Concrete gains strength through a chemical reaction that needs water. If the surface dries early, it cracks and stays weak.
How long
IS 456 asks for at least 7 days of curing with ordinary Portland cement, and at least 10 days where mineral admixtures or blended cements are used. In hot, dry weather, cure for at least 10 days, and consider 14 days with blended cements.
Methods
- Ponding on slabs with small mud or cement bunds.
- Wet gunny bags or jute on columns and walls.
- Curing compound where water is scarce, applied as the maker directs.
Common mistakes
- Starting too late, or curing only in the morning.
- Stopping after two or three days.
- Letting the water run off before it soaks in.
Plan curing before the pour and assign someone to do it daily.
General guidance only. Every project differs; consult your engineer for yours.