Project on Concrete Mix Design for various grades of Concrete
Calculate the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash
Aim : To calculate the concrete mix design for M35 grade concrete with fly ash and M50 grade concrete without fly ash. Concrete is made of many ingredients which include cement, admixtures, aggregates etc. To attain desirable strength after curing and maintain workability of fresh concrete for required conditions like pumping, it is necessary to follow a specified standard procedure from code IS10262:2019.
Introducton :
1. Concrete mix design for M35 grade concrete with fly ash, super plasticizer and pumpable concrete for moderate exposure condition with dry aggregate and 75mm slump.
2. Concrete mix design for M50 grade concrete with out fly ash, super plasticizer and pumpable concrete for severe exposure condition with dry aggregate and 100mm slump.
Procedure :
Concrete mix design for M35 grade concrete with fly ash.
Step 1 : Stipulations for proportioning
Grade designation : M35
Type of cement : OPC 43 grade confirming to IS8112
Maximum nominal size of aggregate : 2omm
Minimum cement content : 340 Kg/m3 (For M35 grade concrete from Table 5 of IS456:2000)
Maximum water cement ratio : 0.5 (For moderate exposure from Table 5 of IS456:2000)
Workability : 75mm slump
Exposure condition : Moderate (For reinforced concrete)
Method of concrete placing : pumpable concrete
Degree of supervision : Good
Type of aggregate : Crushed angular aggregate
Chemical admixture type : Super plasticizer (confirming to IS8112)
Specific gravity of cement (From manufacturer) : 3.15
Specific gravity of coarse aggregate : 2.74
Specific gravity of fine aggregate : 2.74
Water absorption for coarse aggregate : 0.5%
Water absorption for fine aggregate : 0.5%
Free surface moisture for coarse aggregate : Nil
Free surface moisture for fine aggregate : Nil
Sieve analysis for coarse aggregate : Table 2 of IS383
Sieve analysis for fine aggregate : Table 4 of IS383 (Zone 1 grading)
Step 2 : Calculation of target mean strength for mix proportioning (Ft)
Ft = Fck + 1.65S (From IS456:2000)
Where "Ft" is target mean strength of concrete to be designed
"Fck" is compressive strength of concrete grade
"S" is standard deviation
Ft = 35N/mm2(for M35 grade concrete) + (1.65*5)[For M35 grade concrete standard deviation is v 5 from Table 2 of IS10262:2019]
Ft = 43.25N/mm2
Step 3 : Selection of water cement ratio
From graph of IS10262:2019, W/C ratio for target mean strength of 43.25N/mm2 and for OPC43 grade of cement (curve 2 of graph)
W/C = 0.37
From table 5 of IS456:2000, W/C ratio for moderate exposure condition is 0.5
W/C = 0.5
Minimum of both values is considered as actual water cement ratio, Which is
W/C = 0.37
Step 4 : Selection of water content
From Table 4 of IS10262:2019, for 20mm maximum nominal size of aggregate,
Maximum water content = 186L (for 25mm to 50mm slump)
Estimated water content for 75mm slump is (According to the same code approximate of 3% increase in water content is required for increase of 25mm slump)
= 186 + [(3/100)*186]
Estimated water content for 75mm slump is = 192L
As super plasticizer is used, water content is decreased by 30%
Hence, the final water content for 75mm slump with 20mm maximum nominal size of aggregate and with super plasticizer is = [192*(100-30)]/100]
= 134.4L
Water content = 134.4L
Step 5 : Calculation of cement content
W/C ratio = 0.37
134.4/C =0.37
C = 134.4/0.37
Cement content = 363.24 Kg/m3
(From IS456:2000, Table 5 Minimum cement content for M35 grade is 340Kg/m3 and for moderate exposure condition, it is 360Kg/m3)
363.24>340Kg/m3 and >360Kg/m3
Assuming, 10% of increse in cementitious materail (This percentage depends on the type of construction and properties of fly ash)
Cementitious content = cement + fly ash
Cementitious content = 1.1 times of cement content (as per our assumption)
= 1.1*363.24
= 400Kg/m3
Altered water cement ratio = 134.4/400
W/C = 0.34
30% of cement can be replaced by fly ash,
= 400*(30/100)
= 120Kg/m3
Hence, Fly ash content = 120Kg/m3
Revised cement content = 400-120 = 280Kg/m3
Cement content after adding 30% of fly ash = 280Kg/m3
Reduction in cement content, due to replament of 30% of cementitious material with fly ash = 363.24-280 = 83.24Kg/m3
Step 6 : Proportion of volume of coarse aggregate and fine aggregate content
From Table 5 of IS10262:2019,volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone1) for W/C ratio of 0.5 = 0.6
In ths case W/C ratio is 0.34, hence the volume of coarse aggregate is (for decrease of every 0.1 in W/C ratio, the proportion of volume of coarse aggregate is increased by 0.01)
= [(0.5-W/C)*0.01]/0.05+volume of coarse aggregare from table
= [(0.5-0.34)*0.01]/0.05+0.6
= 0.632
Corrected volume of coarse aggregate is = 0.632
For pumpable concrete, volume of coarse aggregate (is reduced by 10%) = 0.632*[(100-10)/100]
Volume of coarse aggregate= 0.57
Volume of fine aggreagte = 1- volume of coarse aggregate = 1-0.57
Volume of fine aggregate = 0.43
Step 7 : Mix calculations
Mix calculations per unit volume of concrete
(a) volume of concrete = 1m3
(b) Volume of cement = [mass of cement/(specific gravity of cement*1000)]
= 280/(3.15*1000)
= 0.089m3
(c) Volume of fly ash = [mass of fly ash/(specific gravity of flyash*1000)]
= 120/(2.2*10000)
= 0.055m3
(d) Volume of water = [mass of water/(specific gravity of water*1000)]
= 134.4/1000
= 0.134m3
(e) Volume of chemical admixture = [mass of chemical admixture/(specific gravity of admixture*1000)]
(Here, mass of chemical admixture is 2% of cementitious material)
Mass of admixture = (2/100)*400
= 8Kg/m3
Volume of chemical admixture = [8/(1.145*1000)]
= 0.007m3
(f) Volume of aggregate(coarse aggregate and fine aggregate) = [a-(b+c+d+e)]
= [1-(0.089+0.055+0.134+0.007)]
= 0.715m3
(g) Mass of coarse aggregate = f*volume of coarse aggregate*specific gravity of coarse aggregate*1000
= 0.715*0.57*2.74*1000
= 1116.7Kg/m3
(h) Mass of fine aggregate = f*volume of fine aggregate*specific gravity of fine aggregate*1000
= 0.715*0.43*2.74*1000
= 842.4Kg/m3
Step 8 : Mix proportion for trail1
- Cement = 280Kg/m3
- Fly ash = 120Kg/m3
- water = 134.4Kg/m3
- Fine aggregate = 842.4Kgm3
- coarse aggregate = 1116.7Kg/m3
- W/C ratio = 0.34
- Trial mix = 1:3.01:3.98 (cement:fine aggregate:coarse aggregate)
Step 9 : The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump. The mix proportion shall be reworked for actual water content and checked for durability requirements.
Step 10 : Two more trails having variation of 10% of water cement ratio in clause shall be carried out and a graph between 3 water cement ratios and corresponding strengths shall be plotted to workout the mix proportions for the given target strength for field trails. However, durability shall be met.
Concrete mix design for M50 grade concrete without fly ash.
Step 1 : Stipulations for proportioning
Grade designation : M50
Type of cement : OPC 53 grade confirming to IS8112
Maximum nominal size of aggregate : 2omm
Minimum cement content : 360 Kg/m3 (For M50 grade concrete from Table 5 of IS456:2000)
Maximum water cement ratio : 0.45 (For severe exposure from Table 5 of IS456:2000)
Workability : 100mm slump
Exposure condition : Severe (For reinforced concrete)
Method of concrete placing : pumpable concrete
Degree of supervision : Good
Type of aggregate : Crushed angular aggregate
Chemical admixture type : Super plasticizer (confirming to IS8112)
Specific gravity of cement (From manufacturer) : 3.15
Specific gravity of coarse aggregate : 2.74
Specific gravity of fine aggregate : 2.74
Water absorption for coarse aggregate : 0.5%
Water absorption for fine aggregate : 0.5%
Free surface moisture for coarse aggregate : Nil
Free surface moisture for fine aggregate : Nil
Sieve analysis for coarse aggregate : Table 2 of IS383
Sieve analysis for fine aggregate : Table 4 of IS383 (Zone 1 grading)
Step 2 : Calculation of target mean strength for mix proportioning (Ft)
Ft = Fck + 1.65S (From IS456:2000)
Where "Ft" is target mean strength of concrete to be designed
"Fck" is compressive strength of concrete grade
"S" is standard deviation
Ft = 50N/mm2(for M35 grade concrete) + (1.65*5)[For M35 grade concrete standard deviation is 5 from Table 2 of IS10262:2019]
Ft = 58.25N/mm2
Step 3 : Selection of water cement ratio
From graph of IS10262:2019, W/C ratio for target mean strength of 58.25N/mm2 and for OPC 53 grade of cement (curve 3 of graph)
W/C = 0.34
From table 5 of IS456:2000, W/C ratio for severe exposure condition is 0.5
W/C = 0.45
Minimum of both values is considered as actual water cement ratio, Which is
W/C = 0.34
Step 4 : Selection of water content
From Table 4 of IS10262:2019, for 20mm maximum nominal size of aggregate,
Maximum water content = 186L (for 25mm to 50mm slump)
Estimated water content for 100mm slump is (According to the same code approximate of 3% increase in water content is required for increase of 25mm slump)
= 186 + [(6/100)*186]
Estimated water content for 100mm slump is = 197L
As super plasticizer is used, water content is decreased by 29%
Hence, the final water content for 100mm slump with 20mm maximum nominal size of aggregate and with super plasticizer is = [197*(100-29)]/100]
= 140L
Water content = 140L
Step 5 : Calculation of cement content
W/C ratio = 0.34
140/C =0.34
C = 140/0.34
Cement content = 350 Kg/m3
(From IS456:2000, Table 5 Minimum cement content for M50 grade is 360Kg/m3 and for severe exposure condition, it is 360Kg/m3)
350<360Kg/m3
Revised cement content = 360Kg/m3
Revised W/C ratio = 140/360 = 0.39
Minimum valuse should be considered
W/c ratio = 0.34
Step 6 : Proportion of volume of coarse aggregate and fine aggregate content
From Table 5 of IS10262:2019,volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone1) for W/C ratio of 0.5 = 0.6
In ths case W/C ratio is 0.34, hence the volume of coarse aggregate is (for decrease of every 0.1 in W/C ratio, the proportion of volume of coarse aggregate is increased by 0.01)
= [(0.5-W/C)*0.01]/0.05+volume of coarse aggregare from table
= [(0.5-0.34)*0.01]/0.05+0.6
= 0.632
Corrected volume of coarse aggregate is = 0.632
For pumpable concrete, volume of coarse aggregate (is reduced by 10%) = 0.632*[(100-10)/100]
Volume of coarse aggregate= 0.57
Volume of fine aggreagte = 1- volume of coarse aggregate = 1-0.57
Volume of fine aggregate = 0.43
Step 7 : Mix calculations
Mix calculations per unit volume of concrete
(a) volume of concrete = 1m3
(b) Volume of cement = [mass of cement/(specific gravity of cement*1000)]
= 360/(3.15*1000)
= 0.1142m3
(c) Volume of water = [mass of water/(specific gravity of water*1000)]
= 140/1000
= 0.14m3
(d) Volume of chemical admixture = [mass of chemical admixture/(specific gravity of admixture*1000)]
(Here, mass of chemical admixture is 2% of cementitious material)
Mass of admixture = (2/100)*360
= 7.2Kg/m3
Volume of chemical admixture = [7.2/(1.145*1000)]
= 0.0082m3
(e) Volume of aggregate(coarse aggregate and fine aggregate) = [a-(b+c+d)]
= [1-(0.1142+0.14+0.0082)]
= 0.738m3
(f) Mass of coarse aggregate = e*volume of coarse aggregate*specific gravity of coarse aggregate*1000
= 0.738*0.57*2.74*1000
= 1152.61Kg/m3
(g) Mass of fine aggregate = e*volume of fine aggregate*specific gravity of fine aggregate*1000
= 0.738*0.43*2.74*1000
= 869.5Kg/m3
Step 8 : Mix proportion for trail1
- Cement = 360Kg/m3
- water = 140Kg/m3
- Fine aggregate = 869.5Kgm3
- coarse aggregate = 1152.61Kg/m3
- W/C ratio = 0.34
- Trial mix = 1:2.42:3.21 (cement:fine aggregate:coarse aggregate)
Step 9 : The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump. The mix proportion shall be reworked for actual water content and checked for durability requirements.
Step 10 : Two more trails having variation of 10% of water cement ratio in clause shall be carried out and a graph between 3 water cement ratios and corresponding strengths shall be plotted to workout the mix proportions for the given target strength for field trails. However, durability shall be met.