Curing:

The process of hardening the concrete mixes by keeping its surface moist for a certain period after compaction is called curing of concrete. It is one of the important factors for obtaining better strength. Curing must be organized immediately after concrete is placed and compacted.

The concrete hardens because of hydration, i.e. a chemical reaction among water and portland cement. The chemical actions, which accompany the setting of concrete, are dependent on the presence of water. While there is sufficient water at the time of mixing yet it is necessary to ensure that the water is retained to enable the chemical action to continue till the concrete is fully hardened. Properties of concrete like as water-tightness, strength, durability, wear resistance and volume stability improve with the passage of time. Three gallons of water are required approximately to hydrate one bag of cement.

If the loss due to evaporation is more from newly placed concrete, a hydration procedure will stop and concrete will shrink thus creating tensile stresses at the drying surface. A development of these stresses will result within the formation of plastic shrinkage cracks.

Thus, curing is important. It improves properties of concrete such as water- tightness, wear resistance, strength, volume stability and durability.

Methods of Curing

(a)        Water curing

(b)       Membrane curing

(c)        Application of heat

(d)       Miscellaneous