Project on Concrete Mix Design for various grades of Concrete

1. Calculation of mix design for M35 grade concrete with fly ash.

Aim: Calculation of mix design for M35 grade concrete with fly ash.

Procedure:

1)Data:

• Grade of concrete : M35
• Type of cement = OPC 43 grade conforming to IS 8112
• Type of mineral admixture =fly ash conforming to IS 3812 (part 1).
• Maximum size of aggregate = 20 mm
• Minimum cement content =320 kg /m13. (From table 5 of IS 456: 2000 exposure condition).
• Maximum water cement ratio – 0.45. (From table 5 of IS 456 :2000 condition is exposure ).
• Workability = 100 mm (slump for pumpable concrete).
• Exposure condition = sever for reinforcement concrete.
• Method of concrete placing = pumping
• Degree of supervision = Good.
• Maximum cement content = 450 kg/m^3.
• Admixture = superplasticizer.

2)Test data for materials:

• Cement = OPC 43 grade conforming to IS 8112.
• Specific gravity of cement =-3.15
• Fly ash conforming to 3812 part 1
• Specific gravity of fly ash = 2.2
• Admixture = superplasticizer conforming to IS 9103.
• Specific gravity of course aggregate and fine aggregate = 2.74.
• Water absorption
• Course aggregate = 0.5 %
• Fine aggregate = 1.0 %
• Slive analysis = course aggregate conforming to table 2 of is 383 and fine aggregate

Conforming to grading zone 1 of the table is 383

3)To calculate the target mean strength:

• As per IS 10262: 2009 the standard deviations = 5 N/mm^2

F'ck = Fck +1.65 xS

F’ck = 35 + 1.65 x5 = 43.25 N/mm^2

Target mean strength = 43.25N/mm^2

4)Selection of water cement ratio :

• From table 5 IS 456:2000 for severe exposure the maximum w/c ratio is 0.45. Based on experience adopted water cement ratio is 0.40

0.40 <0.45, Hence value is ok.

5)Selection of water content:

• From table 2 of IS 10262:2009 the maximum water content of 20 mm aggregate is 186 lit.(For 25 mm to 50 mm slump). Additional 3 % slump is increased for per 25 mm slump.
• Estimated water content for 100 mm slump = 186 + 6/100 x 186 = 197 lit.
• Due to superplasticizer 30 % water content can be reduced.

Based on trial 29 % achieved with plasticizer.

Hence, arrived water content 197 0.71 = 140 lit.

6)Calculation of cement content:

• w/c ratio = 0.40
• Cementious material (cement+ fly ash)
• Cement content = (140/0.4) = 350 kg /m^3.

From table 5 of IS 456 : 2000 minimum cement content for severe exposure condition is 320 Kg/m^3.

350 Kg/ m^3 > 320 Kg/m^3, Hence ok.

Now,

7)Preparing the mix containing fly ash the following steps are fallow:

• The % of fly ash needed to be decide. Based on requirements and quality of materials.
• In this design mix we increase the 10 % of cementious material contant.

Cementious material content = 350x110 =385 kg/m^3.

• Water content = 140 kg/m^3.

So, w/c ratio = (140/385) = 0.364.

• Fly ash @ 30% of cementious material content = 385 x 30 % = 115 kg/m^3.
• Cement OPC = 385 -115 kg/m^3.
• Saving of cement with using fly ash = 350 -270= 80 kg/m^3

Fly ash being utilised = 115 kg/m^3.

6)Proportion of fine and course aggregate:

• Fine aggregate content from table 3 of IS 10262: 2009 volume of course aggregate
• Corresponding to 20 mm size of aggregate and fine aggregate (zone 1) from w/c ratio is 0.6
• In present case w/c ratio = 0.4

Therefore increase the volume of course aggregate and decrease the fine aggregate. w/c ratio is lower by 0.10 the proportion of volume of course aggregate is increasing by 0.02

Therefore corrected volume of coarse aggregate for the w/c ratio 0.4 = 0.62.

• For pumpable concrete this volume is reduced by 10 % .

Hence,

• Volume of coarse aggregate = 0.62 x 0.9 = 0.56
• Volume of fine aggregate = 1-0.56 = 0.44.

7)Mix calculation:

• Volume of concrete=1 m^3
• Volume of cement = (mass of cement / specific gravity of cement ) X ( 1/1000).

= (270/3.15) (1/1000) = 0.0086 m^3

• Volume of cement = 0.0086 m^3
• volume of fly ash = ( mass of fly ash / specific gravity of fly ash ) x (1/1000).

= (115/2.2) x (1/1000)= 0.052 m^3

• Volume of fly ash = 0.052 m^3
• Volume of water = (mass of water / specific gravity of water ) x (1/1000)

= (140/1)x(1/1000)= 0.140 m^3

• Volume of water = 0.140 m^3.
• volume of chemical admixture= (mass of chemical admixture/ specific gravity of chemical Admixture) x ( 1/1000).

= (7.6/1.145) (1/1000) = 0.006 m^3

• Volume of chemical admixture: 0.006 m43.
• Volume of aggregate (FA&CA) = (volume of concrete –(volume of cement + volume of fly Ash + volume of water + volume of chemical admixture )

= (1-(0.086+0.052+0.140+0.006))= 0.716 m^3

• Volume of aggregate = 0.716 m^3
• Mass of course aggregate = ( Volume of aggregate x volume of coarse aggregate x specific Gravity of course aggregate x 1000).

i.e. 0.716 x 0.56 x 2.74x1000 = 1098 kg/m^3

• Mass of course aggregate = 1098 kg/m^3
• Mass of fine aggregate = (volume of aggregate x volume of fine aggregate x specific gravity of Fine aggregate x 1000)

= 0.716x0.44 x 2.74x1000 = 863 kg/m^3

• Mass of fine aggregate = 863 kg /m^3

8)Mix proportion for trial No 1:

• Cement:270 kg/m^3
• Fly ash : 115 kg/m^3
• Water: 140 kg/m^3
• Fine aggregate : 863 kg/m^3
• Coarse aggregate : 1098 kg/m^3
• Chemical admixture : 7 kg/m^3
• Water cement ratio : 0.364

9)Results:

• Trial mix ratio = 1 : 2.24 : 1.85

2.Calculation of concrete mix design for M50 grade of concrete without fly ash.

Aim: Calculation of mix design for M35 grade concrete without fly ash.

Procedure:

1)Data

• Type of cement: OPC 43 grade conforming to IS 8112.
• Maximum size of aggregate : 20 mmm
• Minimum cement content: 320 kg/m^3 ( From table 5 of IS 456:2000 exposure condition.)
• Maximum w/c ratio: 0.45 .(From table 5 of IS 456 : 2000 exposure condition).
• Workability: 100mm ( Slump value of pumpable concrete).
• Exposure condition : severe for reinforced concrete.
• Method of concrete placing: pumping
• Degree of supervision: Good
• Type of aggregate: crushed angular aggregate
• Maximum cement content: 450 kg/m 1,3
• Chemical admixture : superplasticizer.

2)Test data for materials:

• Cement used: OPC 43 grade conforming to IS 8112.
• Specific gravity of cement: 3.15
• Chemical admixture : superplasticizer conforming to IS 9103
• Specific gravity of course aggregate and fine aggregate : 2.74

• Water absorption
• Course aggregate: 0.5%
• Fine aggregate 1.0%
• Free super moisture
• Course aggregate : Nil
• Fine aggregate : Nil
• Slive analysis : The course aggregate conforming to table 2 of IS 383 and fine aggregate

Conforming to grading zona I of table of IS 383.

3)Calculation of target mean strength for mix:

• Standard deviations : 5 N/mm^2

Fck = Fck +1.65 S

Fck = 50+ 1.65*5 = 58.25 N/mm^2

Target mean strength : 58.25 N/mm^2

4)Selection of water cement ratio :

• From table 5 of IS 456 : 2000 for severe exposure maximum w/c ratio is 0.45. Based on experience adopted w/c ratio is 0.40.

0.40<0.45 Hence ok

• From table 2 of is 10262:2009 maximum water content for 20 mm aggregate is 186 lit.(For 25 mm to 50 mm slump range ).
• Estimated water content for 100 mm slump

i.e. 186+ (6/100) x 186 = 197 mm

As per superplasticizer is used to water content can be reduced up to 20 % and above. Based on trials water content reduced of 29 % is achieved with plasticizer.

Hence,

The arrived water content= 197 x 0.71 = 140 lit.

• Water cement ratio : 0.4
• Cement content: 140/0.4 = 350 kg/m^3

From table 5 IS 456 minimum cement content for servere exposure condition is 320 kg/m^3

350 kg/m^3 >350 kg/m^3 ,Hence ok.

5)Proportion of volume of coarse aggregate and fine aggregate content:

• From table 3 of IS 10262 : 2009 volume of course aggregate corresponding to 20 mm size Aggregate and fine aggregate zone I for w/c ratio is 0.6.
• In present case w/c ratio is 0.40
• Therefore, the volume of course aggregate needs to increase to decrease the fine aggregate.
• As per w/c ratio is lower by the 0.10 and proportion of volume of coarse aggregate is Increased by 0.02.
• Hence, corrected volume of coarse aggregate for the water cement ratio of 0.40 = 0.62

For pumpable concrete value is reduced by 10%.

• Volume of coarse aggregate = 0.62 x 0.9 =0.56
• Volume of fine aggregate= 1-0.56= 0.14

6)Mix calculation :

• Volume of concrete: 1 m^3
• Volume of cement = (mass of cement /specific gravity of cement )x (1/1000)

=(350/3.15) x ( 1/1000) = 0.111m13

• Volume of cement = 0.111 m^3
• Volume of water = (mass of water / specific gravity of water ) x (1/1000).

= (140/1)(1/1000)= 0.140 m^3

• Volume of water = 0.140 m^3
• Volume of chemical admixture = (mass of chemical admixture / specific gravity of chemical admixture ) x (1/1000)

=(7.6/1.145 ) × (1/1000) = 0.006m^3

• Volume of chemical admixture = 0.006m^3
• Volume of aggregate (Fa& CA) = ( volume of concrete - ( volume of cement+ volume of water + volume of chemical admixture ))

= (1- (0.111+ 0.140+0.006))= 0.743 m^3

• Volume of aggregate = 0.743 m^3
• Mass of course aggregate = (volume of aggregate x volume of course aggregate specific gravity of course aggregate x1000)

= 0.743x0.56x2.74x1000 = 1140 kg/m^3

• Mass of coarse aggregate = 1140 kg/m^3.
• Mass of fine aggregate = (volume of aggregatex volume of fine aggregate x specific gravity of fine aggregate x 1000).

=0.743x 0.44 x 2.74 x 1000 = 896 kg/m^3

• Mass of fine aggregate = 896 kg/m^3

7)Mix proportion :

• Cement:350 kg/m^3
• Water: 140 kg/m^3
• Fine aggregate : 896 kg/m^3
• Coarse aggregate : 1140kg/m^3
• Chemical admixture : 7 kg/m^3
• Water cement ratio : 0.4

8)Result:

Trial mix = 1: 2.56 : 3.26.