Project on Concrete Mix Design for various grades of Concrete

1. Concrete Mix Design for M35 grade concrete with fly ash :-

Solution :

• Stipulations for Proportioning
  1. Grade Designation : M35
  2. Type of Cement : OPC 43 Grade conforming to IS 8112
  3. Type of mineral admixture : fly ash conforming to IS 3812-(Part-1)
  4. Max. nominal size of aggregate : 20 mm
  5. Min. Cement content : 340 Kg/m³ (From table 5 of IS 456:2000 - Exposure condition)
  6. Max. w/c ratio : 0.45 (From table 5 of IS 456:2000 - Exposure condition)
  7. Workability : 100 mm (Slump value for pumpable concrete)
  8. Exposure Condition : Very Severe (For Reinforced Concrete)
  9. Method of concrete placing : Pumping
  10. Type of aggregate : Crushed angular aggregate
  11. Chemical admixture typr : Superplasticizer

• Test Data for Materials
  1. Cement used : OPC 43 grade conforming to IS 8112
  2. Specific gravity : 3.15
  3. fly ash : Conforming ot IS 3812-(Part-1)
  4. Specific gravity of fly ash : 2.2
  5. Chemical admixture : Superplasticizer conforming to IS 9103
  6. Specific Gravity of :
     • Coarse aggregate : 2.74
     • Fine aggregate : 2.74
  7. Water absorption :
     • Coarse aggregate : 0.5 %
     • Fine aggregate : 1.0 %
  8. Free srface Moisture :
     • Coarse aggregate : Nil
     • Fine aggregate : Nil
  9. Sieve analysis :
     • Coarse aggregate : Conforming to table 2 of IS 383
     • Fine aggregate : Conforming to grade zone I of table 4 of IS 383

• Target Strength for Mix Proportion

f'ck = fck + 1.65 x S

From table 1 of IS 10262:2009 Standerd daviation = 5 N/mm²

therefore, f'ck = 35 + (1.65 x 5)

f'ck = 43.25

• Selection of w/c ratio :

From table 5 of IS 456:2000 for Very Severe exposure condition maximum w/c ratio = 0.45

• Slection ofWater content :

From table 2 of IS 20262:2009, maximum water content for 20 mm aggregate = 186 litres (For 25 to 50 mm of slump)

So, estimated water content for 100 mm slump value = 186 + [(6/100) x 186)

= 197 litres.

as Superplasticizer is used so it will reduce the water content upto 30 %

Hence, arrived water content = 197 x (70/100)

= 137.9 litres or 138 litres

• Calculation of cement content :

w/c ratio = 0.45

Cementitious Material (Cement + fly ash) Content = 138 / 0.45 = 306.66 Kg/m³

since from table 5 of IS 456:2000 cement content for Very severe exposure condition is = 340 Kg/m³

So , Cementitious Material (Cement + fly ash) Content = 340 Kg/m³

Now, to proportion a mix containing fly ash the folowing steps are suggested :

1. The % of fly ash needs to be decided based on project requirement and quality of materials.
2. In some cases increase in cementitious material can be warrented. Increase in cementitious material content and it's % may be based on experiencce and trial. here we increase 10 % of cementitious material

therefore, Cementitioua material conent = 340 x 1.10 =374 Kg/m³

water content = 138 litres

so, w/c ratio will be now = 138 / 374 = 0.368

Flyash @ 30 % total Cementitious material content = 374 x 30% = 112.2 Kg/m³ or 112 Kg/m³

Cement (OPC) = 374 - 112.2 = 261.8 Kg/m³ or 262 Kg/m³

• Proportion of Volume of CA and FA content :

from table 3 of IS 10262:2009 volume of coarse aggregate corrospond to 20 mm size of aggregate & fine aggregate (Zone 1) for w/c ratio 0.50=0.60

in present case w/c ratio = 0.45

so,volume of coarse aggregate should be increased to decrase the fine aggregate content

Formula for Volume of coarse aggregate for w/c ratio of 0.45 = [((0.5 - w/c) / 0.05) x 0.01 + Vol. of aggregate as per Table 3 of IS 10262:2009]

corrected volume of coarse aggregate for w/c ratio of 0.45 = 0.61

for pumpable concrete these values are reduced by 10%

therefore , Voume of coarse aggregate = 0.61 x 0.9 = 0.549

& Volume of fine aggregate = 1 - 0.558 = 0.451

• Mix Calculation :
  1. Volume of concrete = 1 km³
  2. Volume of Cement = 0.083 m³
  3. Volume of fly ash = 0.0509 m³
  4. Volume of water = 0.138 m³
  5. Volume of Chemical admixture = 0.006 m³
  6. Volume of aggregate(FA & CA) = 0.7221 m³
  7. Mass of CA = 1086.2 kg/m³
  8. Mass of FA = 892.3 kg/m³

• Mix proportion for trial 1 :
  • Cement = 262 kg/m³
  • Fly ash = 112 kg/m³
  • Water = 138 kg/m³
  • FA = 892.3 kg/m³
  • CA = 1086.2 kg/m³
  • Chemical admixture = 7kg/m³
  • w/c ratio = 0.368 kg/m³

• trial mix ratio = 1 : 2.38 : 2.90

2. Concrete Mix Design for M50 grade concrete without fly ash :-

Solution :

• Stipulations for Proportioning
  1. Grade Designation : M50
  2. Type of Cement : OPC 43 Grade conforming to IS 8112
  3. Max. nominal size of aggregate : 20 mm
  4. Min. Cement content : 360 Kg/m³ (From table 5 of IS 456:2000 - Exposure condition)
  5. Max. w/c ratio : 0.40 (From table 5 of IS 456:2000 - Exposure condition)
  6. Workability : 100 mm (Slump value for pumpable concrete)
  7. Exposure Condition : Extreme (For Reinforced Concrete)
  8. Method of concrete placing : Pumping
  9. Type of aggregate : Crushed angular aggregate
  10. Chemical admixture typr : Superplasticizer

• Test Data for Materials
  1. Cement used : OPC 43 grade conforming to IS 8112
  2. Specific gravity : 3.15
  3. Chemical admixture : Superplasticizer conforming to IS 9103
  4. Specific Gravity of :
     • Coarse aggregate : 2.74
     • Fine aggregate : 2.74
  5. Water absorption :
     • Coarse aggregate : 0.5 %
     • Fine aggregate : 1.0 %
  6. Free srface Moisture :
     • Coarse aggregate : Nil
     • Fine aggregate : Nil
  7. Sieve analysis :
     • Coarse aggregate : Conforming to table 2 of IS 383
     • Fine aggregate : Conforming to grade zone I of table 4 of IS 383

• Target Strength for Mix Proportion

f'ck = fck + 1.65 x S

From table 1 of IS 10262:2009 Standerd daviation = 5 N/mm²

therefore, f'ck = 50 + (1.65 x 5)

f'ck = 58.25

• Selection of w/c ratio :

From table 5 of IS 456:2000 for Very Severe exposure condition maximum w/c ratio = 0.40

• Slection ofWater content :

From table 2 of IS 20262:2009, maximum water content for 20 mm aggregate = 186 litres (For 25 to 50 mm of slump)

So, estimated water content for 100 mm slump value = 186 + [(6/100) x 186)

= 197 litres.

as Superplasticizer is used so it will reduce the water content upto 30 %

Hence, arrived water content = 197 x (70/100)

= 137.9 litres or 138 litres

• Calculation of cement content :

w/c ratio = 0.4

Cementitious Material (Cement + fly ash) Content = 138 / 0.4 = 345 Kg/m³

since from table 5 of IS 456:2000 cement content for Extreme exposure condition is = 360 Kg/m³

here 345 kg/m³ < 360 kg/m³

So, Cement content = 360 kg/m³

• Calculation of Volume of CA and FA content :

from table 3 of IS 10262:2009 volume of coarse aggregate corrospond to 20 mm size of aggregate & fine aggregate (Zone 1) for w/c ratio 0.50=0.60

in present case w/c ratio = 0.4

so,volume of coarse aggregate should be increased to decrase the fine aggregate content

Formula for Volume of coarse aggregate for w/c ratio of 0.4 = [((0.5 - w/c) / 0.05) x 0.01 + Vol. of aggregate as per Table 3 of IS 10262:2009]

corrected volume of coarse aggregate for w/c ratio of 0.4 = 0.62

for pumpable concrete these values are reduced by 10%

therefore , Voume of coarse aggregate = 0.62 x 0.9 = 0.558

& Volume of fine aggregate = 1 - 0.558 = 0.442

• Mix Calculation :
  1. Volume of concrete = 1 km³
  2. Volume of Cement = 0.114 m³
  3. Volume of water = 0.138 m³
  4. Volume of Chemical admixture = 0.006 m³
  5. Volume of aggregate(FA & CA) = 0.742 m³
  6. Mass of CA = 1134.4 kg/m³
  7. Mass of FA = 898.6 kg/m³

• Mix proportion for trial 1 :
  • Cement = 360 kg/m³
  • Water = 138 kg/m³
  • FA = 898.6 kg/m³
  • CA = 1134.4 kg/m³
  • Chemical admixture = 7kg/m³
  • w/c ratio = 0.4 kg/m³

• trial mix ratio = 1 : 2.49 : 3.15