Project on Concrete Mix Design for various grades of Concrete

Answer-1 :-

Aim :- Mix Design for M35 Grade Concrete with Fly Ash.

• Stipulations for Proportioning :-

1. Grade designation : M35
2. Type of cement : OPC 53 Grade Conforming to IS 8112
3. Type of Admixture : Fly Ash Conforming 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 mm 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 : 45 kg/m³
13. Chemical admixture type : Fly Ash

• Test data for Material :-

1. Cement used : OPC 53 Grade
2. Specific gravity of cement : 3.15
3. Chemical admixture : Fly ash conforming to IS 12089 
4. Specific gravity of 
                 1) Coarse aggregate 20mm : 2.74
                 2) Fine aggregate : 2.74                          
5. Water absorption:    
                 1) Coarse aggregate : 0.5 %
                 2) Fine aggregate (M.sand) : 1 %                
6. Free (surface) moisture:    
                  1) Coarse aggregate : Nil (Absorbed Moisture also Nil)
                  2) Fine aggregate : Nil                 
7. Sieve analysis:        
                  1) Coarse aggregate: Conforming to all in aggregates of Table 2 of IS 383
                  2) Fine aggregate : Conforming to Grading Zone II of Table 4 of IS 383              

• Target Strength fo 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 = 0.45.

     From the Table 5 of IS 456 for Very severe Exposure maximum Water Cement Ratio is 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.

Based on trials with Super plasticizer water content reduction of 20% has been achieved.

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

Adopted Water Content = 160 L.

• Cement Content :-

Adopted w/c Ratio = 0.44
Cement Content = 160/0.45 = 356 kg/m³

Final Cementitious Content (Cement + Flyash) = 356*1.10

                                                                    =391.6 Kg
From Table 5 of IS 456, Minimum cement content for ‘Severe’ exposure conditions = 340kg/m³
= 391.6 kg/m³ > 340 kg/m³ hence ok.

Fly ash content requirement = 391.6*0.30

                                          = 117.48 = 118 Kg

Cement Content requirement = Cementious content - Fly ash

                                           = 391.6 - 117.48

                                           = 274.12

• Volume of Coarse aggregate and fine aggregates :-

From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 =0.62 .

In the present case water-cement ratio is 0.44. Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.06. 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 0.44 = 0.63.

 Therefore, volume of coarse aggregate =0.63.

Volume of fine aggregate content = 1 – 0.63= 0.37.

• Mix Calculations :-

The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete = 1 m³

b) Volume of cement = [Mass of cement] / [Specific Gravity of Cement] x 1000
                               = 275/{3.15 x 1000}
                               = 0.087 m³

C)Volume of Fly ash = [Mass of Fly ash] / [Specific Gravity of Fly ash] x 1000
                               = 118/{2.5 x 1000}
                               = 0.041 m³

d) Volume of water = [Mass of water] / [Specific Gravity of water] x 1000
                            = 160/{1 x 1000}
                            = 0.160 m³

e) Volume of chemical admixture = 0.71 litres/ m³ (By Trial and Error Method used 0.4% by the weight cement)

e) Volume of all in aggregate = [a-(b+c+de)]
                                           = [1-(0.087 +0.041+0.160+0.002)]
                                           = 0.71 m³

f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
                                        = 0.71*0.63 *2.74 *1000
                                        = 1225.6 Kg

g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
                                     = 0.71*0.37*2.74 *1000
                                     = 719.8 Kg

• Mix Proportions :-

Cement = 275 kg/m³
Water = 160 l/m³
Fine aggregate = 719.8 kg

Coarse aggregate 20mm =1226 kg
Chemical admixture = 7 kg/m³ (0.4% by the weight of cement)
Density of concrete = 2430 kg/m³
Water-cement ratio = 0.44

 Result :- Cement : Flyash: F.A : C.A : Water = 1 : 0.4 : 2.6 : 4.46 : 0.58

Answer-2 :- 

Aim :- Mix Design for M50 Grade Concrete.

• Stipulations for Proportioning :-

a) Grade designation : M50
b) Type of cement : OPC 43 Grade Conforming to IS 8112 
c) Maximum nominal size of aggregate : 20mm
d) Minimum cement content : 320 kg/m³ (IS 456:2000)
e) Maximum water-cement ratio : 0.45 (Table 5 of IS 456:2000)
f) Workability : 100 slump
g) Exposure condition : Severe (For Reinforced Concrete)
h) Method of concrete placing : Pumping
j) Degree of supervision : Good
k) Type of aggregate : Crushed Angular Aggregates
m) Maximum cement content : 450 kg/m³
n) Chemical admixture type : Super Plasticizer

• Test data for Material :-

a) Cement used : OPC 53 Grade Conforming to IS 8112 

b) Specific gravity of cement : 3.15

c) Chemical admixture : Super Plasticizer conforming to IS 9103 

d) Specific gravity of

         1) Coarse aggregate 20mm : 2.74
         2) Fine aggregate : 2.74

e) Water absorption:

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

f) Free (surface) moisture:

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

g) Sieve analysis:

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

• Target Strength fo 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 = 0.4.

  From the Table 5 of IS 456 for Very severe Exposure maximum Water Cement Ratio is 0.45.

  0.4 < 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 20% has been achieved.

Hence the arrived water content = 197-[197 x (29/100)] = 140 litre.

• Cement Content :-

Adopted w/c Ratio = 0.4
Cement Content = 140/0.4 = 350 kg/m³
From Table 5 of IS 456, Minimum cement content for ‘severe’ exposure conditions 320kg/m³
= 350 kg/m³ > 340 kg/m³ hence ok.

• Volume of Coarse aggregate and fine aggregates :-

From Table 3 of (IS 10262:2009) Volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio of 0.50 =0.6 .

In the present case water-cement ratio is 0.44. Therefore, volume of coarse aggregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.06. 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 0.44 = 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.

• Mix Calculations :-

The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete = 1 m^{3chrome://history/}

b) Volume of cement = [Mass of cement] / [Specific Gravity of Cement] x 1000
                               = 350 / {3.15 x 1000}
                               = 0.111 m³

c) Volume of water = [Mass of water] / [Specific Gravity of water] x 1000
                            = 140 / {1 x 1000}
                            = 0.140 m³

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

                                                 = (8.2/1.145) X (1/1000)

                                                 = 0.007 m³

e) Volume of all in aggregate = [a-(b+c+d)]
                                           = [1-(0.111+0.140+0.006)]
                                           = 0.743 m³

f) Mass of coarse aggregate= e x Volume of Coarse Aggregate x Specific Gravity of Fine Aggregate x 1000
                                        = 0.743x 0.576 x 2.74 x 1000
                                        = 1173 kg/m³

g) Mass of fine aggregate= e x Volume of Fine Aggregate x Specific Gravity of Fine Aggregate x 1000
                                     = 0.743x 0.424x 2.74 x 1000
                                     = 863 kg/m³

• Mix Proportions :-

Cement = 350 kg/m³
Water = 140 l/m³
Fine aggregate = 863 kg/m³ 

Coarse aggregate 20mm = 1173 kg/m³
Chemical admixture = 7 kg/m³ (0.4% by the weight of cement)
Density of concrete = 2430 kg/m³
Water-cement ratio = 0.4

Result :- Mix Proportion By weight = 1:2.46:3.35

Tables Used are

• Table : 8 of IS 10262
• Table : 5 of IS 456 : 2000
• Table : 8 of IS 10262 : 2009
• Table : 3 of IS 10262 : 2009