Project on Concrete Mix Design for various grades of Concrete
Calculate the Concrete Mix Design for M35 grade concrete with fly ash ?
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 conforming to IS 3812 (Part 1)
d) Maximum nominal size of aggregate: 20 mm
e) Minimum cement content : 320 kg/m^3 (From Table 5 of IS 456: 2000 - Exposure condition severe)
f) Maximum water-cement ratio: 0.45 (From Table 5 of IS 456: 2000 - Exposure condition severe)
g) Workability: 100 mm (slump value for pumpable concrete)
h) Exposure condition: Severe (for reinforced concrete)
h) Method of concrete placing: Pumping
i) Degree of supervision: Good
j) Type of aggregate: Crushed angular aggregate
1) Chemical admixture type : Superplasticizer
II. Test data for materials:
a) Cement used: OPC 43 grade conforming to IS 8112
b) Specific gravity of cement: 3.15
c) Fly ash: Conforming to IS 3812 (Part 1)
d) Specific gravity of fly ash: 2.2
e) Chemical admixture: Superplasticizer conforming to IS 9103
f) Specific gravity of:
• Coarse aggregate: 2.74
• Fine aggregate: 2.74
Water absorption:
- Coarse aggregate: 0.5%
- Fine aggregate :1.0%
:1.0%
e) Free Surface moisture:
4 Coarse aggregate:Nil
Fine aggregate:Nil
III. Target Strength for Mix proportioning:
f'ck = fck +1.65 S
Where, f'ck = Target average compressive strength at 28 days
fck = Characteristic compressive strength at 28 days
S = Standard deviation
From Table 1 of IS 10262: 2009, standard deviation, S = 5 N/mm^2
Therefore, Target strength = 35+1.65 x 5 = 43.25 N/mm^2
IV. Selection of Water-cement ratio:
From Table 5 of IS 456: 2000 for severe exposure, maximum water-cement ratio = 0.45
Based on experience, adopt the water-cement ratio as 0.40
Water cement ratio from the graph( 28days strenght vs wc ratio) = 0.33
Water cement ratio from the graph ( 28days strenght vs 7 days strength cement ) = 0.41
take which ever is least heance w/c =0.33
0.33 < 0.45
V. Selection of Water content
From Table 2 of IS 10262: 2009, maximum water content for 20mm aggregate = 186 liters (for
25mm to 50mm slump range)
Estimated water content for 100mm slump = 186 + 6/100 *186
= 197 litre
As a superplasticizer is used, the water content can be reduced by up to 30%
Based on trials water content reduction of 29% is achieved with a plasticizer.
Hence the arrived water content = 197*0.71 = 140 litre
VI. Calculation of Cement Content:
Water-cement ratio = 0.33
Cementitious material (cement + fly ash)content = 140/0.33 = 424 kg/m^3
From Table 5 of IS 456 minimum cement content for 'severe' exposure condition = 320 kg/m^3
424 kg/m^3 > 320 kg/m^3, Hence OK
Now, to proportion a mix containing fly ash the following steps are suggested:
a) The percentage of fly ash needs to be decided based on project requirement and quality of materials
b) In some cases increase in cementitious material can be warranted. Increase in cementitious material content and its
percentage may be based on experience and trial (This example is with increase of 10% cementitious material content) based
on experience.
Cementitious material content = 424x 1.10 = 466.64 Kg/m^3
Water content= 140 Kg/m^3
So, the Water-cement ratio= 140/466.64 = 0.30
Fly ash @30% total cementitious material content = 466.24 x 30% = 140 Kg/m^3
Cement (OPC)= 466-140 = 326 Kg/m^3
Saving of cement while using fly ash= (424.24-326) = 98.24 Kg/m^3 and
Fly ash being utilized= 140 Kg/m^3
VII. Proportion of Volume of coarse aggregate and fine aggregate content: From Table 3 of IS 10262: 2009, Volume of coarse
aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone I) for water-cement ratio of 0.5 = 0.6
In the present case the water cement ratio is 0.33
Therefore, the volume of coarse aggregate needs to be increased to decrease 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 water-cement ratio).
Therefore, the corrected volume of coarse aggregate for the water-cement ratio of 0.33- 0.63
(Note: If the 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 values are reduced by 10%
Therefore, volume of coarse aggregate = 0.62*0.9 = 0.567.
Volume of fine aggregate content = 1 -0.567 = 0.433.
VIII. Mix Calculations:
The mix calculation per unit volume of concrete shall be as follows:
a) Volume of Concrete = 1 m^3
b) Volume of Cement =Mass of cement X Specific gravity of cement 1000
Volume of Cement. = 326/3.15 x 1/1000
= 0.103 m^3
c) Volume of Fly ash = Mass of fly ash x Specific gravity of fly ash
Volume of Fly ash = 140/2.2 x 1/1000
= 0.063 m^3
d) Volume of water
Mass of water x Specific gravity of water 1000
=140/1 * 1 / 1000
=0.14m^ 3
e) Volume of chemical admixture Specific gravity of admixture 1000
Mass of chemical admixture 1
=7.6/1.145 * 1 / 1000
=0.006m^ ^ 3
f) Volume of aggregate (FA & CA) =(a - (b + c + d + e))
=(1 - (0.103 + 0.063 + 0.14 + 0.006))
=0.688m^ ^ 3
Construction Materials/Concrete Mix Design
g) Mass of Coarse aggregate = fx Volume of coarse aggregate x Specific gravity of
coarse aggregate X 1000
= 0.688 x 0.56 x 2.74 x 1000
= 1055.66 Kg/m^3
h) Mass of fine aggregate=fx Volume of fine aggregate x Specific gravity of fine aggregate X1000
= 0.688 x 0.44 x 2.74 x 1000
= 828.45 Kg/m^3
IX. Mix proportions for Trial Number 1:
Cement= 326 Kg/m^3
Fly ash= 140 Kg/m^3
Water= 140 Kg/m^3
Fine aggregate= 828.45 Kg/m^3
Coarse aggregate = 1055.66 Kg/m^3
Chemical admixture = 7 Kg/m^3
Water-cement ratio = 0.33
Trial Mix Ratio= 1: 2.54 : 3.23
Construction Materials/Concrete Mix Design
X. The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required
slump on trial. The mix proportion shall be reworked for the actual water content and checked for durability requirements.
XI. Two more trials having variation of 10% of water-cement ratio in Clause X shall be carried out and a graph between three
water-cement ratios 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.
Concrete Mix Design for M50 grade concrete without Fly ash:
a) Grade designation: M50
b) Type of cement : OPC 43 grade conforming to IS 8112
c) Type of mineral admixture: Fly ash conforming to IS 3812 (Part 1)
d) Maximum nominal size of aggregate: 20 mm
e) Minimum cement content: 320 kg/m^3 (From Table 5 of IS 456: 2000 - Exposure condition severe)
f) Maximum water-cement ratio: 0.45 (From Table 5 of IS 456: 2000 - Exposure condition severe)
g) Workability: 100 mm (slump value for pumpable concrete)
h) Exposure condition: Severe (for reinforced concrete)
h) Method of concrete placing: Pumping
i) Degree of supervision: Good
j) Type of aggregate: Crushed angular aggregate
1) Chemical admixture type : Superplasticizer
II. Test data for materials:
a) Cement used: OPC 43 grade conforming to IS 8112
b) Specific gravity of cement: 3.15
c) Fly ash: Conforming to IS 3812 (Part 1)
d) Specific gravity of fly ash: 2.2
e) Chemical admixture: Superplasticizer conforming to IS 9103
f) Specific gravity of:
• Coarse aggregate: 2.74
• Fine aggregate: 2.74
Water absorption:
- Coarse aggregate: 0.5%
- Fine aggregate :1.0%
:1.0%
e) Free Surface moisture:
Coarse aggregate:Nil
Fine aggregate:Nil
III. Target Strength for Mix proportioning:
f'ck = fck +1.65 S
Where, f'ck = Target average compressive strength at 28 days
fck = Characteristic compressive strength at 28 days
S = Standard deviation
From Table 1 of IS 10262: 2009, standard deviation, S = 5 N/mm^2
Therefore, Target strength = 50+1.65 x 5 = 58.25N/mm^2
IV. Selection of Water-cement ratio:
From Table 5 of IS 456: 2000 for severe exposure, maximum water-cement ratio = 0.45
Based on experience, adopt the water-cement ratio
Water cement ratio from the graph( 28days strenght vs wc ratio) = 0.3
Water cement ratio from the graph ( 28days strenght vs 7 days strength cement ) = 0.34
take which ever is least heance w/c =0.3
0.3 < 0.45
V. Selection of Water content
From Table 2 of IS 10262: 2009, maximum water content for 20mm aggregate = 186 liters (for
25mm to 50mm slump range)
Estimated water content for 100mm slump = 186 + 6/100 *186
= 197 litre
As superplasticizer is used, the water content can be reduced up to 30%
Based on trials water content reduction of 29% is achieved with plasticizer.
Hence the arrived water content = 197*0.71 = 140 litre
VI. Calculation of Cement Content:
Water-cement ratio = 0.3
Cementitious material (cement + fly ash)content = 140/0.3 = 466.67kg/m^3
From Table 5 of IS 456 minimum cement content for 'severe' exposure condition = 320 kg/m^3
466.67 kg/m^3 > 320 kg/m^3, Hence OK
Now, to proportion a mix containing fly ash the following steps are suggested:
Water content= 140 Kg/m^3
So, the Water-cement ratio = 140/466.64 = 0.30
Fly ash @30% total cementitious material content = 466.24 x 30% = 140 Kg/m^3
Cement (OPC) = 466.67Kg/m^3
VII. Proportion of Volume of coarse aggregate and fine aggregate content: From Table 3 of IS 10262: 2009, Volume of coarse
aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone I) for the water-cement ratio of 0.5 = 0.6
In the present case, the water-cement ratio is 0.30
Therefore, the volume of coarse aggregate needs to be increased to decrease 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 water-cement ratio).
Therefore, the corrected volume of coarse aggregate for the water-cement ratio of 0.3=0.64
(Note: If the 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 values are reduced by 10%
Therefore, volume of coarse aggregate = 0.64*0.9 = 0.576
Volume of fine aggregate content = 1 -0.576 = 0.424
VIII. Mix Calculations:
The mix calculation per unit volume of concrete shall be as follows:
a) Volume of Concrete = 1 m^3
b) Volume of Cement =Mass of cement X Specific gravity of cement 1000
= 466.24/3.15 x 1/1000
= 0.148 m^3
c) Volume of water
Mass of water = Specific gravity of water 1000
=140/1 * 1 / 1000
=0.14m^ 3
e) Volume of chemical admixture Specific gravity of admixture 1000
Mass of chemical admixture 1
=7.6/1.145 * 1 / 1000
=0.006m^ ^ 3
f) Volume of aggregate (FA & CA) =(a - (b + c + d + e))
=(1 - (0.148 + 0.14 + 0.006))
=0.706m^ 3
g) Mass of Coarse aggregate = fx Volume of coarse aggregate x Specific gravity of coarse aggregate X 1000
= 0.706 x 0.576 x 2.74 x 1000
= 1114.237 Kg/m^3
h) Mass of fine aggregate=fx Volume of fine aggregate x Specific gravity of fine aggregate X1000
= 0.706 x 0.424 x 2.74 x 1000
= 820.20 Kg/m^3
IX. Mix proportions for Trial Number 1:
Cement= 466.67 Kg/m^3
Water= 140 Kg/m^3
Fine aggregate= 820.20 Kg/m^3
Coarse aggregate = 1114.237 Kg/m^3
Chemical admixture = 7 Kg/m^3
Water-cement ratio = 0.3
Trial Mix Ratio= 1: 1.75 : 2.38
Construction Materials/Concrete Mix Design
X. The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required
slump on trial. The mix proportion shall be reworked for the actual water content and checked for durability requirements
XI. Two more trials having variation of 10% of water-cement ratio in Clause X shall be carried out and a graph between three
water-cement ratios 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.