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.

AGrade DesignationM30
BType of CementOPC 53
CType of AdmixtureFly Ash
DMaximum Nominal
Size of Aggregate
20mm
EMinimum Cement Content320kgTable 5-IS456
As per code
FMaximum Cement Content450kgAs per code
GPartial replacement
of cement by Fly Ash
30%as per requirement
HMaximum W/C ratio0.45Table 5-IS456
As per code
IWorkability50mmas per requirement
JChemical AdmixturePolycarboxylate
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.

ACement UsedOPC 53Confirming to
IS8112
BSpecific Gravity of Cement3.15Test – IS: 2720 
CMineral AdmixtureFly AshConfirming to IS12089
DSpecific Gravity of Fly Ash2.90
EChemical Admixture@0.6%IS9103 
FSpecific Gravity ofTest – IS 2386
Coarse Aggregate2.74
Fine Aggregate2.74
Admixture PCE based1.12
GWater AbsorptionTest – IS 2386
Coarse aggregate0.5 %
Fine aggregate 1 %
HSieve AnalysisTest – IS 2386
Coarse aggregateConfirming to
Table 2-IS383
Fine aggregate Zone IIConfirming 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=0.45Table 5-IS456
Adopted W/C ratio=0.45

V. SELECTION OF WATER CONTENT

Maximum Water Content=186 LTable 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
=320kgTable 5-IS456
Adopted Cementious content=391.6 kg> 320kg
Fly ash content requirement= 391.6 * 0.3030% 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=0.62Table3-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

AVolume of Concrete= 1 cu.m
BVolume of Cement= Cement weight/(S.G*1000)
= 274/(3.15*1000)
= 0.086 cu.m
CTotal Volume of Fly ash= Fly ash weight /(S.G*1000)
= 118/(2.9*1000)
= 0.041 cu.m
DVolume of Water= Water /(S.G*1000)
= 160/(1*1000)
= 0.160 cu.m
EVolume of Superplasticizers= S.P/(S.G*1000)
= 2.35/(1.12*1000)
= 0.002 cu.m
FTotal Aggregates requirement= A – (B+C+D+E)
= 1 -(0.086 +0.041+0.160+0.002)
=0.71 cu.m
GCoarse Aggregate (C.A)= F * C.A ratio * S.G * 1000
= 0.71*0.63 *2.74 *1000
= 1225 kg
IFine 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.MATERIALSQUANTITY
1Cement274 kg
2Flyash118 kg
3Fine Aggregate720 kg
4Coarse Aggregate (20mm)1225 kg
5WATER160 L
6SuperPlasticizer2 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


Er. SP.ASWINPALANIAPPAN., M.E.,(Strut/.,)
Structural Engineer
http://ganeshadesigningstudio.in/

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