Project on Concrete Mix Design for various grades of Concrete

PROJECT 1

Concrete Mix Design for M50 grade concrete without fly ash:

AIM:

To calculate the concrete Mix Design for M50 grade concrete without fly ash

INTRODUCTION:

Concrete mix design is the method of finding the precise proportion of cement, sand and aggregate for concrete to achieve the target strength in structures, therefore concrete mix design can be stated as concrete mix in terms of Cement : Sand : Aggregates. the design is done according to the requirement of concrete strength. The fresh concrete properties like workability, setting time and hardened concrete properties like admixture, retarders etc.. The project consist of two parts, the first part deal with the design of M50 grade concrete cement with flyash.

PROCEDURES TO FIND THE MIX DESIGN:

1.STIPULATIONS FOR PROPORTIONING :

A) Grade of destination : M50

B) Type of cement : OPC 43 grade conforming to IS 8112

C) Maximum nominal size of aggregate : 20 mm

D) Minimum cement content : 320 kg/m³ (from table 5 of IS 456:2000 – exposure condition

E) Minimum Water / cement ratio : 0.45 (from table 5 of IS 456:2000 – exposure condition)

F) Workability : 100 mm

G) Exposure condition : Severe (for reinforced concrete)

H) Method of concrete placing : pumping

I) Type of aggregate: crushed angular aggregate

J) Degree of supervision: Good

K) Maximum cement content = 450 kg/m³

L) Chemical admixture type : superplasticizer

2.Test data for materials :

1. Cement used : OPC 43 grade conforming to IS 8112
2. Specific gravity of cement : 3.15
3. Chemical admixture : superplasticizer conforming to IS 9103
4. Specific gravity of coarse aggregate :2.74
5. Specific gravity of fine aggregate : 2.74
6. Water absorption of coarse aggregate : 0.5%
7. Water absorption of fine aggregate : 1.0%
8. Free surface moisture of coarse aggregate : nil
9. Free surface moisture of fine aggregate = nil
10. Sieve analysis test on coarse aggregate : conforming to grading zone 1 of table 2 of IS 383
11. Sieve analysis test on fine aggregate : conforming to grading zone 1 of table 4 of IS 383

3.Target strength for Mix proportion :

f’ck = fck + 1.65S

where f’ck = target average compressive strength at 28 days

fck = characteristic compressive strength at 28 days

S = standard deviation

From table 1 of IS 10262 : 2009 , standard deviation S= 5 N/mm²

Target strength = 50 + 1.65 x (5)

= 58.25 N/mm²

4.selection of w/c ratio :

From table 5 of IS 456:2000 for severe exposure, maximum w/c ratio is 0.45

Based on experience , adopt w/c ratio as 0.40 < 0.45

Hence O.K

5.selection of water content :

From table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 litres (For 25 mm to 50 mm slump range)

Estimated water content for 100 mm slump

W/C = 186 + (6/100 x 186)

= 197 litres

As super plasticizer is used , the w/c can be reduced upto 30%

Based on trials water content reduction of 29% is achieved with plasticizer

Hence the arrived water content = 197 x 0.71 = 140 litres

6.Calculation of cement content:

W/C ratio : 0.4

Cementious Material

(Cement) content

= 140 / 0.4

= 350 kg/m³

From table 5 of IS 456 minimum cement content for “severe” exposure condition = 320 kg/m³

350 kg/m³ > 320 kg/m³

Hence O.K

7.Proportion of volume of coarse aggregate and fine aggregate content:

from table 3 of IS 10262:2009, volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone 1) for W/C ratio = 0.6

In the present case the W/C ratio is 0.40

The Volume of coarse aggregate needs to be increases to decreases the fine aggregate content

As W/C ratio is lower by 0.10 , the proportion of volume of coarse aggregate is increased by 0.02 (at the rate of (+/-) 0.01 and for every +/- 0.05 change in W/C ratio

Therefor the corrected volume of coarse aggregate for W/C Ratio of 0.40 = 0.62

Note: If coarse aggregate is not of angular type , then also the volume of coarse aggregate may be required to be increased suitably, based on experience)

For Pumpable concrete these values are reduced by 10%

Volume of coarse aggregate = 0.62 x 0.9 = 0.56

Volume of fine aggregate = 1 – 0.56 = 0.44

8.Mix Calculations:

The Mix calculations per unit Volume of concrete shall be as follows:

1. Volume of concrete = 1m³
2. Volume of cement = mass of cement / specific gravity of cement x 1/1000

= 350/3.15 x 1/1000 = 0.111 m³

3.Volume of Water = Mass of Water / specific gravity of water x 1/1000

= 140/1 x 1/1000

= 0.140 m³

4.Volume of Chemical admixture = Mass of chemical admixture/ specific gravity of admixture x 1/1000

= 7.6 / 1.145 x 1/1000

= 0.006 m³

5.Volume of aggregate (F.A + C.A )

= a – (b+c+d+e)

= 1 – (0.111 + 0.140 + 0.006)

= 0.743 m³

6.Mass of coarse aggregate

= f x volume of Coarse aggregate x specific Gravity of coarse aggregate x 1000

= 0.743 x 0.56 x 2.74 x 1000

= 1140 Kg/m³

7.Mass of fine aggregate

= f x Volume of fine aggregate x specific Gravity of aggregate x 1000

= 0.743 x 0.440 x 2.74 x 1000

= 896 Kg/m³

9.Mix Proportions for trial number 1:

RESULT:

Cement = 350 Kg/m³

Water = 140 Kg/m³

F.A = 896 Kg/m³

C.A = 1140 Kg/m³

Chemical admixture = 7 Kg/m³

W/C Ratio = 0.4

Trial Mix Ratio = 1 : 2.56 : 3.26

Hence the mix design is found for the M50 grade of concrete without Flyash and the ratio is 1 : 2.56 : 3.26

Concrete Mix Design for M35 grade concrete with fly ash:

AIM:

To calculate the concrete Mix Design for M35 grade concrete with fly ash

INTRODUCTION:

Concrete mix design is the method of finding the precise proportion of cement, sand and aggregate for concrete to achieve the target strength in structures, therefore concrete mix design can be stated as concrete mix in terms of Cement : Sand : Aggregates. the design is done according to the requirement of concrete strength. The fresh concrete properties like workability, setting time and hardened concrete properties like admixture, retarders etc.. The project consist of two parts, the Second part deal with the design of M35 grade concrete cement with flyash.

PROCEDURES TO FIND THE MIX DESIGN:

1.Stipulations for proportioning :

A) Grade of destination : M35

B) Type of cement : OPC 43 grade conforming to IS 8112

C) Type of mineral admixture : flyash conforming to IS 3812 (PART 1)

D) Maximum nominal size of aggregate : 20 mm

E) Minimum cement content : 320 kg/m³ (from table 5 of IS 456:2000 – exposure condition

F) Minimum Water / cement ratio : 0.45 (from table 5 of IS 456:2000 – exposure condition)

G) Workability : 100 mm

H) Exposure condition : Severe (for reinforced concrete)

I) Method of concrete placing : pumping

J) Type of aggregate: crushed angular aggregate

K) Degree of supervision: Good

L) Maximum cement content = 450 kg/m³

M) Chemical admixture type : superplasticizer

2.Test data for materials :

1. Cement used : OPC 43 grade conforming to IS 8112
2. Specific gravity of cement : 3.15
3. Fly ash : conforming to IS 3812 (part 1)
4. Specific gravity of flyash : 2.2
5. Chemical admixture : superplasticizer conforming to IS 9103
6. Specific gravity of coarse aggregate :2.74
7. Specific gravity of fine aggregate : 2.74
8. Water absorption of coarse aggregate : 0.5%
9. Water absorption of fine aggregate : 1.0%
10. Free surface moisture of coarse aggregate : nil
11. Free surface moisture of fine aggregate = nil
12. Sieve analysis test on coarse aggregate : conforming to grading zone 1 of table 2 of IS 383
13. Sieve analysis test on fine aggregate : conforming to grading zone 1 of table 4 of IS 383

3.Target strength for Mix proportion :

f’ck = fck + 1.65S

where f’ck = target average compressive strength at 28 days

fck = characteristic compressive strength at 28 days

S = standard deviation

From table 1 of IS 10262 : 2009 , standard deviation S= 5 N/mm²

Target strength = 35 + 1.65 x (5)

= 43.25 N/mm²

4.selection of w/c ratio :

From table 5 of IS 456:2000 for severe exposure, maximum w/c ratio is 0.45

Based on experience , adopt w/c ratio as 0.40 < 0.45

Hence O.K

5.selection of water content :

From table 2 of IS 10262:2009, maximum water content for 20 mm aggregate = 186 litres (For 25 mm to 50 mm slump range)

Estimated water content for 100 mm slump

W/C = 186 + (6/100 x 186)

= 197 litres

As super plasticizer is used , the w/c can be reduced upto 30%

Based on trials water content reduction of 29% is achieved with plasticizer

Hence the arrived water content = 197 x 0.71 = 140 litres

6.Calculation of cement content:

W/C ratio : 0.4

Cementious Material

(Cement + flyash) content

= 140 / 0.4

= 350 kg/m³

From table 5 of IS 456 minimum cement content for “severe” exposure condition = 320 kg/m³

350 kg/m³ > 320 kg/m³

Now, to proportion a mix containing flyash the following steps are suggested

1. The percentage of flyash needs to be decided based on project requirement and quality of materials
2. In some cases increase in cementitious material can be warranted . Increase in cementitious material content and its percentage may be based on experience and trial

Cementitious material content = 350 x 1.10 = 385 kg/m³

Water content = 140 kg/m³

W/C ratio = 140/385 = 0.364

Flyash @ 30 % total cementitious material content

= 385 x 30%

= 115 Kg/m³

Cement (OPC) = 385 -115

= 270 Kg/m³

Saving of cement while using Flyash = 350 -270

= 80 Kg/m³

Flyash used = 115 kg/m³

7.Proportion of volume of coarse aggregate and fine aggregate content: from table 3 of IS 10262:2009, volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone 1) for W/C ratio = 0.6

In the present case the W/C ratio is 0.40

The Volume of coarse aggregate needs to be increases to decreases the fine aggregate content

As W/C ratio is lower by 0.10 , the proportion of volume of coarse aggregate is increased by 0.02 (at the rate of (+/-) 0.01 and for every +/- 0.05 change in W/C ratio

Therefor the corrected volume of coarse aggregate for W/C Ratio of 0.40 = 0.62

Note: If coarse aggregate is not of angular type , then also the volume of coarse aggregate may be required to be increased suitably, based on experience)

For Pumpable concrete these values are reduced by 10%

Volume of coarse aggregate = 0.62 x 0.9 = 0.56

Volume of fine aggregate = 1 – 0.56 = 0.44

8.Mix Calculations:

The Mix calculations per unit Volume of concrete shall be as follows:

1. Volume of concrete = 1m³
2. Volume of cement = mass of cement / specific gravity of cement x 1/1000

= 270/3.15 x 1/1000 = 0.086 m³

3.Volume of flyash = Mass of flyash / specific gravity of flyash x 1/1000

= 115/2.2 x 1/1000

= 0.052 m³

4.Volume of Water = Mass of Water / specific gravity of water x 1/1000

= 140/1 x 1/1000

= 0.140 m³

5.Volume of Chemical admixture = Mass of chemical admixture/ specific gravity of admixture x 1/1000

= 7.6 / 1.145 x 1/1000

= 0.006 m³

6.Volume of aggregate (F.A + C.A )

= a – (b+c+d+e)

= 1 – (0.086 + 0.052 + 0.140 + 0.006)

= 0.716 m³

7.Mass of coarse aggregate

= f x volume of Coarse aggregate x specific Gravity of coarse aggregate x 1000

= 1098 Kg/m³

8.Mass of fine aggregate

= f x Volume of fine aggregate x specific Gravity of aggregate x 1000

= 0.716 x 0.440 x 2.74 x 1000

= 863 Kg/m³

9.Mix Proportions for trial number 1:

RESULT:

Cement = 270 Kg/m3

Flyash = 115 Kg/m3

Water = 140 Kg/m3

F.A = 863 Kg/m3

C.A = 1098 Kg/m3

Chemical admixture = 7 Kg/m3

W/C Ratio = 0.364

Trial Mix Ratio = 1 : 2.24 : 2.85

Hence the mix design is found for the M35 grade of concrete with Flyash and the ratio is 1 : 2.24 : 2.85