The process of hardening concrete by keeping its surface moist is known as:
Correct Answer: C. Curing
📚 Detailed Explanation: Curing — Keeping Concrete Moist for Hardening
Why C (Curing) is correct: Keeping the concrete surface moist so that hydration can continue and the concrete can reach its design strength is precisely the definition of curing. This is a deliberate, controlled process governed by IS 456 minimum duration requirements.
Distinguishing Similar Terms
| Term | Definition | IS Reference |
|---|---|---|
| Placing | Depositing fresh concrete in formwork at the correct location | IS 456 Cl. 13 |
| Wetting | General application of water (not a technical concrete term) | — |
| Curing | Maintaining moisture and temperature for concrete to develop design strength | IS 456 Cl. 13.5 |
| Compacting | Removing entrapped air to densify fresh concrete | IS 456 Cl. 13.3 |
Minimum Curing Durations (IS 456:2000)
| Condition | Minimum Curing Period |
|---|---|
| OPC concrete (M20 and below) | 7 days |
| OPC concrete (above M20) | 14 days |
| Blended cement (PPC/PSC) | 14–28 days |
| Hot weather (>40°C) | Up to 28 days |
- Curing = process of keeping concrete moist for hardening and full strength development.
- Start curing within 10 hours of placement to prevent early surface drying.
- Minimum 7 days for OPC (IS 456); longer for blended cements and hot weather.