Project on Concrete Mix Design for various grades of Concrete

MIX DESIGN FOR M35 GRADE CONCRETE (WITH FLY ASH)

AIM:

Mix design for m35 grade concrete with fly ash.

PROCEDURE:

STEP 1: STIPULATION FOR PROPORTIONING

• Grade designation:M35
• Type of cement:OPC 43 grade conforming to IS 8112
• Type of mineral admixture: Fly ash conforming to IS 3812(PART-1)
• Maximum nominal size of aggregate:20mm
• Minimum cement content:320 kg/m³ (Table-5 IS456:2000 based on exposure condition)
• Maximum water-cement ratio:0.45(Table-5 IS456-2000 based on exposure condition)
• Workability:100mm slump value of pumpable concrete.
• Exposure condition: Severe (for reinforced)
• Method of concrete placing: Pumping
• Degree of supervision: Good
• Type of aggregate: Crushed angular aggregate
• Maximum cement content:450kg/m³
• Chemical admixture type: Super plasticizer.

STEP 2: TEST DATA MATERIAL

• Cement used: OPC 43 grade conforming to IS 8112
• Specific gravity of cement:3.15
• Fly ash: Conforming to IS3812(part-1)
• Specific gravity of fly ash: 2.2
• Chemical Admixture: Super plasticizer conforming IS9103
• Specific Gravity of:
  • Coarse aggregqate:2.74
  • Fine aggregate:2.74
• Water absorption:
  • Coarse aggregate:0.5%
  • Fine aggregate:1%
• Free surface moisture
  • Coarse aggregate: Nil
  • Fine aggregate: Nil
• Sieve Analysis:
  • Coarse Aggregate:

IS Sieve Size (mm)	Analysis of coarse aggregate		% of Different fraction		Remarks
	I	II	I 60%	II40%	Conforming to Table-2 of IS383
20	100	100	40	100
10	0	71.20	21.5	28.5
4.75		9.40	3.7	3.7
2.36		0

• Fine aggregate: Conforming to Grading zone I of Table-4 of IS383.

STEP 3

TO FIND TARGET MEAN STRENGTH OF MIX PROPORTIONING:

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

= 35+1.65x5

=43.25 N/mm²

STEP 4

SELECTION OF WATER-CEMENT RATIO:

Maximum w/c ratio = 0.45 (For Severe condition, from table-5 of IS 456-2000)

On Experience W/C ratio =0.4

0.4 > 0.45, Hence Ok.

STEP 5

CALCULATION OF WATER CONTENT:

Maximum water content for 20mm aggregate = 186 litres. (Table-2 of IS1026-2000) for,25mmto 50mm slump value,

For 125mm slump =186+(9/100) x186

=203 litres.

As Superplasticizer is used the water content can be reduced upto 20% and above based on trials water content reduction of 29% is achieved with plasticizer.

Hence, the arrived water content,

= 203 x 0.71 = 145 litre

STEP 6

CALCULATION OF CEMENT CONTENT:

Water-cement ratio =0.4

Cementitious material (Cement+Fly ash)

= 145/0.4

=363kg/m³

In table-5 of IS 456-2000, the cement content for severe exposure =320 kg/m³

363 kg/m³ >320 kg/m³, Hence Ok.

TO PROPORTION THE MIX CONTAINING FLY ASH THE FOLLOWING STEPS ARE SUGGESTED:

• The percentage of fly ash need to be decided based on project requirement and quality material.
• In some cases, increase in cementitious material can be warned. Increase in cementitious material content and it percentage may be based on experience and trial.

In this increased of 10% cementitious material content is considered,

Cementitious material content = 363 x 1.1

= 399.3kg/m³

Water content =145kg/m³

So, W/C ratio = 145/399.3

= 0.363

Fly Ash at 30% total cementitious material content,

= 399.3 x 30%

=119.79 kg/m³

Cement (OPC) = 399.3-119.79

= 279.51 kg/m³

Saving of cement while using fly ash =399.3 -279.51

= 120.22 kg/m³

Fly ash being utilized =119.79 kg/m³

STEP 7

PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE:

• From table-3 of IS 1026:2000, Volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (zone-1) for w/c ratio.

In present case of the water-cement ratio is 0.4

Therefore, the volume of coarse aggregate needs to be increase to decrease the fine aggregate content.

• As the w/c ratio is lowered by 0.1, 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)

Hence the corrected value of coarse aggregate of the w/c ratio = 0.64

(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 are reduced by 10%

Volume Of Coarse Concrete = 0.64 x0.9

= 0.576

Volume Of Fine Concrete = 1 - 0.576

= 0.424

STEP 8

MIX CALCULATION PER UNIT VOLUME OF CONCRETE:

Volume of concrete = 1m³

Volume of cement = (Mass of cement / Specific gravity of cement) x (1/1000)

= (279.51/3.15) x (1/1000)

= 0.087 m³

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

= (119.79/2.2) x (1/1000)

= 0.054 m³

Volume of water = (Mass of water / Specific gravity of water) x (1/1000)

= (145/1) x (1/1000)

= 0.1450 m³

Volume of chemical admixture = (Mass of admixture / Specific gravity of chemical admixture) x (1/1000)

= (7.6/1.14) x (1/1000)

= 0.006 m³

Volume of aggregate (C.A & F.A) = [1- (0.087+0.054+0.145+0.006)]

= 0.708 m³

Volume of coarse aggregate = f x volume of C.A x Specific gravity of C.A x 1000

= 0.708 x 0.576 x 2.74 x1000

= 1117.3 kg/m³

Volume of fine aggregate = f x volume of F.A x specific gravity of F.A x1000

= 0.708x 0.424 x 2.74 x 1000

= 822.52 kg/m³

STEP 9

MIX PROPORTION :

Cement = 279.51 kg/m³

Fly Ash = 119.79 kg/m³

Water = 145 kg/m³

Fine aggregate = 822.52 kg/m³

Coarse aggregate = 1117.3 kg/m³

Chemical admixture = 7 kg/m³

W/C ratio = 0.363

MIX RATIO =1 (0.7:0.3): 2.05:2.79

Here, 0.7 -cement,0.3 – fly ash, 2.05 – C.A, 2.79- F.A

STEP 10

The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump or trial. 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(step10) shall be carried out and a graph between three water water-cement ratio and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for failed trials. However, durability shall be met.

RESULD:

The mix design for M35 grade of concrete with fly ash is 1 (0.7:0.3): 2.05:2.79 (NOTE: Here, 0.7 -cement,0.3 – fly ash, 2.05 – C.A, 2.79- F.A)

MIX DESIGN FOR M50 GRADE CONCRETE (WITH OUT FLY ASH)

AIM:

Mix design for m50 grade concrete without fly ash.

PROCEDURE:

STEP 1: STIPULATION FOR PROPORTIONING:

• Grade designation:M50
• Type of cement:OPC 43 grade conforming to IS 8112
• Maximum nominal size of aggregate:20mm
• Minimum cement content:320 kg/m³ (Table-5 IS456:2000 based on exposure condition)
• Maximum water-cement ratio:0.45 (Table-5 IS456-2000 based on exposure condition)
• Workability:100mm slump value of pumpable concrete.
• Exposure condition: Severe (for reinforced)
• Method of concrete placing: Pumping
• Degree of supervision: Good
• Type of aggregate: Crushed angular aggregate
• Maximum cement content:450kg/m³
• Chemical admixture type: Super plasticizer.

STEP 2: TEST DATA MATERIAL:

• Cement used: OPC 43 grade conforming to IS 8112
• Specific gravity of cement:3.15
• Chemical Admixture: Super plasticizer conforming IS9103
• Specific Gravity of:
  • Coarse aggregqate:2.74
  • Fine aggregate:2.74
• Water absorption:
  • Coarse aggregate:0.5%
  • Fine aggregate:1%
• Free surface moisture
  • Coarse aggregate: Nil
  • Fine aggregate: Nil
• Sieve Analysis:
  • Coarse Aggregate:

IS Sieve Size (mm)	Analysis of coarse aggregate		% of Different fraction		Remarks
	I	II	I 60%	II40%	Conforming to Table-2 of IS383
20	100	100	40	100
10	0	71.20	21.5	28.5
4.75		9.40	3.7	3.7
2.36		0

• Fine aggregate: Conforming to Grading zone I of Table-4 of IS383.

STEP 3

TO FIND TARGET MEAN STRENGTH OF MIX PROPORTIONING:

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

= 50+1.65x5

=58.25 N/mm²

Fck = Characteristic strength

S = Standard deviation

STEP 4

SELECTION OF WATER-CEMENT RATIO:

from table-5 of IS 456-2000, by exposure condition

Here, Severe condition is considered,

Maximum water-cement ratio = 0.45

Based On Experience W/C ratio =0.4

0.4 <0.45, Hence Ok.

STEP 5

CALCULATION OF WATER CONTENT:

Maximum water content for 20mm aggregate = 186 litres.

. (Table-2 of IS1026-2000) for,25mmto 50mm slump value,

For 100mm slump =186+(6/100) x186

=197 litres.

As Superplasticizer is used, the water content is reduced upto 30%

Based on trials water content reduction of 23% is achived with plasticizer.

Hence arrived water content = 197 x 0.77

= 151.69 litres

STEP 6

CALCULATION OF CEMENT CONTENT:

Water-cement ratio =0.4

= 151.69/0.4

=379.225kg/m³

In table-5 of IS 456-2000, the cement content for severe exposure =320 kg/m³

379.225 kg/m³ >320 kg/m³, Hence Ok.

STEP 6

PROPORTION OF VOLUME OF COARSE AGGREGATE AND FINE AGGREGATE:

• From table-3 of IS 1026:2000, Volume of coarse aggregate corresponding to 20mm size aggregate and fine aggregate (zone-1) for w/c ratio.

In present case of the water-cement ratio is 0.4

Therefore, the volume of coarse aggregate needs to be increase to decrease the fine aggregate content.

• As the w/c ratio is lowered by 0.1, 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)

Hence the corrected value of coarse aggregate of the w/c ratio = 0.64

(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 are reduced by 10%

Volume Of Coarse Concrete = 0.64 x0.9

= 0.576

Volume Of Fine Concrete = 1 - 0.576

= 0.424

STEP 8

MIX CALCULATION PER UNIT VOLUME OF CONCRETE:

Volume of concrete = 1m³

Volume of cement = (Mass of cement / Specific gravity of cement) x (1/1000)

= (379.225/3.15) x (1/1000)

= 0.12 m³

Volume of water = (Mass of water / Specific gravity of water) x (1/1000)

= (151.69/1) x (1/1000)

= 0.151m³

Volume of chemical admixture = (Mass of admixture / Specific gravity of chemical admixture) x (1/1000)

= (7.6/1.145) x (1/1000)

= 0.006 m³

Volume of aggregate (C.A & F.A) = [1- (0.12+0.151+0.006)]

= 0.723m³

Volume of coarse aggregate = e x volume of C.A x Specific gravity of C.A x 1000

= 0.723 x 0.576 x 2.74 x1000

= 1145.23 kg/m³

Volume of fine aggregate = e x volume of F.A x specific gravity of F.A x1000

= 0.723 x 0.424 x 2.74 x 1000

= 839.95kg/m3

STEP 9

MIX PROPORTION :

Cement = 379.225 kg/m³

Water = 151.69 kg/m³

Fine aggregate = 839.95 kg/m³

Coarse aggregate = 1145.23 kg/m³

Chemical admixture = 8 kg/m³

W/C ratio = 0.4

MIX RATIO = 1: 2.21: 3.01 (NOTE Cement: F.A: C.A)

STEP 10

The slump shall be measured and the water content and dosage of admixture shall be adjusted for achieving the required slump or trial. 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(step10) shall be carried out and a graph between three water water-cement ratio and corresponding strengths shall be plotted to work out the mix proportions for the given target strength for failed trials. However, durability shall be met.

RESULD:

The mix design for M50 grade of concrete without fly ash is 1: 2.46: 3.35 (NOTE Cement: F.A: C.A)