CURING OF CONCRETE AND RIGHT TIME OF CURING

Curing of concrete play a major role in developing the micro-structure and pore structure of concrete. Curing of concrete mean maintain moisture(HUMIDITY) inside the body of concrete during the early ages and beyond in order to develop the desired properties in terms of  durability & strength.

A good curing practiceS involves keep the concrete damp until the concrete is strong(HARD) enough to do its job. However, good curing practices are not always continently follow in most of the cases, leading to a weak concrete.

When concrete is not curing properly, its strength ,durability and abrasive resistance are affected . The poor curing has result in a permanently defective micro structure and generate cracks.

Right Time to Curing of Concrete

1. After concrete has been placed in  final position and during initial set, bleed water rises to the concrete surface as plastic settlements occurs. During this period, if the rate of evaporation of bleed water is greater than  rising water, plastic shrinkage of the concrete occur. Initial mist curing is inportant to keep the surface moist(humid) to prevent the surface from drying out it is good for concrete.
2. During initial set and final set, intermediate curing would be needed if the finishing is complete prior to final set. This may be in the form of a barrier(circle) which prevent the loss of moisture (humidity)from the concrete surface. e.g. covering the concrete surface with plastic sheets, waterproof paper, bags  .
3. After final set, meticulous curing will have to be done as per the procedures selected. e.g. water curing methods-Ponding, Misting, wet coverings with hessian cloth, Impermeable membrane curing, Curing compound etc.                                                                                                without covering surfaces of concrete shall be kept continuously damp or in a wet condition by ponding or by covering with sacks, canvas, hessian or other similar material and kept continuously wet for atleast 7 days from the date of placing, in case of Ordinary Portland Cement (OPC) and atleast 10 days when mineral admixtures or blended cements are used. In case of concrete where mineral admixtures  are used, it is recommended that the above minimum periods may be extended to 14 days, for assisting the secondary reaction.