Project on Concrete Mix Design for various grades of Concrete
Q.1.
Concrete Mix design for M35 grade concrete with Flyash:
Aim:
To perform mix design process for M35 grade concrete with Flyash as mineral admixture.
Introduction:
Concrete mix design is the procedure of selecting the suitable ingradients of concrete and their relative proportions to prepare concrete mix with suitable Compressive strength and durability.
Flyash is the mineral admixture that partially raplaces the cement content in the concrete mix. Flyash is the by product occurs at Thermal power plants. It is easily available and most economical mineral admixture.
Procedure:
1.Stipulations for proportioning of Concrete ingradients:
a.Grade designation : M35
b.Type of Cement : OPC 43 (Confirming to IS 8112)
c.Type of mineral admixture: Flyash (confirming to IS 3812 Part 1)
d.Maximum nominal size of Aggregate: 20mm
e.Minimum cement content and maximum water cement ratio to be adopted based on exposure condition i.e. Severe.
(from table 5 of IS 456-2000)=320kg/m3.
f. Method of Concrete placing: Pumping
g.Workability: 100mm (Slump for Pumpable concrete)
h.Degree of supervision: Good
i. Type of Aggregate: Crushed angular aggregate
j.Maximum cement content: 450kg/m3 (from clause 8.2.4.2,IS 456-2000)
k.Chemical admixture: Super plasticizer (confirming to IS 9103)
2.Test data for Materials:
a.Cement: OPC 43 grade
b.Specific gravity of Cement: 3.15
c.Flyash: Confirming to IS 3812 part 1)
d.Specific gravity of flyash: 2.2
e.Chemical admixture: Super plasticizer (confirming to IS 9103)
f.Specific gravity of
Coarse aggregate: 2.74
Fine aggregate: 2.65
Chemical admixture: 1.145
Note: Specific gravity of coarse aggregate and fine aggregate is taken at Saturated surface condition.
g.Water absorption: for corse aggregate:0.5%
for fine aggregate : 1%
h.Surface moisture: for Coarse aggregate: Nil
for fine aggregate : Nil
i.Sieve Analysis:
Corase aggregate:
| IS sieve size (mm) | Analysis of Coarse aggregate fraction | Percentage of different fractions | Remarks |
| I II | I II Combined(100%) | ||
| 20 | 100 100 | 60 40 100 | Confirming to Table 2 of IS 383 |
| 10 | 0 71.2 | 0 28.5 28.5 | |
| 4.75 | 9.4 | 3.7 3.7 | |
| 2.36 | 0 |
Fine Aggregate: Confirming to grading zone 1 of table4 of IS 383
3.Target Mean Strength:
Fck'=Fck+1.65S
where, Fck'=Target mean strength of concrete at 28 days
Fck=Characteristic compressive strength at 28 days
S =Standard deviation
From table 1 of IS 10262-2009, Standard deviation for M35 grade concrete=5
Therefore, Fck'=35+(1.65*5)=43.25N/mm2.(Target mean strength)
4.Selection of Water Cement ratio:
From table 5 of IS 456-2000, for Severe exposure condition,maximum Water-cement ratio=0.45.
Based on expierence, selected water cement ratio will be 0.40.
Here, minimum value is 0.40. Therefore adopted water cement ratio=0.40
5.Selection of Water content:
From table 2 of IS 10262-2009, maximum water content for 20mm aggregate=186 litres.(for 25mm to 50mm slump range)
Note: For every 25mm increased in slump range, 3% water content should be added to adopted water content.
Hence for 100mm slump, 6% should be added.
Estimated water content for 100mm slump=186+(6/100)*186=197 litres.
Note: As super plasticizer is used, water content should be reduced upto 30%
Therefore, final adopted water content=197*0.7=140 litres (approximately).
6.Caluculation of Cement content:
As Water cement ratio=0.4,
Cementitious material (Cement+Flyash)=140/0.4=350Kg/m3
From table 5 of IS 456-2000. minimum cement content for severe exposure condition is 320kg/m3.
Here 350>320. hence OK.
7.Caluculation of Flyash content:
The percentage of Flyash content needs to be decided based on site conditions and requirement and trial basis.
Here increasing cementitious material upto 10%.
Increased cementitious material=350*1.1=385Kg/m3
Water content=140 litres
Water cement ratio=140/385=0.364.
Note: As per IS 456-2000, the maximum replacement of cement with flyash have a capping of 35%.
Flyash @ 30% of total cementitious material=385*30%=115Kg/m3.
Cement content =385-115=270Kg/m3.
Therefore saving of cement by using Flyash =350-270=80Kg/m3.
Flyash being utilized=115Kg/m3.
8.Caluculation of Coarse aggregate and Fine aggregate:
From table 3 of IS 10262-2009,
Volume of Corase aggregate corresponding to 20mm aggregate and fine aggregate of Zone 1 for water cement ratio of 0.5=0.6.
In present case Water cement ratio=0.4, therefore volume of coarse aggregate needs to increse to decrease the fine aggregate content.
As water cement ratio is lower by 0.1, Coarse aggregate should increase by 0.02 (at the rate of +/-0.01 for every +/-0.05 change in W/C ratio).
Therefore corrected volume of corase aggregate=0.62.
Note: In case of Coarse aggregate is not angular one, then also volume of CA need to increase based on expierence.
For Pumpable concrete, these values should be reduced by 10%.
Therefore, Volume of Corase aggregate=0.62*0.9=0.56.
Volume of Fine aggregate =1-0.56=0.44.
9.Mix Caluculatios:
The mix caluculations per unit volume of concrete shall be as follows:
a.Volume of Concrete =1m3
b.Volume of Cement =(Mass of cement/Specific gravity of cement)*(1/1000)
= (270/3.15)*(1/1000)
= 0.086m3.
c.Volume of Flyash =(Mass of flyash/Specific gravity of flyash)*(1/1000)
= (115/2.2)*(1/1000)
=0.052m3.
d.Volume of Water =(Mass of water/Specific gravity of water)*(1/1000)
=(140/1)*(1/1000)
=0.140m3
e.Volume of Chemical admixture = (Mass of admixture/Specific gravity of Admixture)*(1/1000)
(@ 2% of mass of cementitious material)
= (7.5/1.145)*(1/1000)
=0.006m3
f.Volume of Aggregate = a-(b+c+d+e)
=1-(0.086+0.052+0.140+0.006)
=0.716 m3.
g.Volume of Coarse aggregate= f*volume of coarse aggregate*specific gravity of coarse aggregate*1000
= 0.716*0.56*2.74*1000
= 1098kg/m3
h.Volume of Fine aggregate = f*volume of fine aggregate*specific gravity of fine aggregate*1000
= 0.716*0.44*2.65*1000
=835Kg/m3.
10.Mix Proportions for Trial 1:
Cement: 270kg/m3
Flyash=115kg/m3
Water=140kg/m3
Chemical admixture=7.5kg/m3
Coarse aggregate=1098kg/m3
Fine aggregate=835kg/m3
Water cement ratio= 0.364.
Result:
The mix design for M35 grade concrete with Flyash is 1:2.16:2.85.
Referrences:
Codes : IS 456-2000, IS 10262-2009, IS 383, IS 8112, IS 3812 part1, IS 9103.
Q.2:
Mix design for M50 grade concrete with out Flyash
Aim:
To perform mix design process for M50 grade concrete without flyash
Introduction:
Concrete mix design is the procedure of selecting the suitable ingradients of concrete and their relative proportions to prepare concrete mix with suitable Compressive strength and durability.
Procedure:
1.Stipulations for proportioning of Concrete ingradients:
a.Grade designation : M50
b.Type of Cement : OPC 43 (Confirming to IS 8112)
c.Maximum nominal size of Aggregate: 20mm
d.Minimum cement content and maximum water cement ratio to be adopted based on exposure condition i.e. Severe (for reinforced concrete),(from table 5 of IS 456-2000)
Minimum cement content=320kg/m3 and maximum water cement ratio=0.45.
e. Method of Concrete placing: Pumping
f. Workability: 100mm (Slump for Pumpable concrete)
g.Degree of supervision: Good
h. Type of Aggregate: Crushed angular aggregate
i.Maximum cement content: 450kg/m3 (from clause 8.2.4.2,IS 456-2000)
j.Chemical admixture: Super plasticizer (confirming to IS 9103).
2.Test data for Materials:
a.Cement: OPC 43 grade
b.Specific gravity of Cement: 3.15
c.Chemical admixture: Super plasticizer (confirming to IS 9103)
d.Specific gravity of
Coarse aggregate: 2.74
Fine aggregate: 2.74
Chemical admixture: 1.145
e.Water absorption: for corse aggregate:0.5%
for fine aggregate : 1%
f.Surface moisture: for Coarse aggregate: Nil
for fine aggregate : Nil
g.Sieve Analysis:
Corase aggregate:
| IS sieve size (mm) | Analysis of Coarse aggregate fraction | Percentage of different fractions | Remarks |
| I II | I II Combined(100%) | ||
| 20 | 100 100 | 60 40 100 | Confirming to Table 2 of IS 383 |
| 10 | 0 71.2 | 0 28.5 28.5 | |
| 4.75 | 9.4 | 3.7 3.7 | |
| 2.36 | 0 |
Fine Aggregate: Confirming to grading zone 1 of table4 of IS 383.
3.Target Mean Strength:
Fck'=Fck+1.65S
where, Fck'=Target mean strength of concrete at 28 days
Fck=Characteristic compressive strength at 28 days
S =Standard deviation
From table 1 of IS 10262-2009, Standard deviation for M50 grade concrete=5
Therefore, Fck'=50+(1.65*5)=58.25N/mm2.(Target mean strength).
4.Selection of Water Cement ratio:
From table 5 of IS 456-2000, for Severe exposure condition,maximum Water-cement ratio=0.45.
Based on expierence, selected water cement ratio will be 0.40.
Here, minimum value is 0.40. Therefore adopted water cement ratio=0.40.
5.Selection of Water content:
From table 2 of IS 10262-2009, maximum water content for 20mm aggregate=186 litres.(for 25mm to 50mm slump range)
Note: For every 25mm increased in slump range, 3% water content should be added to adopted water content.
Hence for 100mm slump, 6% should be added.
Estimated water content for 100mm slump=186+(6/100)*186=197 litres.
Note: As super plasticizer is used, water content should be reduced upto 30%
Therefore, final adopted water content=197*0.7=140 litres (approximately).
6.Caluculation of Cement content:
As Water cement ratio=0.4,
Cement content=140/0.4=350Kg/m3
From table 5 of IS 456-2000. minimum cement content for severe exposure condition is 320kg/m3.
Here 350>320. hence OK.
7.Caluculation of Coarse aggregate and Fine aggregate:
From table 3 of IS 10262-2009,
Volume of Corase aggregate corresponding to 20mm aggregate and fine aggregate of Zone 1 for water cement ratio of 0.5=0.6.
In present case Water cement ratio=0.4, therefore volume of coarse aggregate needs to increse to decrease the fine aggregate content.
As water cement ratio is lower by 0.1, Coarse aggregate should increase by 0.02 (at the rate of +/-0.01 for every +/-0.05 change in W/C ratio).
Therefore corrected volume of corase aggregate=0.62.
Note: In case of Coarse aggregate is not angular one, then also volume of CA need to increase based on expierence.
For Pumpable concrete, these values should be reduced by 10%.
Therefore, Volume of Corase aggregate=0.62*0.9=0.56.
Volume of Fine aggregate =1-0.56=0.44.
8.Mix Caluculatios:
The mix caluculations per unit volume of concrete shall be as follows:
a.Volume of Concrete =1m3
b.Volume of Cement =(Mass of cement/Specific gravity of cement)*(1/1000)
= (350/3.15)*(1/1000)
= 0.111m3.
c.Volume of Water =(Mass of water/Specific gravity of water)*(1/1000)
=(140/1)*(1/1000)
=0.140m3
d.Volume of Chemical admixture = (Mass of admixture/Specific gravity of Admixture)*(1/1000)
(@ 2% of mass of cementitious material)
= (7/1.145)*(1/1000)
=0.006m3
e.Volume of Aggregate = a-(b+c+d)
=1-(0.111+0.140+0.006)
=0.743m3.
f.Volume of Coarse aggregate= e*volume of coarse aggregate*specific gravity of coarse aggregate*1000
= 0.743*0.56*2.74*1000
= 1140kg/m3
g.Volume of Fine aggregate = e*volume of fine aggregate*specific gravity of fine aggregate*1000
= 0.743*0.44*2.74*1000
=896Kg/m3.
9.Mix Proportions for Trial 1:
Cement: 350kg/m3
Water=140kg/m3
Chemical admixture=7kg/m3
Coarse aggregate=1140kg/m3
Fine aggregate=896kg/m3
Water cement ratio= 0.40.
Result:
The mix design for M50 grade concrete without Flyash is 1:2.55:3.25.
Referrences:
Codes : IS 456-2000, IS 10262-2009, IS 383, IS 8112, IS 9103.