Project on Concrete Mix Design for various grades of Concrete
Mix design for M35 grade concrete with fly ash
Step-1
Proportioning
- Grade designation : M35
- Type of cement : opc 43 grade conforming to IS 8112
- Type of mineral admixture : fly ash confirming to IS 3812(part 1)
- Maximum nominal size of aggregates :20mm
- Minimum cement content : 320kg/m^3 ( Table :5 IS 456-2000,based on exposutr condition)
- Maximum w/c ratio : 0.45 ( Table :5 IS 456-2000,based on exposutr condition)
- Workability : 100mm slump value of pumpable concrete
- Exposure condition : severe
- Method of concrete placing : pumping
- Degree of supervision : Good
- Type of aggregate : crushing angular aggregate
- Maximum cement content : 450kg/m^3
- Chemical admixture type : Superplaticizer.
Step - 2
Test data for materials
- Cement used : OPC 43 grade confirming to IS 8112
- Specific gravity of cement : 3.15
- Fly asg : conforming to IS 3812 part 1
- Specific gravity of fly ash : 2.2
- Chemical admixture : superplaticizer conforming to IS 9103
- Specific gravity of : CA : 0.5%
FA : 1%
- Free surface moisture : CA : Nil
FA : Nil
Step -3
To find target mean strength for mix proportioning
Target mean strength f'ck = fck +1.65s
= 35 +1.65*5 =43.25 N/mm^2
fck- Characteristic compressive strength
s- Standard deviation
Step-4
Selection of water-cement ratio
Maximum water-cement ratio =0.45 (for severe condition ,from table 5 of IS 456-2000)
On experience water- cement ratio =0.4
0.4 <0.45, Hence OK.
Step -5
Calculation of water content
Maximum water content for 20mm aggregate =186 litres ( Table 2 of IS 1026:2009) for 25mm to 50mm slump range
For 100 mm slump ,= 186+(6/100)*186 =197 litres
As superplaticizer is used, the water content is reduced upto 30%
Based on trials water content reduction of 29% is achieved with plasticizer
Hence arrived water content = 197*0.71 = 140 litres
Step - 6
Calculation of cement content
Water-cement ratio = 0.4
Cement + flyash=140/0.4=350kg/m^3
In table 5 of IS 456-2000,the cement for severe exposure=320kg/m^3
350kg/m^3 > 320kg/m^3
Cementatious material content = 350*1.1=385kg/m^3
Water content = 140kg/m^3
so,w/c ratio =140/385=0.364
Fly ash at 30% total cementatious material content = 35-30%=115kg/m^3
Cement =385-115=270kg/m^3
Saving of cement while using fly ash = 350-270=80kg/m^3
Flyash beign utilized = 115kg/m^3
Step - 7
Volume of aggregate
Volume of coarse aggregate = 0.64*0.9=0.576
volume of fine aggregate = 1-0.576=0.424
Step - 8
mix calculation
- Volume of concrete = 1m^3
- Volume of cement = (Mass of cement/Specific gravity of cement)*1/1000
= (270/3.15)*1/1000=0.086m^3
- Volume of fly ash = (mass of flyash/specific gravity of flyash)*1/1000
= (115/2.2)*1/1000=0.052m^3
- Volume of water = (mass of water/specific gravity of water)*1/1000
= (140/1)*1/1000=0.140m^3
- Volume of chemical admixture=(Mass of admixture/specific gravity of admixture)*1/1000
=(7.6/1.14)*1/1000=0.006m^3
- Volume of aggregate=Volume of concrete-(volume of cement+volume of flyash+volume of water+volume of chemical admixture)=1-(0.086+0.052+0.140+0.006)=0.716m^3
- Mass of coarse aggregate= f*Volume of coarse aggregate*specific gravity of coarse aggregate*1000
= 0.716*0.576*2.74*1000=1130kg/m^3
- Mass of fine aggregate= f*volume of fine aggregate*specific gravity of fine aggregate*1000
=0.716*0.424*2.74*1000=831kg/m^3
Step - 9
Mix proportion
Cement = 270kg/m^3
Fly ash = 115kg/m^3
Water = 140kg/m^3
Fine aggregate = 831kg/m^3
Coarse aggregate = 1130kg/m^3
Chemical admixture = 7kg/m^3
Water cement ratio = 0.364
Mix ratio 1:2.15:2.94
Mix design of M50 grade concrete
Step - 1
Proportioning
- Grade designation : M50
- Type of cement : OPC grade 43 conforming to IS 8112
- Maximum nominal sizeof aggregate: 20mm
- Minimum cement content : 320kg/m^3
- Maximum water-cement ratio : 0.45 (Table :5 IS 456-2000,based on exposure condition)
- Workability :100mm ,slump value of pumpable concrete
- Exposure condition : Severe ( for reinforced concrete)
- Method of concrete placing : Pumping
- Degree of supervision : Good
- Type of aggregate: Crushed angular aggregate
- Maximum cement content : 450 kg/m^3.
- Chemical admixture type : Superplaticizer.
Step-2
Test data for materials
- Cement used : OPC 43 grade confirming to IS 8112
- Specific gravity of cement : 3.15
- Chemical admixture : Superplaticizer conforming to IS 9103
- Specific gravity of :
Coarse aggregate : 2.74
Fine aggregate : 2.74
- Water absorption :
Coarse aggregate : 0.5%
Fine aggregate : 1%
- Free surface moisture
Coarse aggregate : Nil
Fine aggregate : Nil
Step-3
To find target mean strength for proportioning
Target mean strength , f'ck =fck +1.65 s
= 50+1.65*5 =58.25N/mm^2
fck = Characteristic strength
s=standard deviation
Step-4
Selection of water cement ratio
From Table :5 of IS 456-2000, by exposure condition
Here severe condition is considered , Maximum water-cement ratio=0.45
Based on experience water- cement ratio =0.4
0.4 <0.45
Step -5
Selection of water content
Maximum water content for 20mm aggregate =186 litres ( Table 2 of IS 1026:2009) for 25mm to 50mm slump range
For 100 mm slump ,= 186+(6/100)*186 =197 litres
As superplaticizer is used, the water content is reduced upto 30%
Based on trials water content reduction of 29% is achieved with plasticizer
Hence arrived water content = 197*0.71 = 140 litres
Step -6
Calculation of cement content
Water - cement ratio = 0.4
Cement content = 140/0.4 =350kg/m^3
In table 5 of IS 456-2000, the cement content for severe exposure =320kg/m^3
350kg/m^3 > 320kg/m^3
Step -7
Volume of aggregate
Volume of coarse aggregate = 0.64*0.9 = 0.576
Volume of fine aggregate = 1-0.576 =0.424
Step-8
Mix calculation
Volume of concrete = 1m^3
Volume of cement = (mass of cement/specific gravity of cement)*1/1000
= (350/3.15)*1/1000=0.111m^3
Volume of water = (mass of water/specific gravity of water)*1/1000
=(140/1)*1/1000=0.140m^3
Volume of chemical admixture=(mass of admixture/specific gravity of admixture)*1/1000
=(7.6/1.145)*1/1000=0.006m^3
Volume of aggregate=volume concrete-(volume of cement+volume of water+volume of chemical admixture)
=1-(0.111+0.140+0.006)=0.743m^3
Mass of coarse aggregate=e*volume of coarse aggregate*specific gravity of coarse aggregate*1000
=0.743*0.424*2.74*1000=1173kg/m^3
Mass of fine aggregate=e*volume of fine aggregate*specific gravity of fine aggregate*1000
=0.743*0.424*2.74*1000=863kg/m^3
Step-9
Mix proportion
Cement = 350kg/m^3
Water = 140kg/m^3
Fine aggregate = 863kg/m^3
Coarse aggregate = 1173kg/m^3
Chemical admixture = 7kg/m^3
W/C ratio = 0.4
Mix ratio 1:2.46:3.35