Project on Concrete Mix Design for various grades of Concrete
AIM
To calculate the concrete mix design for M35 Grade concrete with fly ash
INTRODUCTION
Concrete mix design is a systmatic process of choosing economical relative proportation of various ingrediants from available mterial that gives the concrete of desired workability. The process of selecting suitable ingrediants of concrete of required strebgth, ductality, workability as economical as possible is known as concrete mix design. It depends on quality and quantity of cement, water and aggregates.
STEPS:
1. Target mean strength of concrete = 35 + (1.65 * 5 ) = 43.25N/mm^2
2. Selection of water cement ratio
From table 5 os IS 456 : 2000 for severe exposure Maximum water cement ratio = 0.4
Based on experience adopt water cement ratio as 0.40
0.40<0.45, hence O.K
3. Selection of water content
From table 2 of IS 10262 :2009 , maximum water cement ratio of 20 mm aggregate = 186 litre
Estimated water content = 186+6%*186 = 197 litre
As super plasticizer is used, the water content can be reduced upto 30%
Based on trails of water content on reduction of 25% is achieved with plasticizer
Hence arriced water content = 197*0.75 = 148 litres
4. Calculaton of cement content
water cement ratio = 0.4
cementitious material = 148/0.4 = 370 kg/m^3
370>320 , Hence O.K
Now to proportion mix containing fly ash the following steps are adopted
a. The percentage of fly ash needs to be decided based on the project requirement and quality of materials
b. In some cases increase in the cementitious material can be warrented.Increase in 10% of material is adopted
Cementitious material content = 370*1.10 = 407 kg/m^3
Water content = 140kg/m^3
water cement ratio = 140/407 = 0.34
Fly ash at 30% total cementitious material = 407*30% = 122kg/m^3
Cement (opc) = 407-122 = 285kg/m^3
Saving cement using fly ash = 407-285 = 122kg/m^3
Fly ash being utilized = 122kg/m^3
5. Proportion of coarse and fine aggregate
From table 3 of IS 10262 : 2009 volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate zone 1 for water cement ratio of 0.5 = 0.6
At present water cement ratio is = 0.40
The corrected volume of coarse aggregate for water cement ratio = 0.40 = 0.62
For pumpable concrete reduced by 10%
Volume of coarse aggregate = 0.62*0.9 = 0.56
Volume of fine aggregate = 1-0.56 = 0.44
6. Mix calculations
a. Volume of concrete = 1m^3
b. Volume of cement = 285/3.15*1000 = 0.090 m^3
c. Volume of Fly ash = 122/2.2*1000 = 0.055 m^3
d. volume if water = 148/1000 = 0.148 m^3
e. Volume of chemical admixture = 7/1.145*1000 = 0.006 m^3
f. Volume of aggregate = a-(b+c+d+e) = 0.701 m^3
g. Mass of coarse aggregate = 0.701*0.56*2.74*1000 = 1075.61kg/m^3
h. Mass of fine aggregate = 0.701*0.44*2.74*1000 = 845.12kg/m^3
7. Mix proportions
Cement = 285 kg/m^3
Fly ash = 122 kg/m^3
Water = 148 kg/m^3
Fine aggregate = 845.12 kg/m^3
Coarse aggregate= 1075.61 kg/m^3
Chemical admixtures = 7 kg/m^3
water cement ratio = 0.34
Trial mix ratio = 1 : 2.96 : 3.77
8. The slump must be measured and the water content, dosage of admixture shall be adjusted for achieving the required slump on trial. The mix proporation shall be reworked for the actual water content and checked for durability requirements.
9. Two more trials having variation of 10% of water cement ratio shall be carried out and a graph between water cement ratio and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials. However durability shall be met.
RESULT:
Concrete mix design of given M35 concrete grade is 1 : 2.96 : 3.77
AIM :
To calculate the concrete mix design for M50 Grade concrete without fly ash
INTRODUCTION
Concrete mix design is a systmatic process of choosing economical relative proportation of various ingrediants from available mterial that gives the concrete of desired workability. The process of selecting suitable ingrediants of concrete of required strebgth, ductality, workability as economical as possible is known as concrete mix design. It depends on quality and quantity of cement, water and aggregates.
STEPS:
1. Target mean strength of concrete = 50 + (1.65 * 5 ) = 58.25 N/mm^2
2. Selection of water cement ratio
From table 5 os IS 456 : 2000 for severe exposure Maximum water cement ratio = 0.4
Based on experience adopt water cement ratio as 0.40
0.40<0.45, hence O.K
3. Selection of water content
From table 2 of IS 10262 :2009 , maximum water cement ratio of 20 mm aggregate = 186 litre
Estimated water content = 186+6%*186 = 197 litre
As super plasticizer is used, the water content can be reduced upto 30%
Based on trails of water content on reduction of 25% is achieved with plasticizer
Hence arriced water content = 197*0.75 = 148 litres
4. Calculaton of cement content
water cement ratio = 0.4
cement content = 148/0.4 = 370 kg/m^3
370>320 , Hence O.K
5. Proportion of coarse and fine aggregate
From table 3 of IS 10262 : 2009 volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate zone 1 for water cement ratio of 0.5 = 0.6
At present water cement ratio is = 0.40
The corrected volume of coarse aggregate for water cement ratio = 0.40 = 0.62
For pumpable concrete reduced by 10%
Volume of coarse aggregate = 0.62*0.9 = 0.56
Volume of fine aggregate = 1-0.56 = 0.44
6. Mix calculations
a. Volume of concrete = 1m^3
b. Volume of cement = 370/3.15*1000 = 0.117 m^3
c. volume if water = 148/1000 = 0.148 m^3
d. Volume of chemical admixture = 7/1.145*1000 = 0.006 m^3
e. Volume of aggregate = a-(b+c+d) = 0.729 m^3
f. Mass of coarse aggregate = 0.729*0.56*2.74*1000 = 111.8.5kg/m^3
g. Mass of fine aggregate = 0.729*0.44*2.74*1000 = 878.8kg/m^3
7. Mix proportions
Cement = 370 kg/m^3
Water = 148 kg/m^3
Fine aggregate = 878.8 kg/m^3
Coarse aggregate= 1118 5 kg/m^3
Chemical admixtures = 7 kg/m^3
water cement ratio = 0.4
Trial mix ratio = 1 : 2.37 : 3.02
8. The slump must be measured and the water content, dosage of admixture shall be adjusted for achieving the required slump on trial. The mix proporation shall be reworked for the actual water content and checked for durability requirements.
9. Two more trials having variation of 10% of water cement ratio shall be carried out and a graph between water cement ratio and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for field trials. However durability shall be met.
RESULT:
Concrete mix design of given M50 concrete grade is 1 : 2.37 : 3.02