Project on Concrete Mix Design for various grades of Concrete
Concrete Mix Design for M35 grade with fly ash:
1.Stipulations for Mix Design Concrete:
a.Grade designation : M35
b.Type of cement : OPC 53 grade conforming to IS 8112
c. Type of mineral admixture : Fly ash conformong to IS 3812 (Part 1)
d.Maximum nominal size of aggregates : 20mm
e.Minimum cement content : 340 kg/m3
f.Maximum water-cement ratio : 0.45
g.Workability : 50-100mm (Slump)
h.Exposure condition : Very severe (for reinforced concrete)
i.Method of concrete placing : Pumping
j.Degree of supervision : Good
k.Type of aggregate : Crushed angular aggregate
l.Maximum cement content : 450 kg/m3
m.Chemical admixture type : Super plasticizers
2.Test data for materials (to be determined in the laboratory)
a.Cement used : OPC 43 grade confirming to IS 8112
b.Specific gravity of cement : 3.12
c.Fly ash : Conforming to IS 3812 (Part 1)
d.Specific gravity of fly ash : 2.2
e.Chemical admixture : Super plasticizers conforming to IS 9103
f.Specific gravity of
Coarse aggregate : 2.74
Fine aggregate : 2.56
g.Water absorption:
Coarse aggregate : 0.5%
Fine aggregate : 1%
h.Free surface moisture:
Coarse aggregate : Nil
Fine aggregate : Nil
i.Sieve analysis : Fine aggregate conforming to grading zone II of Table 4 of IS 383
3.Target strength for mix proportioning:
f'ck = fck + 1.65xS
where,
f'ck = target mean compressive strength of concrete at 28 days in N/mm2
fck = characteristics compressive strength of concrete at 28 days in N/mm2
S = standard deviation from Table 8 of IS 10262 : 2009 (For M35 grade S= 5 N/mm2)
f'ck = 35 + 1.65 x 5
= 43.25 N/mm2
Therefore, the target strength = 43.25 N/mm2
4.Selection of water-cement ratio:
From Table 5 of IS 456 : 2000, by exposure condition.
Here very severe condition is considered, the maximum water content = 0.45
5. Selection of water content:
From Table 2 of IS 456, maximum water content = 186 litres (for 25 to 50mm slump range) for 20mm aggrgate.
Estimated water content for 100mm slump = 186 + (6/100) x 186 = 197 litres
(Note: If super plasticizer is used, the water content can be reduced upto 20% and above).
Based on trial with super plasticizer water content reduction of 25% has been achieved. Hence the arrived water content = 197 - {197x(25/100)} = 147 litres.
6.Calculation of cement content:
Water-cement ratio = 0.45
Cementatious material (Cement + Fly ash) = 147/0.45 = 350 kg/m3
From Table 5 of IS 456, minimum cement content for very severe exposure condition = 340 kg/m3
350 kg/m3 > 340 kg/m3, Hence ok.
To proportion the mix containing fly ash the following steps are suggested:
a.The percentage of fly ash need to be decided based on project requirement and quality of materials.
b.In same 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 x 1.10 = 385 kg/m3
Water content = 147 kg/m3
Hence, water-cement ratio = 147/385 = 0.381
Fly ash at 30% of total cementatious material content = 35 - 30% = 385 x 0.30 = 115 kg/m3
Cement (OPC) = 385 - 115 = 270 Kg/m3
Saving of cement while using fly ash = 350 - 270 = 80 kg/m3
Fly ash being utilized = 115 kg/m3
Calculation of super plasticizers content @ 0.6% weight of cementatious content = (0.6/100) x 385 = 2.31 kg
7.Proportion of the volume of coarse aggregate and fine aggregate content:
From Table 3 of IS 10262: 2009, volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone II) for a water-cement ratio of 0.50 = 0.62.
In the present case, the water-cement ratio is 0.45. Therefore, the volume of coarse aggregate is required to be increased to reduce the fine aggregate content.
As the water-cement ratio is lower by 0.05, the proportion of the volume of coarse aggregate is increased by 0.01 (at the rate of +/- 0.01 for every +/- 0.05 change in the water-cement ratio). Therefore, the corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.45 = 0.63.
Note: In case the coarse aggregate is not angular one, then also volume of coarse aggreagte may be required 10 % to be increased suitably, based on experience.
For pumpable concrete, these values should be reduced by 10%.
Therefore, volume of coarse aggregate = 0.63 x 0.90 = 0.567
Volume of fine aggregate = 1 - 0.567 = 0.433
8.Mix calculation:
a.Volume of concrete = 1 m3
b.Volume of cement = (Mass of cement / Specific gravity of cement) x (1/1000)
= (270 / 3.12) x (1/1000)
= 0.086 m3
c.Volume of fly ash = (Mass of fly ash / Specific gravity of fly ash) x (1/1000)
= (115 / 2.2) x (1/1000)
= 0.052 m3
d.Volume of water = (Mass of water / Specific gravity of water) x (1/1000)
= (147/1) x (1/1000)
= 0.147 m3
e.Volume of chemical admixture = (Mass of admixture / Specific gravity of admixture) x (1/1000)
= (2.31/1.14) x (1/1000)
= 0.002 m3
f.Volume of all in aggregate = (a-(b+c+d+e))
= (1 - (0.086+0.052+0.147+0.002))
= 0.713 m3
g.Mass of coarse aggragate = f x volume of coarse aggregate x specific gravity of coarse aggregate x 1000
= 0.713 x 0.567 x 2.74 x 1000
= 1108 kg/m3
h.Mass of fine aggregate = f x volume of fine aggregate x specific gravity of fine aggregate x 1000
= 0.713 x 0.433 x 2.56 x 1000
= 790 kg/m3
9.Mix proportion:
Cement = 270 kg/m3
Fly ash = 115 kg/m3
Water = 147 kg/m3
Fine aggregate = 790 kg/m3
Coarse aggregate = 1108 kg/m3
Chemical admixture = 2.31 kg/m3
Water-cement ratio = 0.381
Mix ratio = 1: 2.05 : 2.87
Concrete Mix Design for M50 grade without fly ash:
1.Stipulations for Mix Design Concrete:
a.Grade designation : M50
b.Type of cement : OPC 53 grade conforming to IS 8112
c.Maximum nominal size of aggregates : 20mm
d.Minimum cement content : 320 kg/m3
e.Maximum water-cement ratio : 0.45
f.Workability : 50-100mm (Slump)
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/m3
l.Chemical admixture type : Super plasticizers
2.Test data for materials (to be determined in the laboratory)
a.Cement used : OPC 43 grade confirming to IS 8112
b.Specific gravity of cement : 3.15
c.Chemical admixture : Super plasticizers conforming to IS 9103
d.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.Sieve analysis : Fine aggregate conforming to grading zone I of Table 4 of IS 383
3.Target strength for mix proportioning:
f'ck = fck + 1.65xS
where,
f'ck = target mean compressive strength of concrete at 28 days in N/mm2
fck = characteristics compressive strength of concrete at 28 days in N/mm2
S = standard deviation from Table 8 of IS 10262 : 2009 (For M50 grade S= 5 N/mm2)
f'ck = 50 + 1.65 x 5
= 58.25 N/mm2
Therefore, the target strength = 58.25 N/mm2
4.Selection of water-cement ratio:
From Table 5 of IS 456 : 2000, by exposure condition.
Here severe condition is considered, the maximum water content = 0.45
Based on experience, consider water-cement ratio = 0.40
5. Selection of water content:
From Table 2 of IS 456, maximum water content = 186 litres (for 25 to 50mm slump range) for 20mm aggrgate.
Estimated water content for 100mm slump = 186 + (6/100) x 186 = 197 litres
(Note: If super plasticizer is used, the water content can be reduced upto 20% and above).
Based on trial with super plasticizer water content reduction of 30% has been achieved. Hence the arrived water content = 197 - {197x(30/100)} = 138 litres.
6.Calculation of cement content:
Water-cement ratio = 0.40
Cement content = 138/0.40 = 345 kg/m3
From Table 5 of IS 456, minimum cement content for severe exposure condition = 320 kg/m3
345 kg/m3 > 320 kg/m3, Hence ok.
Calculation of super plasticizers content @ 0.6% weight of cement content = (0.6/100) x 345 = 2.07 kg
7.Proportion of the volume of coarse aggregate and fine aggregate content:
From Table 3 of IS 10262: 2009, volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (Zone I) for a water-cement ratio of 0.50 = 0.60.
In the present case, the water-cement ratio is 0.40. Therefore, the volume of coarse aggregate is required to be increased to reduce the fine aggregate content.
As the water-cement ratio is lower by 0.10, the proportion of the volume of coarse aggregate is increased by 0.02 (at the rate of +/- 0.01 for every +/- 0.05 change in the water-cement ratio). Therefore, the corrected proportion of volume of coarse aggregate for the water-cement ratio of 0.40 = 0.62.
Note: In case the coarse aggregate is not angular one, then also volume of coarse aggreagte may be required 10 % to be increased suitably, based on experience.
For pumpable concrete, these values should be reduced by 10%.
Therefore, volume of coarse aggregate = 0.62 x 0.90 = 0.558
Volume of fine aggregate = 1 - 0.558 = 0.442
8.Mix calculation:
a.Volume of concrete = 1 m3
b.Volume of cement = (Mass of cement / Specific gravity of cement) x (1/1000)
= (345 / 3.15) x (1/1000)
= 0.109 m3
c.Volume of water = (Mass of water / Specific gravity of water) x (1/1000)
= (138/1) x (1/1000)
= 0.138 m3
d.Volume of chemical admixture = (Mass of admixture / Specific gravity of admixture) x (1/1000)
= (2.07/1.145) x (1/1000)
= 0.002 m3
e.Volume of all in aggregate = (a-(b+c+d))
= (1 - (0.109+0.138+0.002))
= 0.751 m3
f.Mass of coarse aggragate = e x volume of coarse aggregate x specific gravity of coarse aggregate x 1000
= 0.751 x 0.558 x 2.74 x 1000
= 1148 kg/m3
h.Mass of fine aggregate = e x volume of fine aggregate x specific gravity of fine aggregate x 1000
= 0.751 x 0.442 x 2.74 x 1000
= 910 kg/m3
9.Mix proportion:
Cement = 345 kg/m3
Water = 138 kg/m3
Fine aggregate = 910 kg/m3
Coarse aggregate = 1148 kg/m3
Chemical admixture = 2.07 kg/m3
Water-cement ratio = 0.40
Mix ratio = 1: 2.64 : 3.33