Project on Concrete Mix Design for various grades of Concrete

Calculate the Concrete Mix Design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash

AIM:

To Calculate Mix Design for M35 grade concrete with fly ash.

INTRODUCTION:

Mix design calculation for M35 grade concrete with fly ash. The procedure is same when fly ash is used, the only change will be the specific gravity of the admixture. The specific gravity of fly ash ranges from 2.1 to 3 and Superplasticizers are required for all high strength concrete to get good workability and good strength in concrete.

PROCEDURE IN DETAIL:

STEP 1:

STIPULATIONS FOR PROPORTIONING OF M35 GRADE CONCRETE:

This section deals with the conditions and requirements of the concrete to be made.

A	Grade Designation	M35
B	Type of Cement (Confirming to IS8112)	OPC 53
C	Type of Mineral Admixture (Conforming to IS3812-Part 1)	Fly Ash
D	Minimum Nominal Size of Aggregate	20mm
E	Minimum Cement Content (Table 5- IS 456)	340kg
F	Maximum Cement Content (As per code)	450kg
G	Partial Replacement of Cement by Fly Ash ( As per requirement - Acc to code IS 456-2000, Replacement of OPC by 35% of fly ash as binding material is permitted).	30%
H	Maximum W/C ratio (Table 5-IS 456)	0.45
I	Workability (Slump for Pumpable Concrete)	100mm
J	Chemical Admixture (Conforming to IS 9103)	Superplasticizer
K	Exposure Condition (For Reinforced Concrete)	Severe
L	Method of Concrete Placing	Pumping

 

 

 

 

 

 

 

 

 

 

 

 

STEP 2:

TEST DATA FOR MATERIALS:

Materials should be tested in the laboratory as per tests given in the code book and their properties should be found. The values for the material properties will be used in the design process and to check the quality of the material with  the help of codebook standards. Standard values are taken here for calculation purposes.

A	Cement Used	OPC 53
B	Specifc Gravity of Cement	3.15
C	Mineral Admixture	Fly Ash
D	Specific Gravity of Mineral Admixture	2.90
E	Chemical Admixture	Superplasticizer
F	Specific Gravity of Coarse Aggregate (IS 2386)	2.74
G	Specific Gravity of Fine Aggregate (IS 2386)	2.74
H	Specific Gravity of Chemical Admixture (IS 2386)	1.145
I	Water Absorption of Coarse Aggregate (IS 2386)	0.5%
J	Water Absorption of Fine Aggregate (IS 2386)	1%
K	Sieve Analysis for Coarse Aggregate	Table 2-IS383
L	Sieve Analysis for Fine Aggregate (Zone II)	Table 4-IS383

 

 

 

 

 

 

 

 

 

 

 

STEP 3:

TARGET STRENGTH FOR MIX PROPORTIONS OF M35 GRADE CONCRETE:

The strength of the concrete may deviate slightly depends on the quality of the material, method of mixing and construction practices. Hence target strength (Fck). The value of standard deviation (s) for different grades of concrete is given in Table 1 of IS 456.

Fck = fck+(1.65*s) ; "S" from Table 1-IS 10262

Fck = 35+1.65*5

Fck = 43.25 N/mm^2.

 

STEP 4:

SELECTION OF WATER-CEMENT RATIO:

The maximum water-cement ratio for different grades of concrete is given in Table 5 - IS 456. Here, we can reduce the water-cement based on the requiremet. The water-cement ratio directly affects the strength of the concrete.

Maximum water-cemet ratio = 0.45 ; Table 5 - IS 456

Adopted W/C ratio = 0.45.

 

STEP 5:

SELECTION OF WATER CONTENT:

Maximum Water Content = 186 Litres ; Table 2 - IS 10262

Above water-cement is for 25 to 50mm slump but the slump we require is 100mm. Hence, We need to increase the water content to get the required slump for good workability. Clause 4.2 of IS 10262 suggests an increase of 3% of water content from its orginal value for every increase of 25mm. Here we have a 50mm increase in the water content hence we have to increase the water content by 6%.

Water-Content for 100mm Slump = 186+(0.06*186)

Water-Content for 100mm Slump = 197.16 Litre = 198 Litre.

Since Superplasticizers are used water content can be reduced to get good strength of concrete. The percentage of reduction of water depends on the type of superplasticizers used in the concrete. As superplasticizer is used, the water content can be reduced up to 30%.

Based on the trails water content reduction of 29% is achieved with plasticizer.

Hence, The Percentage of reduction in water content = 20%

Water Content required after Super Plasticizer is added = 198 - (0.20*198)

                                                                                = 160 Litre.

 

STEP 6:

CALCULATION OF CEMENT AND FLY ASH CONTENT:

Adopted W/C ratio = 0.45.

Total Cementitious  (Cement + Fly Ash) requirement = Water Content / Water-Cement ratio

                                                                            = 160 / 0.45

                                                                            = 355.55 kg = 356 kg.

Since Fly Ash is used the amount of cementitious content (Cement+Fly Ash) shall be increased to get good workability and strength. The percentage of increase depending on the experience and research. Here we increased the cementitious content by 1.1%.

Final Cementitious Content (Cement+Fly Ash) = 356*1.1

                                                                   =   391.6 kg

Minimum Cement Content required for 'Severe' Exposure Condition = 340 kg ; Table 5-IS 456.

Adopted Cementious Content = 391.6 kg > 340 kg.

Fly Ash Content requirement = 391.6*0.30 ; Since 30% of fly ash is replacement.

                                          = 117.48 kg = 118 kg.

Cement Content Requirement = Cementious Content - Fly Ash

                                           = 391.6-117.48 = 274.12 kg = 275 kg.

 

STEP 7:

COARSE AND FINE AGGREGATE:

Coarse Aggregate ratio = 0.62 ; Table 3 - IS 10262 (For W/C=0.5).

Coarse Aggregate ratio for 0.45 W/C ratio = 0.63 ( Adding 0.01 for every decrease 0.05 and vice cersa).

For pumpable concrete these values are reduced by 10%

Therefore, The Volume of Coarse Aggregate = 0.63 * 0.9 = 0.567

Final Fine Aggregate ratio = 0.433 ; (1-0.57 = 0.433).

 

STEP 8:

MIX CALCULATIONS OF M35 GRADE CONCRETE:

A	Volume of Concrete	= 1 cu.m
B	Total Volume of Cement	= Mass of Cement / (S.G * 1000)
		= 275 / (3.15*1000)
		= 0.087 cu.m
C	Total Volume of Fly Ash	= Mass of Fly Ash / (S.G*1000)
		= 118 / (2.5*1000)
		= 0.041 cu.m
D	Volume of Water	= Mass of Water / (S.G * 1000)
		= 160 / (1*1000)
		= 0.160 cu.m
E	Volume of Superplasticizers	= Mass of Superplasticizers / (S.G * 1000)
		= 7.6 / (1.145 * 1000)
		= 0.006 cu.m
F	Total Aggregate Requirement	= A-(B+C+D+E)
		= 1-(0.087+0.041+0.160+0.006)
		= 0.706 cu.m = 0.71 cu.m
G	Mass of Coarse Aggregate	= F * C.A ratio * S.G * 1000
		= 0.71 * 0.567* 2.74 * 1000
		= 1103.04 kg
H	Mass of Fine Aggregate	= F * F.A * ratio * S.G * 1000
		= 0.71 * 0.433 * 2.74 * 1000
		= 842.35 kg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RESULT:

Cement, Fly Ash, Fine Aggregate, Coarse Aggregate, Water and Superplasticizer needed for M35 grade of concrete.

S.No	MATERIALS	QUANTITY
1	Cement	275 kg/m^3
2	Fly Ash	118 kg/m^3
3	Fine Aggregate	842 kg/m^3
4	Coarse Aggregate (20mm)	1103 kg/m^3
5	Water	160 kg/m^3
6	Chemical Admixture	7 kg/m^3
7	Water-Cement Ratio	0.45

 

 

 

 

 

 

 

 

 

 

To find the design mix ratio divide the calculated value all material by weight of cement.

Therefore Mix Ratio of M35 grade Concrete by weight is Cement : Fly Ash : F.A : C.A : Water = 1 : 0.42 : 3.06 : 4.01 : 0.58.

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Calculate the Concrete Mix Design for M50 grade concrete without Fly ashAIM:

To Calculate Mix Design for M50 grade concrete without fly ash.

INTRODUCTION:

M50 is generally used in high rise towers above 40 floors, and instead of slump cone test we have to check flow index of concrete above M50. 

PROCEDURE IN DETAIL:

STEP 1:

STIPULATIONS FOR PROPORTIONING OF M35 GRADE CONCRETE:

This section deals with the conditions and requirements of the concrete to be made.

A	Grade Designation	M50
B	Type of Cement (Confirming to IS8112)	OPC 53
C	Minimum Nominal Size of Aggregate	20mm
D	Minimum Cement Content (Table 5- IS 456)	360kg
E	Maximum Cement Content (As per code)	450kg
F	Maximum W/C ratio (Table 5-IS 456)	0.35
G	Workability (Slump for Pumpable Concrete)	100mm
H	Chemical Admixture (Conforming to IS 9103)	Superplasticizer
I	Exposure Condition (For Reinforced Concrete)	Extreme
J	Degree of Supervision	Good
K	Method of Concrete Placing	Pumping

 

 

 

 

 

 

 

 

 

 

 

STEP 2:

TEST DATA FOR MATERIALS:

Materials should be tested in the laboratory as per tests given in the code book and their properties should be found. The values for the material properties will be used in the design process and to check the quality of the material with  the help of codebook standards. Standard values are taken here for calculation purposes.

A	Cement Used	OPC 53
B	Specifc Gravity of Cement	3.15
C	Chemical Admixture	Superplasticizer
D	Specific Gravity of Coarse Aggregate (IS 2386)	2.74
E	Specific Gravity of Fine Aggregate (IS 2386)	2.74
F	Specific Gravity of Chemical Admixture (IS 2386)	1.145
G	Water Absorption of Coarse Aggregate (IS 2386)	0.5%
H	Water Absorption of Fine Aggregate (IS 2386)	1%
I	Sieve Analysis for Coarse Aggregate	Table 2-IS383
J	Sieve Analysis for Fine Aggregate (Zone II)	Table 4-IS383

 

 

 

 

 

 

 

 

 

STEP 3:

TARGET STRENGTH FOR MIX PROPORTIONS OF M50 GRADE CONCRETE:

The strength of the concrete may deviate slightly depends on the quality of the material, method of mixing and construction practices. Hence target strength (Fck). The value of standard deviation (s) for different grades of concrete is given in Table 1 of IS 456.

Fck = fck+(1.65*s) ; "S" from Table 1-IS 10262

Fck = 50 +1.65*5

Fck = 58.25 N/mm^2.

 

STEP 4:

SELECTION OF WATER-CEMENT RATIO:

The maximum water-cement ratio for different grades of concrete is given in Table 5 - IS 456. Here, we can reduce the water-cement based on the requiremet. The water-cement ratio directly affects the strength of the concrete.

Maximum water-cemet ratio = 0.45 ; Table 5 - IS 456

Adopted W/C ratio = 0.35.

 

STEP 5:

SELECTION OF WATER CONTENT:

Maximum Water Content = 186 Litres ; Table 2 - IS 10262

Above water-cement is for 25 to 50mm slump but the slump we require is 100mm. Hence, We need to increase the water content to get the required slump for good workability. Clause 4.2 of IS 10262 suggests an increase of 3% of water content from its orginal value for every increase of 25mm. Here we have a 50mm increase in the water content hence we have to increase the water content by 6%.

Water-Content for 100mm Slump = 186+(0.06*186)

Water-Content for 100mm Slump = 197.16 Litre = 197 Litre.

Since Superplasticizers are used water content can be reduced to get good strength of concrete. The percentage of reduction of water depends on the type of superplasticizers used in the concrete. As superplasticizer is used, the water content can be reduced up to 30%.

Based on the trails water content reduction of 29% is achieved with plasticizer.

Hence, The Percentage of reduction in water content = 27%

Water Content required after Super Plasticizer is added = 197 - (0.20*197)

                                                                                = 143 Litre.

 

STEP 6:

CALCULATION OF CEMENT CONTENT:

Adopted W/C ratio = 0.45.

Total Cement Required = Water Content / Water-Cement ratio

                                                                            = 143 / 0.35

                                                                            = 410 kg/m^3 > 360 kg/m^3. Hence OK.

 

STEP 7:

COARSE AND FINE AGGREGATE:

Coarse Aggregate ratio = 0.62 ; Table 3 - IS 10262 (For W/C=0.5).

Coarse Aggregate ratio for 0.35 W/C ratio = 0.65 ( Adding 0.01 for every decrease 0.05 and vice cersa).

For pumpable concrete these values are reduced by 10%

Therefore, The Volume of Coarse Aggregate = 0.65 * 0.9 = 0.585

Final Fine Aggregate ratio = 0.415 ; (1-0.585 = 0.415).

 

STEP 8:

MIX CALCULATIONS OF M50 GRADE CONCRETE:

A	Volume of Concrete	= 1 cu.m
B	Total Volume of Cement	= Mass of Cement / (S.G * 1000)
		= 410 / (3.15*1000)
		= 0.130 cu.m
C	Volume of Water	= Mass of Water / (S.G * 1000)
		= 143 / (1*1000)
		= 0.143 cu.m
D	Volume of Superplasticizers	= Mass of Superplasticizers / (S.G * 1000)
		= 8.2 / (1.145 * 1000)
		= 0.007 cu.m
E	Total Aggregate Requirement	= A-(B+C+D+E)
		= 1-(0.130+0.143+0.007)
		= 0.72 cu.m
F	Mass of Coarse Aggregate	= F * C.A ratio * S.G * 1000
		= 0.72 * 0.585* 2.74 * 1000
		= 1154 kg
G	Mass of Fine Aggregate	= F * F.A * ratio * S.G * 1000
		= 0.72 * 0.415 * 2.74 * 1000
		= 821.7 kg

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

RESULT:

Cement, Fine Aggregate, Coarse Aggregate, Water and Superplasticizer, Water-Cement ratio needed for M50 grade of concrete.

S.No	MATERIALS	QUANTITY
1	Cement	410 kg/m^3
3	Fine Aggregate	822 kg/m^3
4	Coarse Aggregate (20mm)	1154 kg/m^3
5	Water	143 kg/m^3
6	Chemical Admixture	7 kg/m^3
7	Water-Cement Ratio	0.35

 

 

 

 

 

 

 

 

 

 

To find the design mix ratio divide the calculated value all material by weight of cement.

Therefore Mix Ratio of M50 grade Concrete by weight is Cement : F.A : C.A  = 1 : 2.0 : 2.81.

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