.62.

In the present case, the water-cement ratio is 0.35.

Therefore. the volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.10. the proportion of the volume of coarse aggregate is increased by 0.02 (at the rate of -/+ 0.01 for every -/+ 0.05 change in the water-cement ratio).

Therefore. 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

STEP 6

Mix Calculations

a) Volume of concrete = 1m^3

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

= (410/3.12) X (1/1000) = 0.131 m^3

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

= (143/1) X (1/1000)= 0.143 m^3

d) Volume of Superplasticizer = (Mass of Superplasticizer / Specific gravity of admixture) X (1/1000)

= (8.2/1.145) X (1/1000)= 0.007 m^3

e) Volume of all aggregate = (a – (b + c + d))

= 1 – (0.131 + 0.143+0.007)= 0.719 m^3

e) 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

f) 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

STEP 7

Concrete Mix Proportions

1. Cement = 410 kg/m^3
2. Water = 143 kg/m^3
3. Super plasticizer = 7 kg/m^3
4. Fine aggregates = 763.86 kg/m^3
5. Coarse aggregate = 1152.48 kg/m^3
6. W/c = 0.35
7. Mix Proportion By weight = 1:2.28:3.12

RESULT

MIX PROPORTION = 1 : 2.28 : 3.12