Project on Concrete Mix Design for various grades of Concrete
Aim-Calculate the concrete mix design for M50 grade concrete without fly ash.
Introduction-In this we will see the whole procedure of calculating mix design for M50 grade. Final result will show us the exact proportion of cement sand and aggregate.
-Now we are considering some data for calculation:-
1]Stipulations for concrete mix design:
Grade designation=M50
Type of cement=OPC 53 (IS 12269)
Maximum nominal size of aggregate=20mm
Minimum cement content=360 kg/m3 (IS 456 2000)
Maximum w/c ratio=0.45 (table 5 IS 456 2000)
Workability=100mm slump
Exposuer condition=Extreme
Type of agg=Crushed angular aggregates
Maximum cement content=450 kg/m3
Method of concrete placing=Pumping
Chemical admixture type= Super plasticizer
2]Test data for materials:
Cement used=OPC 53
Sp. gravity of cement=3.15
Chemical admixtures = Super plastisizers
Sp. gravity of- Coarse agg 20mm=2.74
Fine agg=2.74
Water absorption-Coarse agg=0.5%
Fine agg=2.5%
Free surface moisture-Coarse agg=Nill
Fine agg=Nill
Sieve analysis:Coarse agg-table 2 IS 383
Fine agg-table4 grading zoneII of IS 383
Procedure:
1]Target strength for mix proportioning,f'ck=fck+1.65*S
=50+1.65*5
=58.25N/mm2
2]Selection of w/c ratio=0.35 from table 5 IS456-2000
3]Selection of water content:From table 2 IS 10262-2009
water content for 20mm agg=186lit(for 25-50mm slump
For 100mm slump=186+6/100 *186=197 litre
If plasticizer used then water content reduced by 20% and above.
So, arrived water content=197-[197*(20/100)]=158 lit
4]Calculation of cement content:Adopted w/c ratio=0.35
Cement content=158/0.35=451 kg/m3
As per table 5 IS 456-2000 minimum cement content for extreme exposure condition=360 kg/m3
S0, 451>360 hence ok
5]Proportion of volume of coarse aggregate and fine aggregate:
from table 3 IS10262-2009, volume of coarse aggregate corresponding to 20mm size and fine aggregate for w/c ratio 0.5=0.62
Here,w/c ratio=0.35, so volume of coarse aggregate need to be increase or decrease
As w/c ratio is decrease by 0.10, proportion of coarse agg increase by 0.02
Now, volume of coarse agg for w/c ratio 0.35=0.65
For pumpable concrete these value reduced by 10%
Volume of coarse agg=0.65*0.9=0.585
Volume of fine agg=1-0.585=0.415
6]Mix calculations:
a)Volume of concrete=1m3
b)Volume of cement=mass of cement/sp. gravity of cement*1/1000
=451/3.15*1/1000
=0.143m3
c)Volume of water=mass of water/sp. gravity of water*1/1000
=158/1*1/1000
=0.158m3
d)Volume of chemical admixtures=1.75lit/m3 (By trial & error method used 0.4% by wt of cement)
e)Volume of all in aggregate=[a-(b+c+d)]
=[1-(0.143+0.158+0.004)]
=0.695m3
f)Mass of coarse aggregate=e*volume of coarse agg*sp.gravity coarse agg
=0.695*0.585*2.74*1000
=1114.01kg/m3
g)Mass of fine aggregate=e*volume of fine agg*sp.gravity fine agg
=0.695*0.415*2.74*1000
=790.28 kg/m3
Mix proportions:
Cement=451 kg/m3
Water=158 l/m3
Fine agg=791 kg/m3
Coarse agg=1114 kg/m3
Chemical admixture=1.34 kg/m3
W/C ratio=0.35
Mix proportion by weigth=1:1.75:2.47
Result:
Mix proportion obtain for M50 grade is 1:1.75:2.47
Aim-Calculate the concrete mix design for M35 grade concrete with fly ash.
Introduction-In this we will see the whole procedure of calculating mix design for M35 grade. Final result will show us the exact proportion of cement, fly ash, sand and aggregate.
-Now we are considering some data for calculation:-
1]Stipulations for concrete mix design:
Grade designation=M35
Type of cement=OPC 53 (IS 12269)
Type of admixture=fly ash
Maximum nominal size of aggregate=20mm
Minimum cement content=340 kg/m3 (IS 456 2000)
Maximum w/c ratio=0.45 (table 5 IS 456 2000)
Partial replacement of cement by fly ash=30%
Workability=100mm slump
Exposuer condition=Very severe
Type of agg=Crushed angular aggregates
Maximum cement content=450 kg/m3
Method of concrete placing=Pumping
Chemical admixture type= Super plasticizer
2]Test data for materials:
Cement used=OPC 53
Sp. gravity of cement=3.15
Chemical admixtures = Super plastisizers
Sp. gravity of- Coarse agg 20mm=2.74
Fine agg=2.74
Water absorption-Coarse agg=0.5%
Fine agg=2.5%
Free surface moisture-Coarse agg=Nill
Fine agg=Nill
Sieve analysis:Coarse agg-table 2 IS 383
Fine agg-table4 grading zoneII of IS 383
Procedure:
1]Target strength for mix proportioning,f'ck=fck+1.65*S
=35+1.65*5
=43.25N/mm2
2]Selection of w/c ratio=0.45 from table 5 IS456-2000
3]Selection of water content:From table 2 IS 10262-2009
water content for 20mm agg=186lit(for 25-50mm slump
For 100mm slump=186+6/100 *186=198 litre
If plasticizer used then water content reduced by 20% and above.
So, arrived water content=198-[198*(20/100)]=160 lit
4]Calculation of cement content:Adopted w/c ratio=0.45
Cement content=160/0.45=356 kg/m3
Since fly ash is used, here we have increased 10% of cementatious content
Final cementatious content=356*1.10=391.6 kg
As per table 5 IS 456-2000 minimum cement content for very severe exposure condition=340 kg/m3
S0, 391.6>340 hence ok
Fly ash content requirement is 30%
Total cementatious material=391.6*0.30=117.48~118 kg
Cement content requirement=391.6-117.48=274.12
Calculation of super plasticiers @ 0.6% of cementatious content=391.6*(0.6/100)=2.35 kg
5]Proportion of volume of coarse aggregate and fine aggregate:
from table 3 IS10262-2009, volume of coarse aggregate corresponding to 20mm size and fine aggregate for w/c ratio 0.5=0.62
Here,w/c ratio=0.45, so volume of coarse aggregate need to be increase or decrease
As w/c ratio is decrease by 0.50, proportion of coarse agg increase by 0.01
Now, volume of coarse agg for w/c ratio 0.45=0.63
For pumpable concrete these value reduced by 10%
Volume of coarse agg=0.63*0.9=0.567
Volume of fine agg=1-0.567=0.433
6]Mix calculations:
a)Volume of concrete=1m3
b)Volume of cement=mass of cement/sp. gravity of cement*1/1000
=275/3.15*1/1000
=0.087m3
c)Volume of fly ash=mass of fly ash/sp. gravity of fly ash*1/1000
=118/2.5*1/1000
=0.041m3
d)Volume of water=mass of water/sp. gravity of water*1/1000
=160/1*1/1000
=0.160m3
e)Volume of chemical admixtures=2.35/(1.12*1000)
=0.002m3
f)Volume of all in aggregate=[a-(b+c+d+e)]
=[1-(0.087+0.041+0.160+0.002)]
=0.71m3
g)Mass of coarse aggregate=e*volume of coarse agg*sp.gravity coarse agg
=0.71*0.567*2.74*1000
=1103.04kg/m3
g)Mass of fine aggregate=e*volume of fine agg*sp.gravity fine agg
=0.71*0.433*2.74*1000
=842.36 kg/m3
Mix proportions:
Cement=275 kg/m3
Fly ash=118 kg
Water=160 l/m3
Fine agg=843 kg/m3
Coarse agg=1103 kg/m3
Chemical admixture=2 kg/m3
W/C ratio=0.45
Mix proportion by weigth=1:0.4:3.07:4.01
Result:
Mix proportion obtain for M35 grade with fly ash is 1:0.4:3.07:4.01
This represent proportion of cement, fly ash, fine agg, coarse agg.