Water required per bag of cement (50 kg) for a standard concrete mix is approximately:
Correct Answer: C. 28 kg
📚 Detailed Explanation: Water Per Bag of Cement
Why C (28 kg) is correct: For a 1:2:4 nominal mix (M15), the typical design water-cement ratio is approximately 0.55–0.60. Taking w/c = 0.56 as the reference value:
Water = w/c × cement = 0.56 × 50 kg = 28 kg per bag
Water = w/c × cement = 0.56 × 50 kg = 28 kg per bag
w/c ratio for 1:2:4 mix ≈ 0.55–0.60
Using w/c = 0.56 (standard reference):
Using w/c = 0.56 (standard reference):
Water = 0.56 × 50 kg = 28 kg per bag
Water Requirement vs. Mix Ratio
| Nominal Mix | Approx. w/c | Water per 50 kg Bag (kg) |
|---|---|---|
| 1:3:6 (M10) | 0.65–0.70 | 33–35 kg |
| 1:2:4 (M15) | 0.55–0.60 | 28–30 kg |
| 1:1.5:3 (M20) | 0.50–0.55 | 25–28 kg |
| 1:1:2 (M25) | 0.45–0.50 | 22–25 kg |
- Standard water requirement: 28 kg per 50 kg bag of cement for 1:2:4 (M15) mix.