Project on Concrete Mix Design for various grades of Concrete

Concrete Mix Design for M35 Grade Concrete with Fly Ash

Aim:- To determine the concrete mix design for M35 Grade Concrete with Fly Ash.

Introduction of the Project:- Mix Proportioning of M35 Grade Concrete using Fly Ash as a part of replacement of OPC.

I. Stipulations for Proportioning

1. Grade of Designation :- M35
2. Type of Cement :- OPC 43 Grade conforming to IS 8112
3. Type of Mineral Admixture :- Fly Ash conforming to IS 3812 (Part I)
4. Maximum Nominal Size of Aggregate :- 20mm
5. Minimum Cement Content :- 340 kg/m3 [From Table 5 of IS 456:2000- Exposure Condition]
6. Minimum Water Cement Ratio :- 0.45 [From Table 5 of IS 456:2000- Exposure Condition]
7. Workability :- 100mm (Slump value for pumpable concrete)
8. Exposure Condition :- Very Severe (for R/f Concrete)
9. Method of Concrete Placing :- Pumping
10. Degree of Supervision :- Good
11. Type of Aggregate :- Crushed Angular Aggregate
12. Maximum Cement Content :- 450 kg/m3
13. Chemical Admixture Type :- Super Plasticizer

II. Test Data for Materials

• Cement Used :- OPC 43 Grade conforming to IS 8112
• Specific Gravity of Cement :- 3.15
• Fly Ash :- Conforming to IS 3812 (Part I)
• Specific Gravity of Fly Ash :- 2.2
• Chemical admixture :- Superplasticizer conforming to IS 9103
• Specific Gravity of:-

• Coarse Aggregate - 2.74
• Fine Aggregate - 2.74

• Water Absorption

• Coarse Aggregate - 0.5%
• Fine Aggregate - 1.0%

• Free Surface

• Coarse Aggregate - Nil
• Fine Aggregate - Nil

• Sieve Analysis

• Coarse Aggregate - Conforming to Table 2 of IS 383
• Fine Aggregate - Conforming to Grading Zone I of Table 4 of IS 383

III. Target Strength for Mix Proportioning

f'ck = fck +1.65 S

From Table 1 of IS 10262:2009, Standard Deviation S = N/mm2

Therefore, Target Strength = 35 + 1.65*5 = 43.25 N/mm2

IV. Selection of water cement ratio

From Table 5 of IS 456:2000 for very Severe Exposure Condition, Maximum water cement ratio = 0.45

Based on experience adopt water cement ratio = 0.40

= 0.40<0.45 Hence OK

V. Selection of Water Content

From Table 2 of IS 10262 : 2009

The maximum water content for 25mm to 50mm slump = 186 kg = 186 liter

{For additional slump 3% may be added for every 25mm slump}

Estimated Water Content for 100mm Slump = 186 + (6/100)*186 = 197 Ltr.

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

Based on trials water content reduction of 29% can be achieved with plasticizer.

Hence the arrived Water Content = 197*0.71 = 140 Ltr.

VI. Calculation of Cement Content

Water Cement Ratio = 0.4

Cementitious Material (Cement + Fly Ash) content = 140/0.4 = 350 kg/m3

From Table 5 of IS 456 Minimum Cement content for 'Very Severe' Exposure condition = 320 kg/m3

350>320 kg/m3, Hence OK

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

1. The percentage of flyash needs to be decided based on the 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 experiences and trials. (This e.g. is with increase of 10% cementitious material content).

Cementitious Material Content = 350*1.1 = 385 kg/m3

Water Content = 140 kg/m3

So, Water cement ratio = 140/385 = 0.364

Fly Ash @ 30% Total Cementitious = 385*30% = 115 kg/m3

Cement (OPC) = 385-115 = 270 kg/m3

Saving of Cement while using Fly Ash = 350-270 = 80 kg/m3

Fly Ash being utilized = 115 kg/m3

VII. Proportion of Volume of Coarse Aggregate and Fine Aggregate Content

From Table 3 of IS 10262 : 2009 volume of Coarse Aggregate corresponding to 20mm size aggregate and fine aggregate (Zone I) of water cement ratio of 0.5 = 0.6

In the present case the water cement ratio is 0.40

Therefore, the volume of Coarse Aggregate needs to be increased to decrease the Fine Aggregate Content.

As Water Cement Ratio is lower by 0.10, 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).

Therefore, the corrected volume of Coarse Aggregate for water cement ratio of 0.40 = 0.62

For Pumpable concrete these values are reduced by 10%

Therefore, Volume of Coarse Aggregate = 0.62*0.9 = 0.56

Volume of Fine Aggregate Content = 1-0.56 = 0.44

VIII. Mix Calculations

The mix calculation per unit volume of concrete shall be as follows:-

• Volume of Concrete = 1m3
• Volume of Cement = (Mass of Cement/Specific Gravity of Cement)*(1/1000) =(270/3.15)*(1/1000) = 0.086 m3
• Volume of Fly Ash = (Mass of Fly Ash/Specific Gravity of Fly Ash)*(1/1000) = (115/2.2)*(1/1000) = 0.052 m3
• Volume of Water = (Mass of Water/Specific Gravity of Water)*(1/1000) = (140/1)*(1/1000) = 0.140 m3
• Volume of Chemical Admixture = (Mass of Chemical Admixture/Specific Gravity of Admixture)*(1/1000) = (7.6/1.145)*(1/1000) = 0.006 m3
• Volume of Aggregate (FA & CA) = (a-(b+c+d+e)) = (1-0.086+0.052+0.140+0.006)) = 0.716 m3
• Mass of Coarse Aggregate = f x Volume of CA x Specific Gravity of CA x 1000 = 0.716*0.56*2.74*1000 = 1098 kg/m3
• Mass of fine aggregate = f x Volume of FA x Specific Gravity of FA x 1000 = 0.716*0.44*2.74*1000 = 863 kg/m3

IX. Mix Proportion for Trial Number 1

• Cement = 270 kg/m3
• Fly Ash = 115 kg/m3
• Water = 140 kg/m3
• Fine Aggregate = 863 kg/m3
• Coarse Aggregate = 1098 kg/m3
• Chemical Aggregate = 7 kg/m3
• Water Cement Ratio = 0.364

Trial Mix Ratio = 385:863:1098 = 1:2.242:2.852

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

XI. Two more trials having variation of 10% of Water Cement Ratio in clause X shall be carried out and a graph between three water cement raios and corresponding strengts shall be plotted to workout the mix proportions for the given target strength for field trials. However durability should be met.

Concrete Mix Design for M50 Grade Concrete without Fly Ash

Aim:- To determine the concrete mix design for M50 Grade Concrete without Fly Ash.

Introduction of the Project:- Mix Proportioning of M50 Grade Concrete without Fly Ash.

I. Stipulations for Proportioning

1. Grade of Designation :- M50
2. Type of Cement :- OPC 43 Grade conforming to IS 8112
3. Maximum Nominal Size of Aggregate :- 20mm
4. Minimum Cement Content :- 320 kg/m3
5. Minimum Water Cement Ratio :- 0.35
6. Workability :- 100mm
7. Exposure Condition :- Severe (for R/f Concrete)
8. Method of Concrete Placing :- Pumping
9. Degree of Supervision :- Good
10. Type of Aggregate :- Crushed Angular Aggregate
11. Maximum Cement Content :- 450 kg/m3
12. Chemical Admixture Type :- Super Plasticizer

II. 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:-

• Coarse Aggregate - 2.74
• Fine Aggregate - 2.74

• Water Absorption

• Coarse Aggregate - 0.5%
• Fine Aggregate - 1.0%

• Free Surface

• Coarse Aggregate - Nil
• Fine Aggregate - Nil

• Sieve Analysis

• Coarse Aggregate - Conforming to Table 2 of IS 383
• Fine Aggregate - Conforming to Grading Zone I of Table 4 of IS 383

III. Target Strength for Mix Proportioning

f'ck = fck +1.65 S

From Table 1 of IS 10262:2009, Standard Deviation S = N/mm2

Therefore, Target Strength = 50 + 1.65*5 = 58.25 N/mm2

IV. Selection of water cement ratio

From Table 5 of IS 456:2000 for Severe Exposure Condition, Maximum water cement ratio = 0.45

Based on experience adopt water cement ratio = 0.35

= 0.35<0.45 Hence OK

V. Selection of Water Content

From Table 2 of IS 10262 : 2009

The maximum water content for 25mm to 50mm slump = 186 kg = 186 liter

{For additional slump 3% may be added for every 25mm slump}

Estimated Water Content for 100mm Slump = 186 + (6/100)*186 = 197 Ltr.

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

Based on trials water content reduction of 20% can be achieved with Super plasticizer.

Based on trials with super plasticizer water content reduction of 27% has been achieved.

Hence the arrived Water Content = 197*0.73 = 143 Ltr.

VI. Calculation of Cement Content

Water Cement Ratio = 0.35

Cementitious Material content = 143/0.35 = 410 kg/m3

From Table 5 of IS 456 Minimum Cement content for 'Extreme' Exposure condition = 360 kg/m3

410>360 kg/m3, Hence OK

VII. Proportion of Volume of Coarse Aggregate and Fine Aggregate Content

From Table 3 of IS 10262 : 2009 volume of Coarse Aggregate corresponding to 20mm size aggregate and fine aggregate (Zone I) of water cement ratio of 0.5 = 0.62

In the present case the water cement ratio is 0.35

Therefore, the volume of Coarse Aggregate needs to be increased to decrease the Fine Aggregate Content.

As Water Cement Ratio is lower by 0.10, 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).

Therefore, the corrected volume of Coarse Aggregate for water cement ratio of 0.35 = 0.65

For Pumpable concrete these values are reduced by 10%

Therefore, Volume of Coarse Aggregate = 0.65*0.9 = 0.585

Volume of Fine Aggregate Content = 1-0.585 = 0.415

VIII. Mix Calculations

The mix calculation per unit volume of concrete shall be as follows:-

• Volume of Concrete = 1m3
• Volume of Cement = (Mass of Cement/Specific Gravity of Cement)*(1/1000) =(410/3.12)*(1/1000) = 0.131 m3
• Volume of Water = (Mass of Water/Specific Gravity of Water)*(1/1000) = (143/1)*(1/1000) = 0.143 m3
• Volume of Chemical Admixture = (Mass of Chemical Admixture/Specific Gravity of Admixture)*(1/1000) = (8.2/1.145)*(1/1000) = 0.007 m3
• Volume of Aggregate (FA & CA) = (a-(b+c+d+e)) = (1-0.131+0.143+0.007)) = 0.719 m3
• Mass of Coarse Aggregate = f x Volume of CA x Specific Gravity of CA x 1000 = 0.719*0.585*2.56*1000 = 1152.48 kg/m3
• Mass of fine aggregate = f x Volume of FA x Specific Gravity of FA x 1000 = 0.719*0.415*2.56*1000 = 763.86 kg/m3

IX. Mix Proportion for Trial Number 1

• Cement = 410 kg/m3
• Water = 143 kg/m3
• Fine Aggregate = 763.86 kg/m3
• Coarse Aggregate = 1152.48 kg/m3
• Chemical Aggregate = 7 kg/m3
• Water Cement Ratio = 0.364

Trial Mix Ratio = 410:763.86:1152.48 = 1:1.863:2.810

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

XI. Two more trials having variation of 10% of Water Cement Ratio in clause X shall be carried out and a graph between three water cement raios and corresponding strengts shall be plotted to workout the mix proportions for the given target strength for field trials. However durability should be met.