Project on Concrete Mix Design for various grades of Concrete
Aim: To calculate the Concrete Mix Design for M35 grade concrete with fly ash
Introduction:Concrete mix design defines as the art of selecting suitable ingredients of cocnrete and determining their relative proportions with the objective of prosucing concrete of certain minimum strength and durability as economically as possible.
Obejctive of Mix design:
- To achieve the designed desired workability in the plastic stage.
- To achieve the desired durability in the given environmental condition.
- To achieve the designed minimum strength in the hardened stage.
Code: IS 10262-2009, IS 456-2000,
Material used:
1.Grade designation : M35
2.Type of cement : OPC 43 grade confirming to IS 8112
3.Type of mineral admixture : Fly ash conforming to IS 3812(part-1)
4.Maximum nominal size of aggregates : 20mm
5.Minimum cement content : 320kg/m^3
6.Maximum water cement ratio : 0.45
7.Workability : 75mm (slump)
8.Exposure condition : Severe (for reinforced concrete)
9.Method of concrete placing : Pumping
10.Degree of supervision : Good
11.Type of aggregate : Crushed angular aggregates
12.Maximum cement content : 450Kg/m^3
13.Chemical admixture type : Super plastisizer
Test data for materials;
Cement used : OPC 43 grade confirming to IS 8112
Specific gravity of cement : 3.15
Specific gravity of Fly ash : 2.2
Chemical admixture type : Super plastisizer confirming to IS 9103
Specific gravity of
- Coarse aggregate : 2.74
- Fine aggregate : 2.74
Water absorption
- Coarse aggregate : 0.5%
- Fine aggregate : 0.1%
Free (surface) moisture
- Coarse aggregate : Nil
- Fine aggregate : Nil
Procedure:
TARGET MEAN STRENGTH FOR MIX PROPORTIONING:
f'ck = fck + 1.65 s
Where,
f'ck = Target average compressive strength at 28 days.
fck = Charactreistic compressive strength at 28 days.
s = Standard deviation.
From IS 10262-2009 Table 1, standard deviation, s = 5 N/mm^2.
Therefore target strength = 35 + 1.65 * 5 = 43.25 N/mm^2.
SELECTION OF WATER CEMENT RATIO:
From IS 456-2000 Table-5 , maximum water cement ratio=0.45.
Based on experience, adpot water cement ratio as 0.4.
0.4 < 0.45, hence OK.
SELECTION OF WATER CONTENT:
From IS 10262:2009 Table 2, maximum water content = 186 litres ( for 25 to 50mm slump)For 20 mm aggregates.
Estimated water content for 75 mm slump = 186 =186x0.03
=192 litre.
As superplasticizer is used the water content can be reduced up 20% and above.
Based on trails with superplasticizer water content reduction of 30% has been achieved.
Hence, the arrived water content = 192*0.70 = 134 litre.
CALCULATION OF CEMENT CONTENT:
Water cement ratio = 0.4
Cement content = 134/0.4
= 335 kg/m^3.
From IS 456-2000 Table 5, The minimum cement content for 'Severe' exposure condition = 320Kg/m^3.
335 kg/m^3 > 320 kg/m^3, hence OK.
If the fly ash is used in the cement by trail and experiment method increase the cement content by 10% as the fly ash is used.
=335 * 1.1
= 369 kg/m^3.
Water cement ratio = 134/369
= 0.363
Fly ash in the cement is 30% by its weight = 369 * 0.3
= 111kg/m^3.
Cement used = 369 * 0.7
= 258 kg/m^3.
PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT:
From IS 10262-2009 Table 3, Volume of coarse aggregate corresponding to 20mm size aggregates and fine aggregates (Zone1) for,
Water cement ratio of 0.50 = 0.60.
In the present case water cement ratio is 0.40. Therefore the volume of coarse aggregate is required to be incresed to decrease the fine aggregate content.
As the water cement ratio is lower by 0.10. 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).
Therefore corrected proportio 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 suitably, based on experience.
For pumpable concrete these values should be reduced by 10%.
Therefore, volume of coarse aggregates = 0.62 x 0.9 = 0.56.
Volume of fine aggregate content = 1-0.56 = 0.44.
MIX CALCULATIONS:
The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete = 1 m^3
b) Volume of cement = (Mass of cement/ Specific gravity of cement)*(1/1000)
= 0.082 m^3.
c) Volume of water = (Mass of water/ Specific gravity of water)*(1/1000)
= (134/1)*(1/1000)
= 0.134 m^3.
d) Volume of fly ash = (Mass of Fly ash/ Specific gravity of fly ash)*(1/1000)
= (111/2.2)*(1/1000)
= 0.050 m^3.
e) Volume of chemical admixture = (Mass of super plasticizer/ Specific gravity of Super plasticizer)*(1/1000)
(Superplasticizer) (@2.0 percent)= (7.38/2.1)*(1/1000)
=0.003 m^3.
f) volume of aggregate = (Volume of concrete -(Volume of cement + Volume of fly ash+ Volume of water + Volume of chemical admixture)
= [1-(0.082+0.05+0.134+0.03)]
= 1- 0.266
= 0.731 m^3.
g) Mass of coarse aggregate = (Volume of all in aggregate*volume of coarse aggregate*Specific gravity of coarse aggregate*1000
= 0.731*0.56*2.74*1000
= 1121 Kg.
h) Mass of fine aggregate = (Volume of aggregate * Volume of fine aggregate* Specific garvity of fine aggregates*1000)
= 0.731*0.44*2.74*1000
= 881 kg.
Results:
MIX PROPORTIONS FOR M35 GRADE CONCRETE:
Cement = 258 kg/m^3
Fly ash = 111 kg/m^3
Water = 134 litre
Chemical admixture = 7.38 kg/m^3
Fine aggregate = 881 kg/m^3
Coarse aggregate = 1121 kg/m^3
Water cement ratio = 0.363
Mix Proportion for M35 grade = 1 : 2.38 : 3.03.
Aim: To calculate the Concrete Mix Design for M50 grade concrete without fly ash
Introduction:Concrete mix design defines as the art of selecting suitable ingredients of cocnrete and determining their relative proportions with the objective of prosucing concrete of certain minimum strength and durability as economically as possible.
Obejctive of Mix design:
- To achieve the designed desired workability in the plastic stage.
- To achieve the desired durability in the given environmental condition.
- To achieve the designed minimum strength in the hardened stage.
Code: IS 10262-2009, IS 456-2000,
Material used:
1.Grade designation : M50
2.Type of cement : OPC 43 grade confirming to IS 8112
3.Maximum nominal size of aggregates : 20mm
4.Minimum cement content : 360kg/m^3
5.Maximum water cement ratio : 0.45
6.Workability : 100mm (slump)
7.Exposure condition : Severe (for reinforced concrete)
8.Method of concrete placing : Pumping
9.Degree of supervision : Good
10.Type of aggregate : Crushed angular aggregates
11.Maximum cement content : 450Kg/m^3
12.Chemical admixture type : Super plastisizer
Test data for materials;
Cement used : OPC 43 grade confirming to IS 8112
Specific gravity of cement : 3.15
Chemical admixture type : Super plastisizer confirming to IS 9103
Specific gravity of
- Coarse aggregate : 2.74
- Fine aggregate : 2.74
Water absorption
- Coarse aggregate : 0.5%
- Fine aggregate : 0.1%
Free (surface) moisture
- Coarse aggregate : Nil
- Fine aggregate : Nil
Procedure:
TARGET MEAN STRENGTH FOR MIX PROPORTIONING:
f'ck = fck + 1.65 s
Where,
f'ck = Target average compressive strength at 28 days.
fck = Charactreistic compressive strength at 28 days.
s = Standard deviation.
From IS 10262-2009 Table 1, standard deviation, s = 5 N/mm^2.
Therefore target strength = 50 + 1.65 * 5 = 58.25 N/mm^2.
SELECTION OF WATER CEMENT RATIO:
From IS 456-2000 Table-5 , maximum water cement ratio=0.40.
Based on experience, adpot water cement ratio as 0.35.
0.35 < 0.40, hence OK.
SELECTION OF WATER CONTENT:
From IS 10262:2009 Table 2, maximum water content = 186 litres ( for 25 to 50mm slump)For 20 mm aggregates.
Estimated water content for 75 mm slump = 186 =186x0.03
=197 litre.
As superplasticizer is used the water content can be reduced up 20% and above.
Based on trails with superplasticizer water content reduction of 30% has been achieved.
Hence, the arrived water content = 197*0.70 = 138 litre.
CALCULATION OF CEMENT CONTENT:
Water cement ratio = 0.35
Cement content = 138/0.35
= 394 kg/m^3.
From IS 456-2000 Table 5, The minimum cement content for 'Severe' exposure condition = 360Kg/m^3.
394 kg/m^3 > 360 kg/m^3, hence OK.
PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT:
From IS 10262-2009 Table 3, Volume of coarse aggregate corresponding to 20mm size aggregates and fine aggregates (Zone1) for,
Water cement ratio of 0.50 = 0.60.
In the present case water cement ratio is 0.35. Therefore the volume of coarse aggregate is required to be incresed to decrease the fine aggregate content.
As the water cement ratio is lower by 0.15. The proportion of volume of coarse aggregate is increased by 0.03 ( at the rate of +/- 0.01 for every + 0.05 change in water cement ratio).
Therefore corrected proportio of volume of coarse aggregate for the water cement ratio of 0.35 = 0.63.
NOTE: In case the coarse aggregate is not angular one, then also volume of coarse suitably, based on experience.
For pumpable concrete these values should be reduced by 10%.
Therefore, volume of coarse aggregates = 0.63 x 0.9 = 0.567.
Volume of fine aggregate content = 1-0.567 = 0.433.
MIX CALCULATIONS:
The mix calculations per unit volume of concrete shall be as follows:
a) Volume of concrete = 1 m^3
b) Volume of cement = (Mass of cement/ Specific gravity of cement)*(1/1000)
= (394/3.15)*(1/1000).
= 0.125 m^3.
c) Volume of water = (Mass of water/ Specific gravity of water)*(1/1000)
= (138/1)*(1/1000)
= 0.138 m^3.
d) Volume of chemical admixture = (Mass of super plasticizer/ Specific gravity of Super plasticizer)*(1/1000)
(Superplasticizer) (@2.0 percent)= (7.88/2.1)*(1/1000)
=0.0037 m^3.
e) volume of aggregate = (Volume of concrete -(Volume of cement + Volume of fly ash+ Volume of water + Volume of chemical admixture)
= [1-(0.125+0.0037+0.138)]
= 1- 0.267
= 0.733 m^3.
f) Mass of coarse aggregate = (Volume of all in aggregate*volume of coarse aggregate*Specific gravity of coarse aggregate*1000
= 0.733*0.567*2.74*1000
= 1138 Kg.
g) Mass of fine aggregate = (Volume of aggregate * Volume of fine aggregate* Specific garvity of fine aggregates*1000)
= 0.733*0.433*2.74*1000
= 869 kg.
Results:
MIX PROPORTIONS FOR M35 GRADE CONCRETE:
Cement = 394 kg/m^3
Water = 138 litre
Chemical admixture = 7.8 kg/m^3
Fine aggregate = 869 kg/m^3
Coarse aggregate = 1138 kg/m^3
Water cement ratio = 0.35
Mix Proportion for M35 grade = 1 : 2.20 : 2.88.