After concrete is placed, a satisfactory moisture content and temperature (between 50°F and 75°F) must be maintained, a process called curing. Adequate curing is vital to quality concrete.

Curing has a strong influence on the properties of hardened concrete such as durability, strength, watertightness, abrasion resistance, volume stability, and resistance to freezing and thawing and deicer salts. Exposed slab surfaces are especially sensitive to curing. Surface strength development can be reduced significantly when curing is defective.

Curing the concrete aids the chemical reaction called hydration. Most freshly mixed concrete contains considerably more water than is required for complete hydration of the cement; however, any appreciable loss of water by evaporation or otherwise will delay or prevent hydration. If temperatures are favorable, hydration is relatively rapid the first few days after concrete is placed; retaining water during this period is important. Good curing means evaporation should be prevented or reduced.

Curing methods:

Liquid membrane-forming compounds sprayed onto the surface are effective, economical moisture barriers for moist-curing concrete.	Polyethylene sheets are effective, economical moisture barriers for moist-curing concrete.
Burlap kept saturated with water is an effective medium for moist-curing concrete.	Straw or hay is still used to insulate fresh concrete in freezing weather.

 
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