ACI 308R
Guide to External Curing of Concrete
Curing: keeping enough moisture and a suitable temperature in fresh concrete long enough for the cement to keep hydrating and the surface to develop its properties.
Who needs it
Every contractor placing concrete, plus inspectors and specifiers, since curing is the most commonly skipped step with the most predictable consequences.
What the test involves
It covers the available curing methods — ponding and continuous wetting, wet coverings, plastic sheeting, and membrane-forming curing compounds — along with when each is appropriate and how long curing should continue based on the mix and the exposure. It emphasizes that curing begins as soon as the surface is at risk of drying, which for flatwork can be before finishing is complete. It also addresses curing's role in surface durability, since the top layer dries first and is the part that dusts, scales, and wears.
Common misconceptions
- Curing is not drying. Concrete needs to stay moist to gain strength, and 'letting it dry out' is the opposite of what the material requires.
- Sprinkling a slab intermittently is worse than not wetting it at all, because repeated wetting and drying cycles the surface and can cause crazing.
- The bottom of a slab can be perfectly cured while the top few millimeters — the part that takes all the traffic — were never cured at all.
Official source
We summarize scope and purpose only. The full text belongs to the issuing body — read it at the official source. American Concrete Institute