Project on Concrete Mix Design for various grades of Concrete

*Calculate the Concrete Mix Design for M35 grade concrete with fly ash.

AIM:

• To calculate the concrete mix design for M35 grade concrete with fly ash.

OBJECTIVE:

• The main objective is to produce concrete as economically as possible.
• To achieve desired workability, durability and minimum strength of M35 grade of concrete

EQUATION:

• Trget mean strenghth of concrete(f'ck)

f_target = f_ck + 1.65 x s

Explanation of the terms

‘f_target‘ is the Target Average Compressive Strength at 28 days,

‘fck’ is the Characteristic Compressive Strength at 28 days, and

‘s’ is the Standard Deviation

• Volume of concrete = 1m³
• Volume of cement = (Mass of Cement/Specific Gravity of Cement) X (1/1000)
• Volume of fly ash = (Mass of Fly ash/Specific Gravity of Fly ash) X (1/1000)
• Volume of water = (Mass of Water/Specific Gravity of Water) X (1/1000)
• Volume of superplasticizer = (Mass of Superplasticizer / Specific Gravity of Admixture) X (1/1000)
• Volume of all aggregate = (Volume of concrete -(Volume of cement + Volume of fly ash + Volume of water + Volume of superplasticizer))
• Mass of coarse aggregate = Volume of all Aggregate X Volume of coarse Aggregate X Specific Gravity of Coarse Aggregate X 1000
• Mass of fine aggregate = Volume of all Aggregate X Volume of Fine Aggregate X Specific Gravity of Fine Aggregate X 1000

Stipulations for Mix Design Concrete

• Grade designation : M 35
• Type of cement : OPC 43 grade confirming to IS 8112
• Maximum nominal size of aggregate : 20 mm
• Minimum cement content : 360 kg/m³
• Maximum water-cement ratio : 0.40
• Workability : 50-100 mm (slump)
• 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/m³
• Chemical admixture type : Super Plasticizer

Test data for material

• Specific gravity of cement : 3.15
• Specific gravity of Fly ash : 3.15
• Specific gravity of Coarse aggregate : 2.74
• Specific gravity of Fine aggregate : 2.65
• Specific gravity of water : 3.15
• Water absorption by coarse aggregate : 0.5%
• Water absorption by coarse aggregate : 1.0%

Sieve Analysis

PROCEDURE AND CALCULATION 1.Target mean strength

f_target = f_ck + 1.65 x s

For M35, fck= 35 N/mm2

as per the table I of IS: 10262-2009 , the standard deviation, s is 5.0 N/mm²

Therefore, target strength = 35 + 1.65 x 5.0 = 43.25 N/mm² 2.Selection of Water/Cement Ratio

From Table 5 of IS 456:2000,

For severe condition, W/C ratio=0.45

On experience, W/C ratio=0.40

Lower the water cement ratio better the workability

0.40<0.45, hence ok.

Water cement ratio = 0.40 3. Selection of Water Content

From Table 2 of IS 456:2000, maximum water content =186 litres (for 25 to 50 mm slump range) for 20 mm aggregate.

Clause 4.2 suggests that for increasing of 3% of water content for every extra 25mm slump from 50mm slump.

Estimated water content for 100 mm slump =186+(6/100) x 186 =197 litres.

(Note: If Super plasticizer is used, the water content can be reduced upto 20% and above.)

Based on trials with Super plasticizer, water content reduction of 20% has been achieved.

Hence the arrived water content = 197-[197 x (20/100)] = 138 litres. 4. Calculation of Cementitious Content

Water-cement ratio =0.40

Total Cementitious (cement + fly ash) requirment ( water content / water cement ratio) = 138/0.40 = 345 kg/m³

From Table 5 of IS 456:2000, minimum cement content for ‘SEVERE’ exposure condition = 320 kg/m³

345 kg/m³ > 320 kg/m³, hence, O.K.

Now to proportion a mix containing Fly Ash the following steps are adopted.

# The percentage of Fly Ash needs to be decided based on project requirement and quality of materials.

# In some cases increase in cemetitious material can be warranted.

Increase in cementitous material content and its percentage may be based on experience andtrial.

In this cementitious material increase by 10%

Cementitious material content = ((345/100)x 10)+ 345 = 380 kg/m3

Water content = 138 kg/m3

So water cement ratio = 138/380 = 0.363

Fly Ash @ 30% total cementitious material content = (380/100)x30 = 114 kg/m3

Cement (OPC) = 380 - 114 = 266 kg/m3

Saving of cement by using fly ash = 345 - 266 = 79 kg/m3

Fly Ash being utilized = 114 kg/m3

5. The Proportion of the Volume of Coarse Aggregate and Fine Aggregate Content

From Table 3 of IS 10262:2009, the volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone I) for a water-cement ratio of 0.50 =0.62.

In the present case, the water-cement ratio is 0.40.

Therefore. the volume of coarse aggregate is required to be increased to decrease the fine aggregate content.

As the water-cement ratio is lower by 0.10.

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 the water-cement ratio).

Therefore. the corrected proportion of the volume of coarse aggregate for the water-cement ratio of 0.40 = 0.62.

NOTE – In case the coarse aggregate is not angular one. then also the volume of coarse aggregate may be required 10 be increased suitably, based on experience.

For pumpable concrete, these values should be reduced by 10 percent.

Therefore, volume of coarse aggregate = 0.62 x 0.9 = 0.56.

Volume of fine aggregate content =1 – 0.56 =0.44 6. Mix Calculations

a) Volume of concrete = 1m³

b) Volume of cement = (Mass of Cement/Specific Gravity of Cement) X (1/1000)

= (266/3.15) X (1/1000)

= 0.09 m³

c) Volume of Fly Ash = (Mass of Fly Ash / Specific gravity of Fly Ash) x (1/1000)

=(114/2.2) x (1/1000)

=0.0518 m³

d) Volume of water = (Mass of Water/Specific Gravity of Water) X (1/1000)

= (147/1) X (1/1000)

= 0.147 m³

e) Volume of superplasticizer = (Mass of Superplasticizer / Specific Gravity of Admixture) X (1/1000)

= (8.2/1.145) X (1/1000)

= 0.007 m³

f) Volume of all aggregate = (a-(b+c+d+e))

= 1 – (0.09 + 0.0518+0.147+0.007)

= 0.704 m³

g) Mass of coarse aggregate = Volume of all Aggregate X Volume of coarse Aggregate X Specific Gravity of Coarse Aggregate X 1000

= 0.704 x 0.56 x 2.74 x 1000

= 1080.22 kg

h) Mass of fine aggregate = Volume of all Aggregate X Volume of Fine Aggregate X Specific Gravity of Fine Aggregate X 1000

= 0.704 x 0.44 x 2.65 x 1000

= 848.75 kg 7. Concrete Mix Proportions

• Cement = 266 kg/m³
• Fly Ash= 114 kg/m³
• Water = 138 kg/m³
• Super plasticizer = 7 kg/m³
• Fine aggregates = 848.75 kg/m³
• Coarse aggregate = 1080.22 kg/m³
• W/c = 0.363 Final Concrete Mix Ratio

Mix ratio of M45 is 1 : 3.19 : 4.06 (Cement : Fine aggregate : Coarse aggregate).

*Calculate the Concrete Mix Design for M50 grade concrete.

AIM:

• To calculate the concrete mix design for M50 grade concrete with fly ash.

OBJECTIVE:

• The main objective is to produce concrete as economically as possible.
• To achieve desired workability, durability and minimum strength of M35 grade of concrete

EQUATION:

• Trget mean strenghth of concrete(f'ck)

f_target = f_ck + 1.65 x s

Explanation of the terms

‘f_target‘ is the Target Average Compressive Strength at 28 days,

‘fck’ is the Characteristic Compressive Strength at 28 days, and

‘s’ is the Standard Deviation

• Volume of concrete = 1m³
• Volume of cement = (Mass of Cement/Specific Gravity of Cement) X (1/1000)
• Volume of water = (Mass of Water/Specific Gravity of Water) X (1/1000)
• Volume of superplasticizer = (Mass of Superplasticizer / Specific Gravity of Admixture) X (1/1000)
• Volume of all aggregate = (Volume of concrete -(Volume of cement + Volume of fly ash + Volume of water + Volume of superplasticizer))
• Mass of coarse aggregate = Volume of all Aggregate X Volume of coarse Aggregate X Specific Gravity of Coarse Aggregate X 1000
• Mass of fine aggregate = Volume of all Aggregate X Volume of Fine Aggregate X Specific Gravity of Fine Aggregate X 1000

Stipulations for Concrete Mix Design

• Grade designation : M 50
• Type of cement : OPC 53 grade confirming to IS 8112
• Maximum nominal size of aggregate : 20 mm
• Minimum cement content : 360 kg/m³
• Maximum water-cement ratio : 0.35
• Workability : 50-75 mm (slump)
• Exposure condition : Extreme (for reinforced concrete)
• Method of concrete placing : Pumping
• Degree of supervision : Good
• Type of aggregate : Crushed angular aggregate
• Maximum cement content : 450 kg/m³
• Chemical admixture type : Super Plasticizer

Test Data for Materials

• The following data are collected by performing standard tests in a laboratory.
• Specific gravity of cement : 3.12
• Specific gravity of Coarse Aggregate : 2.74
• Specific gravity of Fine Aggregate : 2.56

Sieve Analysis

Procedure for Concrete Mix Design of M 50 Concrete

1. Target Strength for Mix Proportioning

f_target = f_ck + 1.65 x s

f_target denotes the Target Average Compressive Strength at 28 days,

f_ck denotes the Characteristic Compressive Strength at 28 days,

‘s’ stands for Standard Deviation

According to the table 1 of IS: 10262-2009 ,

standard deviation, s = 5.0 N/mm²

Therefore, target strength = 50 + 1.65 x 5.0 = 58.25 N/mm²

2. Selection of Water/Cement Ratio

From Table 5 of IS 456 : 2000,

Maximum water-cement ratio = 0.35

3. Selection of Water Content

From Table 2 of IS 456, maximum water content =186 litres (for 25 to 50 mm slump range) for 20 mm aggregate.

Estimated water content for 100 mm slump =186+(6/100) x 186 =197 litres.

(Note: If Super plasticizer is used, the water content can be reduced up to 20% and above.)

Based on trials with Super plasticizer water content reduction of 27% has been achieved, Hence the arrived water content = 197 – [197 x (27/100)] = 143 litres.

4. Calculation of Cement Content

Water-cement ratio = 0.35

Cement content = 143/0.35 = 410 kg/m³

From Table 5 of IS 456, minimum cement content for ‘Extreme exposure’ condition = 360 kg/m³

410 kg/m³ > 360 kg/m³, hence, O.K.

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

From Table 3 of IS 10262. volume of coarse aggregate corresponding to 20 mm size aggregate and fine aggregate (Zone II) for a water-cement ratio of 0.50 =0.62.

In the present case, the water-cement ratio is 0.35. Therefore. the volume of coarse aggregate is required to be increased to decrease the fine aggregate content.

As the water-cement ratio is lower by 0.10. 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 the water-cement ratio).

Therefore. the corrected proportion of the volume of coarse aggregate for the water-cement ratio of 0.35 = 0.65.

NOTE – In case the coarse aggregate is not angular one, then the volume of coarse aggregate may be increased by 10 percent based on experience.

For pumpable concrete, these values should be reduced by 10 percent.

Therefore, volume of coarse aggregate = 0.65 x 0.9 = 0.585.

Volume of fine aggregate content =1 – 0.585 =0.415

6. Mix Calculations

a) Volume of concrete = 1m³

b) Volume of cement = (Mass of Cement/ Its Specific Gravity ) X (1/1000)

= (410/3.12) X (1/1000)

= 0.131 m³

c) Volume of Water = (Mass of water/specific gravity of water) X (1/1000)

= (143/1) X (1/1000)

= 0.143 m³

d) Volume of Superplasticizer = (Mass of Superplasticizer / Specific gravity of admixture) X (1/1000)

= (8.2/1.145) X (1/1000)

= 0.007 m³

e) Volume of all aggregate = (a – (b + c + d))

= 1 – (0.131 + 0.143+0.007)

= 0.719 m³

e) Mass of coarse aggregate = Volume of All Aggregate X Volume of Coarse Aggregate X Specific Gravity of Coarse Aggregate X 1000

= 0.719 x 0.585 x 2.74 x 1000

= 1152.48 kg

f) Mass of fine aggregate = Volume of all aggregate X volume of fine aggregate X Specific gravity of fine aggregate X 1000

= 0.719 x 0.415 x 2.56 x 1000

= 763.86 kg

7. Concrete Mix Proportions

• Cement = 410 kg/m³
• Water = 143 kg/m³
• Super plasticizer = 7 kg/m³
• Fine aggregates = 763.86 kg/m³
• Coarse aggregate = 1152.48 kg/m³
• W/c = 0.35

Mix ratio of M45 is 1 : 1.86 : 2.81 (Cement : Fine aggregate : Coarse aggregate).