| Primary value | 7 days (OPC) (PPC: 14 days · PSC: 14 days) |
| Applies to | Normal RCC slabs, beams and columns in mild / moderate exposure · Site-mixed and ready-mix concrete using OPC 43 / 53 grade · Plastering and brick-masonry curing of cement bands |
| Exceptions | OPC concrete (mild/moderate exposure) → 7 days |
| PPC, PSC and blended cements → 14 days | |
| Severe / very severe / extreme exposure → Increase by 50% (≥ 10 / 21 days) | |
| Hot weather (≥ 40 °C ambient) → Continuous wet-cover for at least 10 days | |
| Mass concrete (raft, dam) → 21 + days, temperature-controlled | |
| Measured as | Continuous wet curing — ponding, gunny-bag soaking, fogging or curing compound — counted from the first day after final set. Period extends if water source is interrupted. |
| Source | IS 456 — Clause 13.5 ✓ Verified |
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Curing is the cheapest strength-control measure on site and the most-skipped one. OPC reaches ~70% of 28-day strength in 7 days under wet conditions — interrupting cure earlier costs 15–25% strength permanently. PPC and slag cements hydrate slower and need 14 days to reach the same milestone, which is why the IS 456 number doubles for blended binders.
Organised sites pond slabs from day 2 to day 7 (OPC) or day 14 (PPC). Smaller jobs use gunny-bag wrap on columns and beams, hand-watered 2–3 times a day. Curing compounds are increasingly used for vertical members where water-retention is impractical.