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Tuesday, 14 December 2021
M30 Grade Concrete Mix Design with Fly Ash – IS10262
M30 Grade Concrete Mix Design with Fly Ash – IS10262
This article covers the mix design calculation of M30 Grade Concrete with Fly ash admixture and Poly Carboxylite superplasticizer as per IS10262-2009. Superplasticizers are required for all high-strength concrete to get good workability and strength in concrete.
I. STIPULATIONS FOR PROPORTIONING OF M30 GRADE CONCRETE
Minimum cement content is chosen based on the grade of concrete. Water content is chosen based on the size of the aggregate and exposure.
A
Grade Designation
M30
B
Type of Cement
OPC 53
C
Type of Admixture
Fly Ash
D
Maximum Nominal Size of Aggregate
20mm
E
Minimum Cement Content
320kg
Table 5-IS456 As per code
F
Maximum Cement Content
450kg
As per code
G
Partial replacement of cement by Fly Ash
30%
as per requirement
H
Maximum W/C ratio
0.45
Table 5-IS456 As per code
I
Workability
50mm
as per requirement
J
Chemical Admixture
Polycarboxylate Superplasticizers
as per requirement
II. TEST DATA FOR MATERIALS
Materials have to be tested to check their quality and to find their different physical and chemical properties.
A
Cement Used
OPC 53
Confirming to IS8112
B
Specific Gravity of Cement
3.15
Test – IS: 2720
C
Mineral Admixture
Fly Ash
Confirming to IS12089
D
Specific Gravity of Fly Ash
2.90
E
Chemical Admixture
@0.6%
IS9103
F
Specific Gravityof
Test – IS 2386
Coarse Aggregate
2.74
Fine Aggregate
2.74
Admixture PCE based
1.12
G
Water Absorption
Test – IS 2386
Coarse aggregate
0.5 %
Fine aggregate
1 %
H
Sieve Analysis
Test – IS 2386
Coarse aggregate
Confirming to Table 2-IS383
Fine aggregate
Zone II
Confirming to Table 4-IS383
III. TARGET STRENGTH FOR MIX PROPORTIONS OF M30 GRADE CONCRETE
The target strength (Fck) of the concrete should be higher than the required strength of the concrete (fck) because of variations in the quality of ingredients, mixing method, and other factors that are not considered in the Mix Design. The value of Standard deviation (S) for different grades of concrete is given in Table 1 of IS456.
Fck
= fck+1.65s
“S” from Table1-IS10262
Fck
= 30+(1.65 x 5)
Fck
= 38.25 N/mm2
IV. SELECTION OF WATER-CEMENT RATIO
The maximum water-cement ratio for different grades of concrete is given in Table 5-IS456. The Water-cement ratio directly affects the strength of the concrete hence change in the water-cement ratio should be based on experience and research.
Maximum W/C ratio
=0.45
Table 5-IS456
Adopted W/C ratio
=0.45
V. SELECTION OF WATER CONTENT
Maximum Water Content
=186 L
Table 2-IS1026 for 25 to 50mm slump range
With the help of Since superplasticizers water content can be reduced to reduce the void ratio in concrete and increase the density of concrete. The percentage of reduction of water content depends on the type of superplasticizer.
Percentage of Reduction in water content
=15%
Water content requirement after SP
=186 – (0.15*186)
=158.1
Adopted Water Content
=160 L
VI. CALCULATION OF CEMENT AND FLY ASH CONTENT
Adopted Water Cement Ratio
=0.45
Total Cementitious (Cement +Flyash) requirement
= Water Content / WaterCement ratio
=160/0.45
=355.55 kg
Since we are using fly ash Cementitious content (Cement+Fly ash) should be increased. Here we have increased the cementitious content by 10 % based on research and experience.
Final Cementitious Content (Cement+ Fly ash )
= 356+(356*0.10)
=391.6 kg
Minimum Cement Content required for ‘severe’ exposure
=320kg
Table 5-IS456
Adopted Cementious content
=391.6 kg
> 320kg
Fly ash content requirement
= 391.6 * 0.30
30% replacement
= 117.48 ~ 118 kg
Cement Content requirement
=Cementious content – Fly ash
=391.6-117.48
= 274.12 ~ 274 kg
Calculation of Super Plasticiers @ 0.6 percent to the mass of cementitious content = 391.6*(0.6/100) = 2.35 kg
VII COARSE AND FINE AGGREGATE
The standard coarse aggregate ratio is given in table 3 but it should be adjusted based on the water-cement ratio based on experience.
Coarse Aggregate ratio
=0.62
Table3-IS10262 (For W/C =0.5)
Coarse Aggregate ratio for 0.45 w/c ratio
=0.63
Final Fine Aggregate ratio
=0.37
(1-0.63) = 0.37
VIII MIX CALCULATIONS OF M30 GRADE CONCRETE
A
Volume of Concrete
= 1 cu.m
B
Volume of Cement
= Cement weight/(S.G*1000)
= 274/(3.15*1000)
= 0.086 cu.m
C
Total Volume of Fly ash
= Fly ash weight /(S.G*1000)
= 118/(2.9*1000)
= 0.041 cu.m
D
Volume of Water
= Water /(S.G*1000)
= 160/(1*1000)
= 0.160 cu.m
E
Volume of Superplasticizers
= S.P/(S.G*1000)
= 2.35/(1.12*1000)
= 0.002 cu.m
F
Total Aggregates requirement
= A – (B+C+D+E)
= 1 -(0.086 +0.041+0.160+0.002)
=0.71 cu.m
G
Coarse Aggregate (C.A)
= F * C.A ratio * S.G * 1000
= 0.71*0.63 *2.74 *1000
= 1225 kg
I
Fine Aggregate (F.A)
= F * F.A ratio * S.G * 1000
= 720 kg
Cement Fly ash Sand Aggregate Water and Superplasticizer needed for M30 grade concrete
S.No.
MATERIALS
QUANTITY
1
Cement
274 kg
2
Flyash
118 kg
3
Fine Aggregate
720 kg
4
Coarse Aggregate (20mm)
1225 kg
5
WATER
160 L
6
SuperPlasticizer
2 L
Mix Ratio of M30 Grade concrete by weight with fly ash admixture is Cement : Flyash: F.A: C.A : Water = 1: 0.43 : 2.6 : 4.47: 0.58
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