Project on Concrete Mix Design for various grades of Concrete

1) Concrete mix design fro grade M35 using fly ash

• Target mean stength of concrete(f'ck)=fck+1.65S

considering S value as 5 N/mm2 from IS code 10262:2009 table 1

:. f'ck=35+1.65x5= 43.25M/mm2

• Selection of water cement ratio from IS code 456:2000 table 5 is 0.40
• Selection of water content

For 20mm aggregate the water required is 186 ltr

therefore, for 10mm slump 6% water content is increased so total water conent is 197ltr.

using Plasticizer the water gets reduce by 29%. so 197x0.71=140ltr

• Selection of cement content

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

from IS code 456:2000 table 5 is 340kg/m3< 350kg/m3 hence ok

considering 30% of fly ash in the mix and increasing the mix by 10% ie. total cementitious content will be 350x1.1=385kg/m3.

:.flyash = 385x0.3=115.5kg/m3

Cement=385-115.5=269.5kg/m3

• volume of coarse aggregate and Fine aggregates from IS10262:2009 Table 3.

Volume of coarse aggregate corresponding to 20mm size aggregate and fineaggregate(Zone I) for water cement ratio 0.5=0.6.

In our case the w/c ratio is 0.4 hence increasing the qty of coarse aggregate and decrease the qty of fine aggregates. As the W/C ratio is lowered by 0.1 the proportion of volume of coarse aggregate is increased by 0.02. Therefore the corrected volume of C.A for W/C is 0.62 and F.A is 1-0.62=0.48

• Mix calculations
  • volume of concrete=1m3
  • volume of cement=mass of cement/S.G of cement x 1/1000=269.5/3.15x1/1000=0.0855m3
  • Volume of fly ash= mass of Fly ash/S.G of fly ash x 1/1000=115.6/2.2x1/1000=0.0525m3
  • Volume of water= mass of water/S.G of water x 1/1000=140/1x1/1000=0.140m3
  • volume of chemical admixture= mass of chemical Admix/S.G of chmical Admix x 1/1000=7.6/1.145x1/1000=0.006m3
  • volume of aggregate= (1-(0.0855+0.0525+0.14+0.006)=0.716m3
  • mass of C.A= Volume of Aggregatesx volume of C.Ax S.G of C.A x1000=0.716x0.62x2.7x1000=1198.58kg/m3
  • mass of F.A= Volume of Aggregatesx volume of F.Ax S.G of F.A x1000=0.716x0.48x2.7x1000=927.936kg/m3
• Mix proportions:
  • Cement-269.5kg/m3
  • Flyash-115.5kg/m3
  • Water-140kg/m3
  • Fine aggregate-927.936kg/m3
  • Coarse aggregate-1198.58kg/m3
  • Chemical admixture- 7kg/m3
  • W/C ratio-0.4
  • Trial Mix Ratio-1:2.41:3.11

2) Concrete mix design fro grade M50 without fly ash

• Target mean stength of concrete(f'ck)=fck+1.65S

considering S value as 5 N/mm2 from IS code 10262:2009 table 1

:. f'ck=50+1.65x5= 58.25M/mm2

• Selection of water cement ratio from IS code 456:2000 table 5 is 0.35
• Selection of water content

For 20mm aggregate the water required is 186 ltr

therefore, for 10mm slump 6% water content is increased so total water conent is 197ltr.

using Plasticizer the water gets reduce by 29%. so 197x0.71=140ltr

• Selection of cement content

cementitious content (Cement)=140/0.4=350kg/m3

from IS code 456:2000 table 5 is 340kg/m3< 350kg/m3 hence ok

increasing the mix by 10% ie. total cementitious content will be 350x1.1=385kg/m3.

Cement=385kg/m3

• volume of coarse aggregate and Fine aggregates from IS10262:2009 Table 3.

Volume of coarse aggregate corresponding to 20mm size aggregate and fineaggregate(Zone I) for water cement ratio 0.5=0.6.

In our case the w/c ratio is 0.4 hence increasing the qty of coarse aggregate and decrease the qty of fine aggregates. As the W/C ratio is lowered by 0.1 the proportion of volume of coarse aggregate is increased by 0.01. Therefore the corrected volume of C.A for W/C is 0.61 and F.A is 1-0.61=0.49

• Mix calculations
  • volume of concrete=1m3
  • volume of cement=mass of cement/S.G of cement x 1/1000=385/3.15x1/1000=0.122m3
  • Volume of water= mass of water/S.G of water x 1/1000=140/1x1/1000=0.140m3
  • volume of chemical admixture= mass of chemical Admix/S.G of chmical Admix x 1/1000=7.6/1.145x1/1000=0.006m3
  • volume of aggregate= (1-(0.122+0.14+0.006)=0.732m3
  • mass of C.A= Volume of Aggregatesx volume of C.Ax S.G of C.A x1000=0.732x0.61x2.74x1000=1223kg/m3
  • mass of F.A= Volume of Aggregatesx volume of F.Ax S.G of F.A x1000=0.732x0.49x2.74x1000=983kg/m3
• Mix proportions:
  • Cement-385kg/m3
  • Water-140kg/m3
  • Fine aggregate-983kg/m3
  • Coarse aggregate-1223kg/m3
  • Chemical admixture- 7kg/m3
  • W/C ratio-0.4
  • Trial Mix Ratio-1:2.55:3.17