Project on Concrete Mix Design for various grades of Concrete
Mix design of M35 concrete with fly ash
Aim:
To calculate the Concrete Mix Design for M35 grade concrete with fly ash.
Intoduction:
Concrete mix design defines as the art of selecting suitable ingredients of concrete and determining their relative proportions with the objective of producing concrete of certain minimum strength and durability as economically as possible.
Objectives of Mix design:
- To achieve the desired workability in the plastic stage.
- To achieve the designed minimum strength in the hardened stage.
- To achieve the desired durability in the given environment conditions.
- To produce concrete as economically as possible.
Codes used:IS 10262:2009,IS 456:2000.
Materials used:
Grade designation :M35
Type of cement :OPC 43 grade conforming to IS 8112
Type of mineral admixture : Fly ash conforming to IS3812 (Part-1)
Maximum nominal size of aggregate :20mm
Minimum cement content :320 kg/m^3
Maximum water-cement ratio :0.45
Workability :75 mm (slump)
Exposure condition :Severe (for reinforced concrete)
Method of concrete placing :Pumping
Degree of supervision :Good
Type of aggregate . :Crushed angular aggregate
Maximum cement content :450 kg/m^3
Chemical admixture type :Super plastisizer
Test data for materials:
Cement used . :OPC 43 grade conforming to IS 8112
Specific gravity of cement :3.15
Specific gravity of Fly ash :2.2
Chemical admixture type :Super plastisizer conforming to IS 9103
Specific gravity of
i) Coarse aggregate :2.74
ii) Fine aggregate . :2.74
Water absorption
i) Coarse aggregate :0.5%
ii) Fine aggregate . :0.1%
Procedure:
Target mean stenght of mix proportion:
f'ck =fck + 1.65 s
f'ck = target average compressive strength at 28 days,
fck = characteristic compressive strength at 28 days.
s = standard deviation.
From IS 10262:2009 Table I, standard deviation, s =5 N/mm2.
Therefore, target strength =35 + 1.65 x 5 =43.25 N/mm2.
WATER-CEMENT RATIO:
From IS 456:2000 Table 5 , maximum water-cement ratio = 0.45.
Based on experience, adopt water-cement ratio as 0.4.
0.4 < 0.45 , hence O.K.
WATER CONTENT:
From IS 10262:2009 Table 2, maximum water content =186 litre (for 25 to 50 mm slump range)for 20 mm aggregate
Estimated water content for 75 mm slump =186+186*0.03
=192 litre.
As superplasticizer is used, the water content can be reduced by 30 percent .
Hence, the arrived water content =192 x 0.70 =134 litre.
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 = 320 kg/m3
335 kg/m3 > 320 kg/m3, hence, O.K.
If the fly ash is used in the cement 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 it's weight=369*0.3
=111 Kg/m^3.
Cement used =369*0.7
=258 Kg/m^3.
VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT:
From IS 10262:2009 Table 3. volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone I) for
water-cement ratio of 0.50 =0.60.
In the present case water-cement ratio is 0.40. So the volume of coarse aggregate is required to be increased 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 proportion of volume of coarse aggregate for the water-cement ratio of 0.40 = 0.62.
For pumpable concrete these values should be reduced by 10 percent.
Therefore, volume of coarse aggregate = 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).
. =(258/3.15)*(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 plastiscizer)*(1/1000)
(super plasticizer) ( 2.0 percent =(7.38/2.1)*(1/1000)
by mass of cementitious material) =0.003 m^3
f) Volume of aggregate =[a-(b+c+d+e)]
=[Volume of concrete-(Volume of cement +Volume of Fly ash +Volume of water+Volume of chemical admixture)].
=[1-(0.082+0.05+0.134+0.003)]
=1-0.266
=0.731 m^3
g) Mass of coarse aggregate =Volume of all 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 gravity of fine aggregate*1000.
=0.731*0.44*2.74*1000
=881 kg.
Results:
MIX RATIO FOR M35 CONCRETE:
Cement :258 Kg/m^3
Fly ash :111 Kg/m^3
Water :134 lit.
Chemical ad-mixture :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.
Mix design of M50 concrete
Aim:
To calculate the Concrete Mix Design for M50 grade concrete without fly ash.
Intoduction:
Concrete mix design defines as the art of selecting suitable ingredients of concrete and determining their relative proportions with the objective of producing concrete of certain minimum strength and durability as economically as possible.
Objectives of Mix design:
- To achieve the desired workability in the plastic stage.
- To achieve the designed minimum strength in the hardened stage.
- To achieve the desired durability in the given environment conditions.
- To produce concrete as economically as possible.
Codes used:IS 10262:2009,IS 456:2000.
Materials used:
Grade designation :M50
Type of cement :OPC 43 grade conforming to IS 8112
Maximum nominal size of aggregate :20mm
Minimum cement content :360 kg/m^3
Maximum water-cement ratio :0.4
Workability :100 mm (slump)
Exposure condition :Extreme (for reinforced concrete)
Method of concrete placing :Pumping
Degree ofsupervision :Good
Type of aggregate :Crushed angular aggregate
Maximum cement content :450 kg/m^3
Chemical admixture type :Super plastisizer
Test data for materials:
Cement used :OPC 43 grade conforming to IS 8112
Specific gravity of cement :3.15
Chemical admixture type :Super plastisizer conforming to IS 9103
Specific gravity of
i) Coarse aggregate :2.74
ii) Fine aggregate :2.74
Water absorption
i) Coarse aggregate :0.5%
ii) Fine aggregate :0.1%
Procedure:
Target mean strenght of mix proportion:
f'ck =fck + 1.65 s
f'ck = target average compressive strength at 28 days,
fck = characteristic compressive strength at 28 days.
s = standard deviation.
From IS 10262:2009 Table I, standard deviation, s =5 N/mm2.
Therefore, target strength =50 + 1.65 x 5 =58.25 N/mm2.
WATER-CEMENT RATIO:
From IS 456:2000 Table 5 , maximum water-cement ratio = 0.4.
Based on experience, adopt water-cement ratio as 0.35.
0.35 < 0.4 , hence O.K.
WATER CONTENT:
From IS 10262:2009 Table 2, maximum water content =186 litre (for 25 to 50 mm slump range)for 20 mm aggregate
Estimated water content for 100 mm slump =186+186*0.06
. =197 litre.
As superplasticizer is used, the water content can be reduced up to 30 percent.
Hence, the arrived water content =197 x 0.70 =138 litre.
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 'Extreme' exposure condition = 360 kg/m3
394 kg/m3 > 360 kg/m3, hence, O.K.
VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE CONTENT:
From IS 10262:2009 Table 3. volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone I) for
water-cement ratio of 0.50 =0.60.
In the present case water-cement ratio is 0.35 so the volume of coarse aggregate is required to be increased 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 proportion of volume of coarse aggregate for the water-cement ratio of 0.35 = 0.63.
For pumpable concrete these values should be reduced by 10 percent.
Therefore, volume of coarse aggregate = 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 ofcement)*(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 plastiscizer)*(1/1000)
(super plasticizer) (2.0 percent =(7.88/2.1)*(1/1000)
by mass of cementitious material) =0.0037 m^3
e) Volume of aggregate =[a-(b+c+d)]
=[Volume of concrete-(Volume of cement +Volume of chemical admixture +Volume of water)].
=[1-(0.125+0.0037+0.138)]
=1-0.267
=0.733 m^3
f) Mass of coarse aggregate =Volume of all 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 gravity of fine aggregate*1000.
=0.733*0.433*2.74*1000
=869 kg.
Results:
MIX RATIO FOR M50 CONCRETE:
Cement :394 Kg/m^3
Chemical admixture :7.8 Kg/m^3
Water :138 lit.
Fine aggregate . :869 Kg/m^3
Coarse aggregate :1138 Kg/m^3
Water-cement ratio :0.35
Mix proportion for M50 grade= 1:2.20:2.88.