Guide to Absolute Volume Method in Concrete Mix Design (With Example)

Concrete mix design is a fundamental process in civil engineering that determines the correct proportions of materials (cement, water, fine aggregate, coarse aggregate, and admixtures) to achieve the desired strength and durability. 

Among several methods available, the Absolute Volume Method is one of the most widely used, especially for precise design calculations. This method is emphasized in codes such as IS 10262:2019 (Indian Standard) and ACI 211.1 (American Concrete Institute).

What is the Absolute Volume Method?

The Absolute Volume Method is based on the principle that the total volume of concrete equals the sum of the absolute volumes of its ingredients, including entrapped air. Each material has its own density (specific gravity), and using this, we can calculate the volume it will occupy in a unit volume (typically 1 m³) of concrete.

Step-by-Step Procedure (As per IS 10262:2019)

1.       Step 1: Target Strength for Mix Proportioning

fck' = fck + 1.65 × S

Read More On: Target Mean Strength of Concrete

2.       Step 2: Selection of Water-Cement Ratio

Based on target strength and durability requirements.

3.       Step 3: Selection of Water Content and Fine Aggregate Proportion

Refer to IS 10262:2019 Table 4 (for 20 mm maximum aggregate).

4.       Step 4: Calculation of Cement Content

Cement = Water / Water-Cement Ratio

5.       Step 5: Volume of Concrete

Assumed as 1 m³

6.       Step 6: Volume of Entrapped Air

Typically 2% = 0.02 m³

7.       Step 7: Volume of Admixture

Volume = Mass / (Specific Gravity × 1000)

8.       Step 8: Calculation of Volume of Cement, Water, and Admixture

Volume = Mass / (Specific Gravity × 1000)

9.       Step 9: Volume of Aggregates

Volume = 1 - (Volume of cement + water + admixture + air)

10.   Step 10: Mass of Aggregates

Mass = Volume × Specific Gravity × 1000

Example Problem: Design M30 Concrete Using Absolute Volume Method

Given:

- Grade: M30
- Target Strength: fck = 30 MPa
- Standard Deviation: S = 5.0 MPa
- Max. Aggregate Size: 20 mm
- Workability: 75 mm slump
- Cement SG = 3.15
- Coarse Aggregate SG = 2.7
- Fine Aggregate SG = 2.65
- Water SG = 1.0
- Admixture SG = 1.145 (1% by weight of cement)
- Sand Zone: II
- Exposure: Moderate

Step-by-step calculation with results:

• Step 1: Target Strength - fck' = 30 + 1.65 × 5 = 38.25 MPa
• Step 2: Water-Cement Ratio - Use 0.4
• Step 3: Water Content - 186 kg/m³
• Step 4: Cement Content - Cement = 186 / 0.4 = 465 kg/m³
• Step 5: Volume of Concrete - 1 m³
• Step 6: Entrapped Air - 0.02 m³
• Step 7: Volume of Cement - 465 / (3.15 × 1000) = 0.1476 m³
• Step 8: Volume of Water - 186 / (1 × 1000) = 0.186 m³
• Step 9: Volume of Admixture - 4.65 / (1.145 × 1000) = 0.00406 m³
• Step 10: Volume of Aggregates - 1 - (0.1476 + 0.186 + 0.00406 + 0.02) = 0.64234 m³
• Split: CA = 60%, FA = 40% - CA: 0.3854 m³, FA: 0.2569 m³
• Mass of CA - 0.3854 × 2.7 × 1000 = 1040.6 kg
• Mass of FA - 0.2569 × 2.65 × 1000 = 681.8 kg

Final Mix Proportion (by weight)

Cement: 465 kg
Water: 186 kg
FA: 682 kg
CA: 1041 kg
Admixture: 4.65 kg

Mix Ratio (approx): 1 : 1.47 : 2.24 : 0.4 (Cement : FA : CA : W/C)

Read On: Factors Affecting of Choice of Mix Proportions

Conclusion

The Absolute Volume Method provides a precise and scientifically grounded approach to concrete mix design. It ensures optimum usage of materials, better quality control, and reliability in structural performance. Understanding and practicing this method is essential for every civil engineer involved in concrete construction.

Read More On: Different Concrete Mix Design Methods