What is curing?
Curing of Concrete is a method by which the concrete is protected against loss of moisture required for hydration and also maintained within the recommended temperature level. Curing will increase the strength and reduce the permeability of hardened concrete. Curing additionally helps in reducing thermal and plastic cracks, which can badly affect the durability of structures.
A curing practice entails keeping the concrete wet or moist until the hydration of concrete is complete and strength is achieved. Curing of concrete must start right after the initial setting time of concrete and must continue for a reasonable period of time according to the defined requirements, for the concrete to achieve its desired strength and durability.
Protecting procedures are also needed to control water loss from the concrete surface area to prevent plastic shrinkage cracks. Curing of concrete is a procedure designed mainly to retain the concrete moist till the end of hydration by monitoring loss of dampness and water from the concrete surface during the specified time in which it gains strength.
Methods of Curing.
The most typical method of curing is as follows:
- Water Curing
- Membrane Curing
- Curing Compound
- Steam Curing
It is the most effective method of curing. In this method, water is used on the concrete surface for a certain duration. It’s done by spraying or sprinkling water or curing agents over the concrete surface to ensure that the concrete surface is continuously wet.
Moisture from the body of concrete is maintained from evaporating and contributes to gain the required strength of concrete. Vertical wall surfaces, columns, plastered surfaces are cured by the sprinkling of water on it. Vertical surfaces are also cured by using some wet covering such as cloth, jute matting.
Straight surfaces are kept wet by covering concrete with wet sand and jute matting etc. There are the following ways of water curing.
- Wet Covering
Where there is a shortage of water, membrane curing is adopted. Generally, water mixed for making concrete is more than sufficient to hydrate the cement.
Membranes are used all over the concrete which will properly seal the concrete. The membranes seal over the concrete by means of a firm invulnerable film to stop moisture in concrete from getting away by evaporation.
This prevention of moisture in the concrete will function as a curing of concrete.
Membrane curing methods are:
- Plastic sheeting
There are certain curing compounds that maintain the concrete damp. Calcium chloride is the one curing compound. It can be used as a surface coating.
Calcium chloride is a salt, it reveals an affinity for wetness. The salt not only absorbs the moisture from the atmosphere but also keeps it at the surface. Salt keeps the concrete damp for a long time to promote hydration.
The Curing compounds are available on various other things.
When concrete is subjected to a higher temperature level, with extra moisture it increases the hydration process and results in the higher development of strength.
The Concrete can’t go through completely dry heat due to moisture which is also an important requirement. Thus achieving this goal concrete is required to subject the steam Curing.
Steam curing maintains the surface moist and raises the temperature of concrete to speed up the rate of strength achievement. It is a process done to speed up the early hardening of concrete and also mortars by subjecting it to steam and moisture. This technique is most commonly used for precast concrete.