Project on Concrete Mix Design for various grades of Concrete
- 1] The Concrete Mix Design for M35 grade concrete with fly ash :-
STEP1]Data collection :-
A)Grade Designation=M35
B)Type of cement= OPC 43 grade (IS 8112)
C)Type of mineral admixture= Fly ash admixture (IS 3812)-Part 1
D)Maximum nominal size of aggregate = 20 mm
E)Minimun Cement content =320 kg/m^3 (table 5 of IS 456:2000)
F)Maximun water-cement ratio =0.45 (table 5 of IS 456:2000)
G)Workability = 100 mm ( Slump value for pumpable concrete)
H)Exposure Codition= Severe for reinforced concrete
I)Method for concrete placing= pumping
J)Degree of supervision = Good
K)Type of aggregate= Crushed angular aggregates
L)Maximum cement content=450 kg/m^3
M)Chemical admixture type = Super plasticizer
STEP2] Test data for materials :-
A) Cement used =OPC 43 grade (IS 8112)
B) Specific gravity of cement = 3.15
C) Fly ash = From IS 3812-Part 1
D) Specific gravity of fly ash =2.2
E) Super plasticizer confirming from IS 9103
F) Specific gravity of coarse aggregate =2.74
G) Specific gravity of fine aggregate =2.74
H) Water absorption of coarse aggregate =0.5%
I) Water absorption of fine aggregate =1 %
J) Free surface moisture of coarse aggregate= Nil
K) Free surface moisture of Fine aggregate= Nil
L) Sieve Analysis = coarse aggregate( Confirming to table 2 Of IS-383)
M) Sieve Analysis = Fine aggregate( Confirming to grading zone II of table 4 Of IS-383)
STEP3] Target strength for mix proportioning :-
f'ck = fck + 1.65 S
f'ck = Target average compressive strength at 28 days
fck = Characteristics compressive strength at 28 days
S = Standard Deviation
From table I of IS 10260:2009, Standard Deviation, S= N/mm^2
therefore , 35+ 1.65 x5 = 43.25 N/mm^2
TARGET MEAN STRENGTH =43.25 N/mm^2
STEP4] Selection of water-cement ratio :-
The maximum water-cement ratio to design M35 grade of concrete can be found from table 5 of IS 456:2000
Maximum water-cement ratio=0.45
Based on the experience adopted water-cement ratio is 0.44
Hence, 0.44 < 0.45, OK
Adopted water-cement ratio=0.44
STEP5]Selection of water content :-
From table 2 of IS 10260:2009 , maximum water content for 20mm aggregate = 186 litre (for 25 to 50 mm slump range)
Clause 4.2 suggests increasing of 3% of water content for extra 25 mm slump from 50mm slump. so a 6% is to be added to it
Estimated water content for 100mm slump = 186 +(6/100) x 186 =197 litre
As the superplasticizer is used ,the water content can be reduced upto 20% and Above
based on trials with superplasticizer water content reduction of 20% has been achieved
hence, the arrived water content 197 X 0.8 = 158 litre
Water required = 158 litre
STEP6] Calculation of cement and fly ash required :-
A) Adopted water-cement ratio=0.44
B) Total cementitious (cement + Fly ash)requirement = Water content/water-cement ratio = 158/0.44 = 359 kg/m^3
C) The cementitious content has to be incresased in order to attain good workability and strength. The increment required on the basis of experience and research here we are increasing cementitious content by 10%
final cementitious content =359 x1.10 = 395 kg/m^3
From Table 5 of IS 456:2000, minimum content for severe exposure conditions , 320 kg/m^
395 kg/m^3 > 320 kg/m^3 hence ok.
cementitious material content = 395
New Water-Cement ratio = =158/395 =0.4
Fly ash content is taken as 30% of the total cementitious content = 395 x 0.3 =118.5 kg/m^3
Cement required = 395 - 118 =277 kg/m^3
Cement quality saved due to fly ash addition = 350 -277 = 73kg/m^3
cementitious material content, and fly ash required is 395 kg/m^3, 277 kg/m^3 and 118 kg/m^3 and the new water-cement ratio is 0.4 respectively
STEP7] Volume of coarse aggregate and fine aggregate :-
From table 3 of IS 10262:2009 volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio os 0.50 is 0.62
In the present case water-cement ratio is 0.44.Therefore,volume of coarse agregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.06. The proportion of volume of coarse is increased by 0.02 ( at the rate of -/+ 0.01 for every ± 0.05 chnage in water-cement ratio)
Therefore,correcetd proportion of volume coarse aggregate for the water-cement ratio of 0.44 is 0.632
For pumpables concrete these values should be reduced upto 10%
therfore volume of coarse aggregate = 0.632 x 0.9 =0.568
volume of fine aggregate content = 1-0.568 =0.431
volume of coarse aggregate and fine aggregate is 0.568 and 0.431
STEP8] Mix calculations:-
The mix calculations as 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] x 1/1000 = (277/3.15) x (1/1000) = 0.087m^3
C) Volume of fly ash = [ Mass of fly ash] / [Specific gravity of fly ash ] x 1/1000 = (118/2.2) x (1/1000) = 0.053 m^3
D) Volume of water = [ Mass of water] / [Specific gravity of water] x 1/1000 = (158/1) x (1/1000) = 0.158 m^3
E) Volume of of chemical admixture = [ Mass of admixture] / [Specific gravity of admixture] x1/1000=(7.6/1.145)x(1/10000) = 0.006 m^3
F) Volume of all in aggregate = [a-(b+c+d+e)] =[1-(0.087+0.053+0.158+0.006)] = 0.696 m^3
G) Mass of Coarse aggregate = f x volume of coarse aggregate x Specific gravity of fine aggregate x1000 = 0.696 x 0.568 x 2.74 x 1000 = 1077 kg/m^3
H) Mass of fine aggregate = f x volume of fine aggregate x specific gravity of fine aggregate x 1000 = 0.696 x 0.431 x 2.74 x 1000 = 822 kg/m^3
STEP 9] Mix Proportions :-
A) Cement = 277 kg/m^3
B) Fly Ash = 118 kg/m^3
C)Water = 158kg/m^3
D)Fine aggregate = 822 kg/m^3
E) Coarse Aggregate = 1077 kg/m^3
F) Chemical Admixture = 7.18 kg/m^3
Water-cement ratio= 0.4
Mix proprtion by weight = 1:2.08:2.72
STEP10] :- The slu,mp shall be measured, 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 requirments
STEP11]:- Two or more trials having variation of 10% of water-cemnt ratio shall be carried out and a graph between three water-cemnt ratios and corresponding strengths shall be plotted to wok out the mix proportions for the given target for field trials.
- 2] The Concrete Mix Design for 50 grade concrete without fly ash :-
STEP1]Data collection :-
A)Grade Designation=M50
B)Type of cement= OPC 53 grade ( Confirming to IS BIS 12269-1987)
C)Maximum nominal size of aggregate = 20 mm
D)Minimun Cement content =320 kg/m^3 (table 5 of IS 456:2000)
E)Maximun water-cement ratio =0.45 (table 5 of IS 456:2000)
F)Workability = 100 mm ( Slump value for pumpable concrete)
G)Exposure Codition= Severe for reinforced concrete
H)Method for concrete placing= pumping
I)Degree of supervision = Good
J)Type of aggregate= Crushed angular aggregates
K)Maximum cement content=450 kg/m^3
L)Chemical admixture type = Super plasticizer
STEP2] Test data for materials :-
A) Cement used =OPC 43 grade (IS 8112)
B) Specific gravity of cement = 3.15
C) Chemical admixture = Super Plasticizer conforming to IS 9103
D) Specific gravity of coarse aggregate =2.74
E) Specific gravity of fine aggregate =2.74
G) Water absorption of coarse aggregate =0.5%
H) Water absorption of fine aggregate =1 %
I) Free surface moisture of coarse aggregate= Nil
J) Free surface moisture of Fine aggregate= Nil
K) Sieve Analysis = coarse aggregate( Confirming to table 2 Of IS-383)
L) Sieve Analysis = Fine aggregate( Confirming to grading zone II of table 4 Of IS-383)
STEP3] Target strength for mix proportioning :-
f'ck = fck + 1.65 S
f'ck = Target average compressive strength at 28 days
fck = Characteristics compressive strength at 28 days
S = Standard Deviation
From table I of IS 10260:2009, Standard Deviation, S= N/mm^2
therefore , 50+ 1.65 x 5 = 58.25 N/mm^2
TARGET MEAN STRENGTH =58.25 N/mm^2
STEP4] Selection of water-cement ratio :-
The maximum water-cement ratio to design M35 grade of concrete can be found from table 5 of IS 456:2000
Maximum water-cement ratio=0.45
Based on the experience adopted water-cement ratio is 0.44
Hence, 0.44 < 0.45, OK
Adopted water-cement ratio=0.44
STEP5]Selection of water content :-
From table 2 of IS 10260:2009 , maximum water content for 20mm aggregate = 186 litre (for 25 to 50 mm slump range)
Clause 4.2 suggests increasing of 3% of water content for extra 25 mm slump from 50mm slump. so a 6% is to be added to it
Estimated water content for 100mm slump = 186 +(6/100) x 186 =197 litre
As the superplasticizer is used ,the water content can be reduced upto 20% and Above
based on trials with superplasticizer water content reduction of 20% has been achieved
hence, the arrived water content 197 X 0.8 = 158 litre
Water required = 158 litre
STEP6] Calculation of cement and fly ash required :-
A) Adopted water-cement ratio=0.44
B) Cement Content =158/0.44 =359 kg/m^3
C) From Table 5 of IS 456:2000, minimum content for severe exposure conditions , 320 kg/m^
395 kg/m^3 > 320 kg/m^3 hence ok.
Cement required is 359 kg/m^3
STEP7] Volume of coarse aggregate and fine aggregate :-
From table 3 of IS 10262:2009 volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for water-cement ratio os 0.50 is 0.62
In the present case water-cement ratio is 0.44.Therefore,volume of coarse agregate is required to be increased to decrease the fine aggregate content. As the water-cement ratio is lower by 0.06. The proportion of volume of coarse is increased by 0.02 ( at the rate of -/+ 0.01 for every ± 0.05 chnage in water-cement ratio)
Therefore,correcetd proportion of volume coarse aggregate for the water-cement ratio of 0.44 is 0.632
For pumpables concrete these values should be reduced upto 10%
therfore volume of coarse aggregate = 0.632 x 0.9 =0.568
volume of fine aggregate content = 1-0.568 =0.431
volume of coarse aggregate and fine aggregate is 0.568 and 0.431
STEP8] Mix calculations:-
The mix calculations as 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] x 1/1000 = (359/3.15) x (1/1000) = 0.114 m^3
C) Volume of water = [ Mass of water] / [Specific gravity of water] x 1/1000 = (158/1) x (1/1000) = 0.158 m^3
D) Volume of of chemical admixture = [ Mass of admixture] / [Specific gravity of admixture] x1/1000=(7.6/1.145)x(1/10000) = 0.006 m^3
E) Volume of all in aggregate = [a-(b+c+d)] =[1-(0.114+0.158+0.006)] = 0.722 m^3
F) Mass of Coarse aggregate = f x volume of coarse aggregate x Specific gravity of fine aggregate x1000 = 0.722 x 0.568 x 2.74 x 1000 = 1123 kg/m^3
G) Mass of fine aggregate = f x volume of fine aggregate x specific gravity of fine aggregate x 1000 = 0.722 x 0.431 x 2.64 x 1000 = 821 kg/m^3
STEP 9] Mix Proportions :-
A) Cement = 359 kg/m^3
B)Water = 158 kg/m^3
C)Fine aggregate = 821 kg/m^3
D) Coarse Aggregate = 1123 kg/m^3
E) Chemical Admixture = 7.18 kg/m^3
Water-cement ratio= 0.44
Mix proprtion by weight = 1:2.28:3.12
STEP10] :- The slu,mp shall be measured, 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 requirments
STEP11]:- Two or more trials having variation of 10% of water-cemnt ratio shall be carried out and a graph between three water-cemnt ratios and corresponding strengths shall be plotted to wok out the mix proportions for the given target for field trials.
RESULTS=
1] Mix proprtion by weight of M35 grade of concrete with fly ash is 1:2.08:2.72 and water-cement ratio was found to be 0.4
1] Mix proprtion by weight of M50 grade of concrete with fly ash is 1:2.28:3.12 and water-cement ratio was found to be 0.44