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

INTRODUCTION

Concrete is the most commonly used material in civil construction work all over the world.The various ingredients of concrete are cement,coarse aggregate,fine aggregate,water,admixtures etc..The process of selecting suitable ingredients of concrete and determining their relative amounts with the objective of producing a concrete of required strength, durability, and workability as economically as possible, is termed as concrete mix design

OBJECTIVE

To produce mix design for M35 grade concrete with fly ash & M50 grade concrete without Fly ash

PROCEDURE

1.Concrete Mix Design for M35 grade concrete with fly ash

STEP 1: Stipulations for Concrete design mix

Grade designation: M35

Type of cement: OPC 43 grade

Type of mineral admixture : Fly ash conforming to IS 3812 (Part 1)

Maximum nominal size of aggregate:20mm

Minimum cement content:320 Kg (From Table 5 of IS 456:2000)

Maximum water-cement ratio: 0.45 (From Table 5 of IS 456:2000)

Degree of Workability: 100mm slump

Exposure condition: Sever

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: Superplasticizer

STEP 2:Test Data for Material

Cement used : OPC 43 Grade conforming to IS 8112

Specific gravity of cement : 3.15

Chemical admixture : Super plasticizer conforming to IS 9103

Specific gravity of fly ash : 2.2

Specific gravity of coarse aggregate : 2.74

Specific gravity of fine aggregate : 2.74

Water absorption of coarse aggregate : 0.5%

Water absorption of fine aggregate : 1.0%

Free surface moisture of coarse aggregate : Nil (The aggregate should be in dry condition and doesn't use wet condition)

Free surface moisture of fine aggregate : Nil

Sieve Analysis : Test for coarse aggregate should conforming to Table-2 of IS 383

Sieve Analysis : Test for fine aggregate should conforming to Grading of Zone-II of table-4 of IS 383

Step 3: Determination of Target Strength of concrete

Target mean strength f’ck= fck +(1.65*S)

where

f’ck= target average compressive strength at 28 days

fck = characteristics compressive strength at 28

s = standard deviation

From Table 1 of IS 10262:2009 the standard deviation for M35 grade concrete is

s =, S = 5 N/mm^2

Target mean strength f’ck= 35+(1.65*5)

f’ck= 43.25 N/mm^2

Step 4: Determination of water cement ratio

From Table 5 of IS 456-2000

Exposure condition is Severe

Maximum water-cement ratio : 0.45

Based on the experience, we have adopted water-cement ratio : 0.44

0.44<0.45, hence OK

STEP 5 : Selection of water content

From Table-2 of IS 10262:2009.

Nominal size of aggregates = 20 mm

maximum water content for 25 to 50 mm slump range =186 litre

Here slump value is 100mm

As per Clause 4.2 .3% of water content must increase for every extra 25 mm slump from 50 mm slump.

Estimated water content for 100 mm slump =186+6/100 x 186

=197 liters

As superplasticizer is used water content is reduced up to 30%

As trail it can be 25%

water content = 197*0.75

= 147 liters

STEP 6 : Calculation of cementitious content (cement + fly ash)

Water cement ratio = 0.44

Water content = 147 liter

Cementitious content (cement + fly ash)= 147/0.44

=334 kg/m^3

From Table 5 of IS 456, Minimum cement content for ‘Severe’ exposure conditions is 320 kg/m^3

334 kg/m^3>320 kg/m^3

Hence ok

cementitious content is increased by 10%

New cementitious content =334*1.10 =367.4kg/m^3

Water content = 147 liter

New water cement ratio =147/367.4

=0.40

Fly ash content is taken as 30% of the total cementitious content=367.4*.3

=110.22

Cement required = 367.4 - 110.22 = 257.18 kg/m^3

Cement quantity saved using fly ash addition = 367.4 - 257.18= 110.22 kg/m^3

Step 7:Calculation of volume of coarse aggregate and fine aggregate

From Table 3 of I.S : 10262-2009 volume of coarse aggregate corresponding tor 20mm size aggregate and for fine aggregate (zone 2) water cement ratio 0.50 = 0.62

In the present case the water-cement ratio we have calculated is 0.40

So, 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)

So the value is 0.64

For pumpable concrete the value is reduced by 10%

Volume of coarse aggregate=0.64*.9

=0.576

Volume of fine aggregate= 1- 0.576

= 0.424

Step 8:Mix calculation

1. a) Volume of concrete = 1 m^3
2. b) Volume of cement = Mass of cement/Specific gravity of cement *(1/1000)

= 257.18/3.15*(1/1000)

=0.0815m^3

c)Volume of fly ash =Mass of fly ash/Specific gravity of fly ash *(1/1000)

=110.22/2.20*(1/1000)

=0.0501m^3

1. d) Volume of water = Mass of water/Specific gravity of water *(1/1000)

=147/1*(1/1000)

=0.147m^3

1. e) Volume of chemical admixtures = Mass of chemical admixture/Specific gravity of water *(1/1000)

=7.348/1.145*(1/1000)

=0.0062m^3

f)volume of aggregate(FA+CA) =a-(b+c+d+e)

=1-(0.0815+.05010+.140+0.0064)

=0.7222 m^3

1. g) Mass of coarse aggregates = e × Volume of coarse aggregate × Specific gravity of coarse aggregate × 100

=0.7222 x 0.576 × 2.74 × 1000 =1139.80 kg/m^3

1. h) Mass of fine aggregates = e × Volume of fine aggregate × Specific gravity of fine aggregate × 1000

=0.7222 x 0.424 × 2.74 × 1000 =839.02 kg/m^3

STEP 9 : RESULTS

Mix proportion

Cement =257.18kg/m^3

Fly ash =110.22kg/m^3

Water =147kg/m^3

Fine aggregate =839.02 kg/m^3

Coarse aggregates =1139.80 kg/m^3

Chemical admixtures =7.348 kg/m^3

Water cement ratio =0.40

Trail mix ratio =1:2.28:3.10

2.Concrete Mix Design for M50 grade concrete without fly ash

STEP 1: Stipulations for Concrete design mix

Grade designation: M50

Type of cement: OPC 43 grade

Maximum nominal size of aggregate:20mm

Minimum cement content:320 Kg (From Table 5 of IS 456:2000)

Maximum water-cement ratio: 0.45 (From Table 5 of IS 456:2000)

Degree of Workability: 100mm slump

Exposure condition: Sever

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: Superplasticizer

STEP 2:Test Data for Material

Cement used : OPC 43 Grade conforming to IS 8112

Specific gravity of cement : 3.15

Chemical admixture : Super plasticizer conforming to IS 9103

Specific gravity of fly ash : 2.2

Specific gravity of coarse aggregate : 2.74

Specific gravity of fine aggregate : 2.74

Water absorption of coarse aggregate : 0.5%

Water absorption of fine aggregate : 1.0%

Free surface moisture of coarse aggregate : Nil (The aggregate should be in dry condition and doesn't use wet condition)

Free surface moisture of fine aggregate : Nil

Sieve Analysis : Test for coarse aggregate should conforming to Table-2 of IS 383

Sieve Analysis : Test for fine aggregate should conforming to Grading of Zone-II of table-4 of IS 383

Step 3: Determination of Target Strength of concrete

Target mean strength f’ck= fck +(1.65*S)

where

f’ck= target average compressive strength at 28 days

fck = characteristics compressive strength at 28

s = standard deviation

From Table 1 of IS 10262:2009 the standard deviation for M35 grade concrete is

s =, S = 5 N/mm^2

Target mean strength f’ck= 50+(1.65*5)

f’ck= 58.25 N/mm^2

Step 4: Determination of water cement ratio

From Table 5 of IS 456-2000

Exposure condition is Severe

Maximum water-cement ratio : 0.45

Based on the experience, we have adopted water-cement ratio : 0.44

0.44<0.45, hence OK

STEP 5 : Selection of water content

From Table-2 of IS 10262:2009.

Nominal size of aggregates = 20 mm

maximum water content for 25 to 50 mm slump range =186 litre

Here slump value is 100mm

As per Clause 4.2 .3% of water content must increase for every extra 25 mm slump from 50 mm slump.

Estimated water content for 100 mm slump =186+6/100 x 186

=197 liters

As superplasticizer is used water content is reduced up to 20%

As trail it can be 20%

water content = 197*0.80

= 158 liters

STEP 6 : Calculation of cement content

Water cement ratio = 0.44

Water content = 158 liter

Cement content = 158/0.44

=359 kg/m^3

From Table 5 of IS 456, Minimum cement content for ‘Severe’ exposure conditions is 320 kg/m^3

359 kg/m^3>320 kg/m^3

Hence ok

Step 7:Calculation of volume of coarse aggregate and fine aggregate

From Table 3 of I.S : 10262-2009 volume of coarse aggregate corresponding tor 20mm size aggregate and for fine aggregate (zone 2) water cement ratio 0.50 = 0.62

In the present case the water-cement ratio we have calculated is 0.44

So, 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)

So the value is 0.632

For pumpable concrete the value is reduced by 10%

Volume of coarse aggregate=0.632*.9

=0.568

Volume of fine aggregate= 1- 0.568

= 0.432

Step 8:Mix calculation

1. a) Volume of concrete = 1 m^3
2. b) Volume of cement = Mass of cement/Specific gravity of cement *(1/1000)

= 359/3.15*(1/1000)

=0.114m^3

1. c) Volume of water = Mass of water/Specific gravity of water *(1/1000)

=158/1*(1/1000)

=0.158m^3

1. g) Volume of chemical admixtures = Mass of chemical admixture/Specific gravity of water *(1/1000)

=7.18/1.145*(1/1000)

=0.0062m^3

e)volume of aggregate(FA+CA) =a-(b+c+d)

=1-(0.114+.158+0.0062)

=0.7218m^3

1. f) Mass of coarse aggregates = e × Volume of coarse aggregate × Specific gravity of coarse aggregate × 100

=0.7218 x 0.568 × 2.74 × 1000 =1123.35 kg/m^3

1. g) Mass of fine aggregates = e × Volume of fine aggregate × Specific gravity of fine aggregate × 1000

=0.7218x 0.432× 2.74 × 1000 =854.38 kg/m^3

STEP 9 : RESULTS

Mix proportion

Cement =359kg/m^3

Water =158kg/m^3

Fine aggregate =854.38 kg/m^3

Coarse aggregates =1123.35 kg/m^3

Chemical admixtures =7.18 kg/m^3

Water cement ratio =0.40

Trail mix ratio =1:2.37:3.129

RESULTS

Mix proportion for M35 grade of concrete with fly ash

Cement =257.18kg/m^3

Fly ash =110.22kg/m^3

Water =147kg/m^3

Fine aggregate =839.02 kg/m^3

Coarse aggregates =1139.80 kg/m^3

Chemical admixtures =7.348 kg/m^3

Water cement ratio =0.40

Trail mix ratio =1:2.28:3.10

Mix proportion for M50 grade of concrete without fly ash

Cement =359kg/m^3

Water =158kg/m^3

Fine aggregate =854.38 kg/m^3

Coarse aggregates =1123.35 kg/m^3

Chemical admixtures =7.18 kg/m^3

Water cement ratio =0.40

Trail mix ratio =1:2.37:3.129

CONCLUSIONS

The Mix ratio for M35 grade of concrete using fly ash is obtained as 1:2.28:3.10(Cement : Fine Aggregate : Coarse Aggregate)

The Mix ratio for M50 grade of concrete 1:2.37:3.129(Cement : Fine Aggregate : Coarse Aggregate)

Using fly ash we can reduce the amount of cement used in the concrete