Project on Concrete Mix Design for various grades of Concrete

PROJECT

• Topic :
• Calculation of mix design for M35 grade concrete with fly ash.
• Calculation of mix design for M50 grade concrete without fly ash.

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 :
• 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 /m^3. ( 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 = severe for reinforcement concrete.
• Method of concrete placing = pumping.
• Degree of supervision = Good.
• Maximum cement content = 450 kg /m^3.
• Admixture = superplastisizer .
• 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 table IS 383
• To calculate the target mean strength :
• as per IS 10262: 2009 the standard deviations = 5 N/MM ^2

F'ck = Fck +1 .65 ×S

F'ck = 35 + 1.65 ×5 = 43.25 N/MM^2

• Target mean strength = 43.25 N/mm^2
• 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.

• 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 ).

An additional 3 % slump is increased per 25 mm slump.

• Estimated water content for 100 mm slump = 186 + 6/100 × 186 = 197 lit.
• Due to the superplasticizer 30 % water content can be reduced.

Based on the trial 29 % were achieved with plasticizers.

Hence , arrived water content 197 ×0.71 = 140 lit.

• 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 conditions is 320 kg/m^3.

Now,

• Preparing the mix containing fly ash the following steps are followed:
• Percentage of fly ash needed to be decided.
• In this design mix we increase the 10 % of cementitious material content by.

Cementious material content = 350×1.10 =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 × 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.

• Proportion of fine and coarse 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 the 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 % Therefore,
• Volume of coarse aggregate = 0.62 ×0.9 = 0.56
• Volume of fine aggregate = 1-0.56 = 0.44.
• Mix calculation :
• Volume of concrete: 1 m^3
• Volume of cement : ( mass of cement / specific gravity of cement )× ( 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 )×(1/1000).

(115/2.2)×(1/1000)= 0.052 m^3

• Volume of fly ash: 0.052 m^3
• volume of water : (mass of water / specific gravity of water ) × (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)×( 1/1000).

(7.6/1.145)×( 1/1000)= 0.006 m^3 .

• Volume of chemical admixture: 0.006 m ^3.
• 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 ×voume of coarse aggregate × specific gravity, of course, aggregate× 1000)

I.e 0.716× 0.56× 2.74×1000 = 1098 kg/m^3

• Mass of course aggregate = 1098 kg/m^3
• mass of fine aggregate: volume of aggregate × volume of fine aggregate× specific gravity of fine aggregate ×1000.

0.716×0.44×2.74×1000 = 863 kg/m^3

• Mass of fine aggregate = 863 kg /m^3
• 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
• Results :
• Trial mix ratio = 1:3.19:4.07

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

• 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: 100....... ( Slump value of pumpable concrete ).
• Exposure condition: severe for reinforced concrete.
• Method of concrete placing: pumping
• Degree of supervision: Good
• Typeof aggregate: crushed angular aggregate
• Maximum cement content : 450 kg/m^3
• Chemical admixture: superplasticizer.
• 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: Nill
• Fine aggregate: Nill
• Slive analysis: The course aggregate conforms to table 2 of IS 383 and the fine aggregate conforming to grading zone 1 of the table of IS 383.
• calculation of target mean strength for the mix :
• Standard deviations: 5 N/mm^2
• F'ck = Fck +1 .65 S

F'ck = 50+ 1.65×5 = 58.25 N/mm^2

• Target mean strength : 58 .25 N/mm^2
• 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 =

186+ (6/100)× 186 = 197 mm

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

Hence , the arrived water content : 197× 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 severe exposure conditions is 320 kg /m^3
• 350 kg/m^3 >350 kg/m^3 ........hence ok.
• 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 1 foe w/c ratio is 0.6.
• In the 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 0.10 and the proportion of the volume of coarse aggregate is increased by 0.02.
• Therefore corrected volume of coarse aggregate for the water-cement ratio of 0.40 = 0.62
• For pumpable concrete value is reduced by 10 percent
• Volume of coarse aggregate = 0.62×0.9 =0.56
• Volume of fine aggregate= 1-0.56= 0.44.
• Mix calculation :
• volume of concrete: 1 m^3
• Volume of cement : (mass of cement /specific gravity of cement )× (1/1000)

(350/3.15)×( 1/1000)= 0.111m^3

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

(140/1)×(1/1000)= 0.140 m^3

• Volume of water is 0.140 m^3
• volume of chemical admixture : ( mass of chemical admixture / specific gravity of chemical admixture )× (1/1000)

(7.6/1.145 ) × (1/1000) = 0.006m^3

• Volume of chemical admixture is 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 is 0.743 m^3
• mass of course aggregate: volume of aggregate ×volume, of course, aggregate× specific gravity of course aggregate ×1000

0.743×0.56×2.74×1000= 1140 kg /m^3

• Mass of coarse aggregate is 1140 kg/m^3
• mass of fine aggregate: volume of aggregate× volume of fine aggregate × specific gravity of fine aggregate × 1000

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

• Mass of fine aggregate is 896 kg /m^3
• 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
• Result
• Trial mix = 1: 2.56: 3.26