Concrete Curing is the process of controlling the rate and extent of moisture loss from concrete during cement hydration. The hardening is not due to drying. If concrete is allowed to dry soon, it results in poor strength and a porous material is obtained.
It may be either after it has been placed in position (or during the manufacture of concrete products), thereby providing time for the hydration of the cement to occur. Since the hydration of cement does take time – days, and even weeks rather than hours – curing must be undertaken for a reasonable period of time if the concrete is to achieve its potential strength and durability. Curing may also encompass the control of temperature since this affects the rate at which cement hydrates.
The curing period may depend on the properties required of the concrete, the purpose for which it is to be used, and the ambient conditions, ie the temperature and relative humidity of the surrounding atmosphere.
Curing is designed primarily to keep the concrete moist, by preventing the loss of moisture from the concrete during the period in which it is gaining strength. Curing may be applied in a number of ways and the most appropriate means of curing may be dictated by the site or the construction method.Various methods of curing are designed to maintain continuously concrete in the moist condition for several days, either by preventing evaporation or by keeping the surface of the concrete continuously wet.
Physical barriers to prevent evaporation
- Leaving forms in place
- Polyethylene sheets/tarps
- Curing papers
- Saturated burlap
- Fog Spray
Membrane Curing Compounds
- Synthetic resin (plastic) base
- Wax base
- Wax and synthetic resin base
- Acrylic polymers in water base
Advantages of Concrete Curing Compound
- Easy to apply
- Cost effective
- No need for continuous monitoring or application as would be required for fog-spray systems or wetting burlap
- Minimal equipment requirements and costs
- No debris or tarps to reuse and store
Essential Properties of a Concrete Curing Compound
- Forms an impervious film on concrete
- Free of pinholes
- Strongly adheres to surface of concrete
- Prevents the concrete mixing water from evaporating