Project on Concrete Mix Design for various grades of Concrete

AIM - MIX Design for M 35 grade concrete with fly ash

Procedure :

Step :1

Stipulation for proportioning

1. Grade of designation - M 35
2. Type of cement - OPC 43 Grade conforming to IS 3812 ( part )
3. Type of mineral admixture - fly ash confirming to 3812 (Part 1)
4. Minimum cement content : 320kg/ M3 ( table : 5 IS 456: 2000, based on exposure condition)
5. Maximum nominal size of aggregates: 20 mm
6. Maximum water cement ratio : 0.45 ( table :5 IS 456:2000,based on exposure condition)
7. Workability : 100mm slump value of pumpable concrete
8. Exposure condition : severe ( for reinforced concrete )
9. Method of concrete placing - pumping
10. Degree of supervision: Good
11. Types of aggregates : crushed angular aggregates
12. Maximum cement content - 450 kg / M3
13. Chemical admixture type : superplasticizer

Step 2

Test data for materials

• Cement used : OPC 43 Grade confirming to IS 8112
• Specific gravity of cement : 3.15
• Fly ash : conforming to IS 3812 part 1
• Specific gravity of fly ash - 2.2
• Chemical admixture : superplasticizer conforming to IS 9103
• Specific gravity of - course aggregates - 2.74 , fine aggregates - 2.74 .
• Water absorption : course aggregates : 0.5%,fine aggregates : 1%
• Free surface moisture: course aggregates - nil ,fine aggregates - nil
• Seive analysis - coarse aggregate ( confirming to table 2 of IS 383 ,fine aggregates ( confirming to grading zone 1 of table 4 Is 383

Step 3 -

To find Target mean strength for proportioning .

Target mean strength :- f'ck = fck +1.65 s

= 35 + 1.65 *5 = 43.25 N/mm2

Fck - characteristic strength

S - standard deviation

Step 4 -

Selection of water cement ratio

Maximum water cement ratio - 0.45

Based on experience water - cement ratio = 0.4

0.4<0.45,hence OK .

Step 5 -

Selection of water content Maximum water content for 20 mm aggregates = 186 lit ( table 2 of IS 1026:2009 ) for 25 mm to 55 mm slump range

For 100 mm slump range = 186 + ( 6/100) = 197 litres

As superplasticizer is used the water content is reduced upto 30 %

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

Hence arrived water content - 197 *0.71 = 140 litres

Step 6 -

Calculation of cement ratio

Water - cement ratio - 0.4

Cement content = 140 / 0.4 = 350 kg/ M3

In table of IS 456-2000 the cement content for severe exposure= 320 kg/M3

350kg/M3 > 320 kg /M3

Hence ok

To preparation the mix containing flyash the following step are suggested

• The percentage of flyash need to be decided based on project requirement and quality of materials.
• In some cases increase on cementitious materials can be warned. Increase in cementitious materials Content and it's percentage may be based on experience and trial, in this increase 10% cementitious material is considered.
• Cementitious material content = 350 *1.1 = 385 kg /M3
• Water content - 140 kg /M3

So water - cement ratio = 140/ 385= 0.364

Fly ash at 30 % total cementitious content = 35-30%= 115kg/M3

Cement ( OPC ) = 385- 115= 270 kg/M3

Saving of cement while using flyash - 350- 270 = 80 kg/M3

Fly begin utilized = 115 kg /M3

Step 7 -

Proportion of volume of coarse and fine aggregates content

From table 3 of IS 1026: 2009 , volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate ( zone 1 ) for water - cement ratio = 0.6

In present case water cement ratio is 0.4

Therefore the volume of coarse aggregate need to be increased to decrease the fine aggregates content

As the water cement ratio is lowered by 0.1 , the proportion of the volume of coarse aggregate is increased by 0.02 (at the rate of +/- 0.01 for every +/- 0.05 change in water cement ratio)

Hence the corrected value of coarse aggregate for the water cement ratio = 0.64

( If coarse aggregate is not of angular type , then also the value of coarse aggregate may be required to be increased suitably,based on experience.)

For pumpable concrete, these are reduced by 10% .

Volume of coarse aggregate - 0.64*0.9= 0.576

Volume of fine aggregates - 1- 0.576= 0.424

Step 8

Mix calculation

Mix calculation per unit volume of concrete

a. Volume of concrete - 1 M3

b. Volume of cement = ( mass of cement/ specific gravity of cement) * 1000

= ( 270/3.15)*1/1000= 0.086m3

c. Volume of flyash = ( mass of cement/ specific gravity of cement) * 1000

=(115/2.2)*1/1000= 0.052 M3

d. Volume of water = ( mass of cement/ specific gravity of cement) * 1000

= (140/1)*1/1000= 0.14 M3

e. Mass of coarse aggregate - f* volume of coarse aggregates*specific gravity of course aggregates*1000

= 0.716*0.576*2.74*1000= 1130kg/M3

h. Mass of coarse aggregate - f* volume of fine aggregates*specific gravity of fine aggregates*1000*

=0.716*0.424*2.74*1000= 831kg/M3

Step 9

Mix proportion

Cement - 270kg/M3

Fly ash - 115kg / M3

Water - 140kg/M3

Fine aggregates - 832kg /M3

Coarse aggregate - 831kf /M3

Chemical admixture -7 kg /M3

Water cement ratio - 0.364

Mix ratio 1:2.15:2.94

Step 10

The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump on trail . The mix proportion shall be reworked for the actual water content and checked for durability requirements .

Step 11

Two or more trials having variation of 10% of water cement ratio in clause 10 ( step 10 ) shall be carried out a graph between three water cement ratios and corresponding strength shall be plotted to work out the mix proportions for the given target strength for field trial. However durability shall be met

Results - Mix ratio for M35 1:2.15:2.94

AIM - MIX Design for M 50 grade concrete with fly ash

Procedure :

Step :1

Stipulation for proportioning

1. Grade of designation - M 50
2. Type of cement - OPC 43 Grade conforming to IS 3812 ( part )
3. Type of mineral admixture - fly ash confirming to 3812 (Part 1)
4. Minimum cement content : 320kg/ M3 ( table : 5 IS 456: 2000, based on exposure condition)
5. Maximum nominal size of aggregates: 20 mm
6. Maximum water cement ratio : 0.45 ( table :5 IS 456:2000,based on exposure condition)
7. Workability : 100mm slump value of pumpable concrete
8. Exposure condition : severe ( for reinforced concrete )
9. Method of concrete placing - pumping
10. Degree of supervision: Good
11. Types of aggregates : crushed angular aggregates
12. Maximum cement content - 450 kg / M3
13. Chemical admixture type : superplasticizer

Step 2

Test data for materials

• Cement used : OPC 43 Grade confirming to IS 8112
• Specific gravity of cement : 3.15
• Fly ash : conforming to IS 3812 part 1
• Specific gravity of fly ash - 2.2
• Chemical admixture : superplasticizer conforming to IS 9103
• Specific gravity of - course aggregates - 2.74 , fine aggregates - 2.74 .
• Water absorption : course aggregates : 0.5%,fine aggregates : 1%
• Free surface moisture: course aggregates - nil ,fine aggregates - nil
• Seive analysis - coarse aggregate ( confirming to table 2 of IS 383 ,fine aggregates ( confirming to grading zone 1 of table 4 Is 383

Step 3 -

To find Target mean strength for proportioning .

Target mean strength :- f'ck = fck +1.65 s

= 50+ 1.65 *5 = 58.25 N/mm2

Fck - characteristic strength

S - standard deviation

Step 4 -

Selection of water cement ratio

Maximum water cement ratio - 0.45

Based on experience water - cement ratio = 0.4

0.4<0.45,hence OK .

Step 5 -

Selection of water content Maximum water content for 20 mm aggregates = 186 lit ( table 2 of IS 1026:2009 ) for 25 mm to 55 mm slump range

For 100 mm slump range = 186 + ( 6/100) = 197 litres

As superplasticizer is used the water content is reduced upto 30 %

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

Hence arrived water content - 197 *0.71 = 140 litres

Step 6 -

Calculation of cement ratio

Water - cement ratio - 0.4

Cement content = 140 / 0.4 = 350 kg/ M3

In table of IS 456-2000 the cement content for severe exposure= 320 kg/M3

350kg/M3 > 320 kg /M3

Hence ok

Step 7 -

Proportion of volume of coarse and fine aggregates content

From table 3 of IS 1026: 2009 , volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate ( zone 1 ) for water - cement ratio = 0.6

In present case water cement ratio is 0.4

Therefore the volume of coarse aggregate need to be increased to decrease the fine aggregates content

As the water cement ratio is lowered by 0.1 , the proportion of the volume of coarse aggregate is increased by 0.02 (at the rate of +/- 0.01 for every +/- 0.05 change in water cement ratio)

Hence the corrected value of coarse aggregate for the water cement ratio = 0.64

( If coarse aggregate is not of angular type , then also the value of coarse aggregate may be required to be increased suitably,based on experience.)

For pumpable concrete, these are reduced by 10% .

Volume of coarse aggregate - 0.64*0.9= 0.576

Volume of fine aggregates - 1- 0.576= 0.424

Step 8

Mix calculation

Mix calculation per unit volume of concrete

a. Volume of concrete - 1 M3

b. Volume of cement = ( mass of cement/ specific gravity of cement) * 1000

= ( 350/3.15)*1/1000= 0.111m3

c. Volume of water = ( mass of cement/ specific gravity of cement) * 1000

= (140/1)*1/1000= 0.14 M3

d. volume of chemical admixture - mass os admixture / specific gravity of admixture)*1/1000=( 7.6/1.145)* 1/1000= 0.006m3

e. Volume of aggregates - ( fine adn coarse ) = a- (b+c+d)

=1-(0.111+0.14+0.006)=0.743m3

f. Mass of coarse aggregate - f* volume of coarse aggregates*specific gravity of course aggregates x 1000

= 0.743*0.576*2.74*1000=1173kg/m3

g. Mass of coarse aggregate - f* volume of fine aggregates*specific gravity of fine aggregates*1000*

=0.743*0.424*2.74*1000= 863kg/M3

Step 9

Mix proportion

Cement - 350kg/M3

Water - 140kg/M3

Fine aggregates - 863kg /M3

Coarse aggregate - 1173kf /M3

Chemical admixture -7 kg /M3

Water cement ratio - 0.4

Mix ratio 1:2.46:3.35

Step 10

The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump on trail . The mix proportion shall be reworked for the actual water content and checked for durability requirements .

Step 11

Two or more trials having variation of 10% of water cement ratio in clause 10 ( step 10 ) shall be carried out a graph between three water cement ratios and corresponding strength shall be plotted to work out the mix proportions for the given target strength for field trial. However durability shall be met

Result - Mix ratio for M50 1:2.46:3.35