Project on Concrete Mix Design for various grades of Concrete

1.Aim and introduction:

     To calculate a mix design for M35 grade concrete with fly ash.

Procedure: 

 Grade designation:M35

Type of cement:OPC53

Maximum nominal size of aggregate:20mm

Exposure type:Severe Exposure

Minimum cement content:340kg

Workability:100mm slump

Method of concrete placing:Pumping

Types of aggregate:Crushed angular

Maximum cement content:450kg

Chemical admixture:Superplasticizer

Specific gravity of cement:3.15

Specific gravity of fine aggregate:2.74

Specific gravity of coarse aggregate:2.74

Coarse and Fine aggregate :grade 1

Mineral admixture:Fly ash

Specific gravity of flyash:2.2

Target strength:

f'ck=fck+1.65S

s=standard deviation (S=5, from table 1 of IS10262:2009)

 =35+1.65*5

f'ck=43.25N/mm^2

Selection of water cement ratio:

From table 5 IS456:2000 exposed for severe condition ,maximum water-cement ratio is 0.45

Selection of water content:

From table 2 of IS456:2000

Maximum water content for 20mm aggregate is=186L

for 25-50mm above slump for every 25mm 3% is increased

Water content=186+(6/100*186)=197.16L

Superplasticizer is used water content can be reduced 20%

    =197.16-(29/100*197.16)=139.98~140L

Calculation of cement content:

Water cement ratio 0.40

Cementitious material(cement+fly ash)content=140/0.40=350kg

   350kg>340kg Hence ok.

Fly ash is used therefore cementitious material is increased by 10%

Cementitious material content =350*1.1=385kg/m^3

Water content 140L

Water-cement ratio=140/385=0.36

 Fly ash @30% total cementitious material content=385*30%=115.5kg/m^3~115kg/m^3

Cement content=385-115=270kg/m^3

Saving cement by using fly ash=350-270=80kg/m^3

Fly ash utilized=115kg/m^3

Volume of coarse aggregate and fine aggregate :

From table 3 of IS10262 20mm size aggregateand fine aggregate for water-cement ratio is 0.4=0.62

we have water-cement ratio0.4

volume of coarse aggregate increases by decresing fine aggregate 

As water-cement ratio is lower by 0.10,the proportion of the volume of coarse aggregate is increased by0.02

the corrected proportion of volume of Coarse aggregate the water-cement ratio of 0.4=0.62

For pumpable concrete it can be reduced by 10%

volume of coarse aggregate =0.62*0.9=0.56

volume of fine aggregate=1-0.56=0.44

Mix calculations:

volume of concrete=1m^3

volume of cement=270/3.15*1/1000=0.086m^3

volume of fly ash=115/2.2*1/1000=0.052m^3

volume of water=140/1*1/1000=0.140m^3

volume of chemical admixture=7.6/1.145*1/1000=0.006m^3

volume of aggregate=[a-(b+c+d+e)]=[1-(0.086+0.052+0.140+0.006)]=1-0.284=0.716m^3

Mass of coarse aggregate=f*volume of CA*Specific gravity of CA*1000=0.716*0.56*2.74*1000=1098.63kg/m^3

Mass of fine aggregate=f*volume of FA*Specific gravity of FA*1000=0.716*0.44*2.74*1000=863.20kg/m^3

Mix proportioning:

Cement=270kg/m^3

Fly ash=115kg/m^3

Water=140kg/m^3

Fine aggregate=863kg/m^3

Coarse aggregate=1098kg/m^3

Chemical admixture=7.16kg/m^3

water-cement ratio=0.40

Trial mix ratio=1:2.24:2.85.

2.Aim and introduction:

     To calculate a mix design for M50 grade concrete without fly ash.

Procedure: 

Grade designation:M50

Type of cement:OPC53

Maximum nominal size of aggregate:20mm

Exposure type:Extreme

Minimum cement content:360kg

Workability:100mm slump

Method of concrete placing:Pumping

Types of aggregate:Crushed angular

Maximum cement content:450kg

Chemical admixture:Superplasticizer

Specific gravity of cement:3.12

Specific gravity of fine aggregate:2.74

Specific gravity of coarse aggregate:2.56

Target strength:

f'ck=fck+1.65S

s=standard deviation (S=5, from table 1 of IS10262:2009)

=50+1.65*5=58.25N/mm^2

Selection of water cement ratio:

From table 5 IS456:2000 exposed for extreme condition ,maximum water-cement ratio is 0.35

Selection of water content:

From table 2 of IS456:2000

Maximum water content for 20mm aggregate is=186L

for 25-50mm above slump for every 25mm 3% is increased

Water content=186+(6/100*186)=197.16L

Superplasticizer is used water content can be reduced 20%

    =197.16-(29/100*197.16)=139.98~140L

Calculation of cement content:

Water-cement ratio=0.35

Cement content=140/0.35=400kg/m^3

For extreme exposure 360kg/m^3

     400kg>360kg   hence ok

Volume of coarse aggregate and fine aggregate :

From table 3 of IS10262 20mm size aggregateand fine aggregate for water-cement ratio is 0.5=0.62

we have water-cement ratio0.35

volume of coarse aggregate increases by decresing fine aggregate 

As water-cement ratio is lower by 0.10,the proportion of the volume of coarse aggregate is increased by0.02

the corrected proportion of volume of Coarse aggregate the water-cement ratio of 0.35=0.65

For pumpable concrete it can be reduced by 10%

volume of coarse aggregate =0.65*0.9=0.585

volume of fine aggregate=1-0.585=0.415

Mix calculations:

volume of concrete=1m^3

volume of cement=400/3.12*1/1000=0.128m^3

volume of water=140/1*1/1000=0.140m^3

volume of chemical admixture=8.2/1.145*1/1000=0.007m^3

volume of aggregate=[a-(b+c+d)]=[1-(0.128+0.140+0.007)]=1-0.284=0.725m^3

Mass of coarse aggregate=e*volume of CA*Specific gravity of CA*1000=0.725*0.585*2.74*1000=1162.10kg/m^3

Mass of fine aggregate=e*volume of FA*Specific gravity of FA*1000=0.725*0.4165*2.56*1000=770.24kg/m^3

Mix proportioning:

Cement=400kg/m^3

Water=140kg/m^3

Fine aggregate=770.24kg/m^3

Coarse aggregate=1162.10kg/m^3

Chemical admixture=7kg/m^3

water-cement ratio=0.35

Trial mix ratio=1:1.925:2.9.