Project on Concrete Mix Design for various grades of Concrete
Aim: Mix design for M 35 grade concrete with fly ash
Procedure:
Step :1
Stipulations for proportioning
a. Grade designation : M35
b. Type of cement: OPC 43 grade conforming to IS 8112
c. Type of mineral admixture: Fly ash confirming to IS 3812 (Part
d. Maximum nominal size of aggregates: 20mm
e. Minimum cement content: 320 kg/m^3 (Table :5 IS 456-2000,based on exposure
condition)
f. Maximum water-cement ratio: 0.45 (Table 5 IS 456-2000,based on exposure
condition)
g. Workability:100mm slump value of pumpable concrete
h. Exposure condition : Severe (for reinforced concrete)
i. Method of concrete placing: Pumping
j. Degree of supervision: Good
k. Type of aggregate: Crushed angular aggregate
1. Maximum cement content: 450 kg/m3.
m. Chemical admixture type: Superplaticizer.
Step :2
Test data for materials
a. Cement used: OPC 43 grade confirming to IS 8112
b. Specific gravity of cement: 3.15
c. Fly ash: Conforming to IS 3812 part 1
d. Specific gravity of flyash : 2.2
e. Chemical admixture : Superplaticizer conforming to IS 9103.
f. Specific gravity of:
Coarse aggregate: 2.74
Fine aggregate: 2.74
g. Water absorption
Coarse aggregate: 0.5%
Fine aggregate : 1%
h. Free surface moisture
Coarse aggregate : Nil
Fine aggregate: Nil
i. Seive analysis
Coarse aggregates:
IS seive Analysis of coarse
size (mm) aggregate fraction % of different fraction remarks
I II I II combined
20 100 100 60 40 100 conforming
10 0 71.2 0 28.5 28.5 to
4.75 9.4 3.7 3.7 table-2 of
2.36 0 IS 383
Fine aggregate: Conforming to grading Zone 1 of table 4 IS 383.
Step :3
To find target mean strength for mix proportioning
Target mean strength fick = fck +1.65s
= 35 +1.65*5=43.25 N/mm²
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
20001
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
Cementatious material (Cement +flyash) = 140/0.4 =350`kg/m3`
In table 5 of IS 456-2000, the cement content for severe exposure =320 kg/m3
350 kg/m3 > 320kg/m3 Hence OK
To proportion the mix containing flyash the following steps are suggested:
a. The percentage of flyash need to be decided based on project requirement and qualityof materials.
b. In some cases increase in cementatious materials can be warned. Increase in cementatious material content and its percentage may be based on experience and
trial
In this increase of 10% cementatious material content is considered.
Cementatious material content = 350*11=385 kg/m3
Water content = 140 kg/m3
So, water- cement ratio = 140/385 -0.364
Fly ash at 30% total cementatious material content - 35-30% -115 kg/m3
Cement (OPC) -385-115 -270 kg/m3
Saving of cement while using flyash = 350-270-80 kg/m3
Fly ash beign utilized = 115 kg/m3
Step: 7
Proportion of volume of coarse aggregate and fine aggregate content
From table 3 of IS 1026:2009 volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone 1) for water-cement ratio -0.6
In present case the water cement ratio is 0.4
Therefore the volume of coarse aggregate needs to be increased to decrease the fine aggregate content.
As the water- cement ratio is lowered by 0.1 ,the proportion of volume of coarse aggregate is increased by 0.02( at the rate of +/- 0.01 for every +/- 0.05 change in water- cement ratio)
Hence the corrected value ofcoarse aggregate for the water-cemnt ratio = 0.64
(If coarse aggregate is not of angular type, then also the volume of coarse aggregate may be required to be increased suitably based on experience)
For pumpable concrete, these are reduced by 10%
Volume of coarse aggregate = 0.64 0.9 = 0.576
Volume of fine aggregate = 1-0.576 =0.424
Step :8
Mix calculations
Mix calculation per unit volume of concrete:
a. Volume of concrete = 1 m3.
b. Volume of cement = (Mass of cement / Specific gravity of cement) *1/1000 = (270/3.15)*1/1000 =0.086 m3
c. Volume of flyash = (Mass of flyash/Specific gravity of flyash )*1/1000 = (115/2.2) 1/1000 = 0.052 m3
d. Volume of water (Mass of water/Specific gravity of water) 1/1000 = (140/1) 1/1000=0.140 m3
e. Volume of chemical admixture = (Mass of admixture / specific gravity of admixture) 1/1000 = (7.6/1.14) 1/1000 =0.006 m3
f. Volume of aggregate ( Fine and coarse) = a- (b+c+d+e) 1-(0.086+0.052+0.140+0.006) -0.716 m3
g. Mass of coarse aggregate = f*Volume of coarse aggregate*Specific gravity of coarse aggregate*1000 =0.716 0.576 2.74*1000=1130 kg/m3
h. Mass of fine aggregate = f* Volume of fine aggregate*Specific gravity of fine aggreate*1000 =0.716 0.424 2.74*1000=831 kg/m3
Step :9
Mix proportion
Cement = 270 kg/m3
Fly ash = 115 kg/m3
Water = 140 kg/m3
Fine aggregate = 831 kg/m3
Coarse aggregate = 1130 kg/m3
Chemical admixture = 7 kg/m3
Water-cement ratio = 0.364
Mix ratio 1: 2.15: 2.94
Mix design of M 50 grade concrete Aim: Mix design of M 50 grade concrete
Procedure:
Step :1
Stipulation for proportioning
a. Grade designation : M50
b. Type of cement: OPC grade 43 conforming to IS 8112
c. Maximum nominal sizeof aggregate: 20mm
d. Minimum cement content: 320
e. Maximum water-cement ratio: 0.45 (Table 5 IS 456-2000 base condition)
f. Workability:100mm slump value of pumpable concrete
g. Exposure condition: Severe for reinforced concrete)
h. Method of concrete placing Pumping
i. Degree of supervision: Good
j. Type of aggregate: Crushed angular aggregate
k. Maximum cement content: 450 kg/m^3.
L. Chemical admixture type : Superplaticizer.
Step:2
Test data for materials
a. Cement used: OPC 43 grade confirming to IS 8112
b. Specific gravity of cement: 3.15
c. Chemical admixture: Superplaticizer conforming to IS 9103
d. Specific gravity of
Coarse aggregate: 2.74
Fine aggregate: 2.74
e. Water absorption:
Coarse aggregate: 0.5%
Fine aggregate: 1%
f. Free surface moisture
Coarse aggregate : Nil
Fine aggregate : Nil
g. Seive analysis
Coarse aggregates:Conforming to table 4 of IS 383
Fine aggregate: Conforming to grading Zone 1 of table 4 IS 383.
Step:3
To find target mean strength for proportioning
Target mean strength, f'ck-fck +1.65 s
50+1.65*5-58.25 n/mm2
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 Hence OK.
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 =350 kg/m3
In table 5 of IS 456-2000, the cement content for severe exposure =320 kg/m3
350 kg/m3 > 320 kg/m3 Hence OK.
Step: 7
Proportion of volume of coarse aggregate and fine aggregate content
From table 3 of IS 1026:2009 volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone 1) for water- cement ratio -0.6
In present case the water - cement ratio is 0.4
Therefore the volume of coarse aggregate needs to be increased to decrease the fine
aggregate content.
As the water cement ratio is lowered by 0.1 ,the proportion of volume of coarse aggregate is increased by 0.02( at the rate of +/- 0.01 for every +/- 0.05 change in water-cement ratio)
Hence the corrected value of coarse aggregate for the water-cemnt ratio - 0.64
(If coarse aggregate is not of angular type, then also the volume of coarse aggregate may be required to be increased suitably based on experience)
For pumpable concrete, these are reduced by 10%
Volume of coarse aggregate = 0.64 0.9 = 0.576
Volume of fine aggregate = 1-0,576 -0.424
Step:8
Mix calculation
For unit volume of concrete
a. Volume of concrete = 1
b. Volume of cement-(Mass of cement / Specific gravity of cement) *1/1000 (350/3.15) 1/1000 =0.111 m3
C. Volume of water = (Mass of water/Specific gravity of water )*1/1000 (140/1) 1/1000 = 0.140 m3
d. Volume of chemical admixture= (Mass of admixture/Specific gravity of admixture) 1/1000 =(7.6/1.145) 1/1000 =0.006 m3
e. Volume of agggregate (fine adn coarse) = a-(b+c+d) = 1-(0.111+0.140+0.006) = 0.743 m3
f. Mass of coarse aggregate = ex Volume of coarse aggregate x Specific gravity of coarse aggregate x 1000 =0.743 0.576 2.74*1000= 1173 kg/m3
g. Mass of fine aggregate =e* Volume of fine aggregate* Specific gravity of fine aggregate 1000 = 0.743*0,424*2.74*1000 = 863 kg/m3
Step :9
Mix proportion
Cement = 350 kg/m3
Water = 140 kg/m3
Fine aggregate= 863 kg/m3
Coarse aggregate = 1173 kg/m3
Chemical admixture = 7 kg/m3
Water cement ratio =0.4
Mix ratio=1: 2.46: 3.35