One bag of cement contains
Correct Answer: D. 50 kg
📚 Detailed Explanation: Standard Cement Bag Weight
The packaging of cement follows a standard set by the Bureau of Indian Standards. Knowing the standard bag weight is essential for on-site batching calculations, where ingredients are measured by the number of cement bags rather than by precise weight.
Why D (50 kg) is correct: IS 269, IS 8112, and IS 12269 (OPC specifications) all specify that cement shall be packed and sold in bags of 50 kg. This has been the standard for decades in India. Options 30, 40, and 45 kg are not standard bag sizes for OPC. White cement is sometimes available in 25 kg bags for retail, and Rapid-hardening cement in smaller packs, but the universal reference in concrete design and mixing is the 50 kg OPC bag.
Volume of One Bag of Cement
| Parameter | Value |
|---|---|
| Standard bag weight | 50 kg |
| Specific gravity of cement | 3.15 |
| Volume (absolute) | 50 / 3.15 = 15.87 litres |
| Bulk (loose) volume in bag | ~34.5 litres (0.035 m³) |
| Number of bags per tonne | 20 bags |
Key Concepts for Students
- 1 bag = 50 kg = 0.0347 m³ (bulk volume) — used in mix design volume calculations.
- When calculating water content: if w/c = 0.5, one bag (50 kg) needs 25 litres of water.
- Cement is measured by weight (not volume) in all standard mix designs — volume measurement is inaccurate due to bulking.