Curing is the process of controlling moisture loss from concrete that has already been placed. Curing ensures hydration of the cement, which in turn enhances its, strength and durability. Curing takes place immediately after placing of the concrete and deals with maintenance of the desired temperature and moisture for extended periods of time.
The length of curing time depends upon many factors such as the weather conditions, the size and shape of the concrete member, mixture proportions and strength of the mixture.
There are three primary ways in which curing of concrete can be achieved, they are:
- Maintaining mixing water in concrete during the early hardening process.
- Reducing the loss of mixing water from the surface of the concrete.
- Accelerating strength gain using heat and additional moisture.
The chemical reactions between cement & water produces C-S-H gel which bonds the ingredients of concrete, viz. coarse & fine aggregates, mineral admixtures, etc, and converts these fragments into a rock solid mass. This is possible only if continuous curing is done for at least 14 days; irrespective of the type of cement used. It is understood that blended cements require prolonged curing to convert calcium hydroxide into C-S-H gel. However, in case of OPC as well, voids within the concrete mass are filled up and disconnected by the formation of C-S-H gel after about 10 days of curing.
To have a dense microstructure and impermeability, prolonged curing is a must which leads to enhanced durability. Well-designed concrete may give poor durability if not properly cured and on the other hand a moderately designed concrete if well cured can give a better durability. Hence importance of curing should never be ignored.
Curing has a strong influence on all properties of concrete and therefore it should not be taken lightly. Properly cured concrete has better surface hardness and can better withstand surface wear and abrasion.
Curing also makes concrete more impermeable, which prevents moisture and water-borne chemicals from entering into the concrete, thereby increasing durability and service life.
Proper curing helps to prevent grazing, dusting, surface disintegration and scaling. Adequate curing reduces shrinkage, gives better resistance to wear and improves long-term appearance.
Without proper curing, the chemical process of hydration is not complete. You will never be able to get the designed strength of concrete and please note that this is a loss of strength for a lifetime and there is no easy alternative to strengthen such poorly cured weak concrete. So always be careful and cure with care.
When picking cement, you want to go with the best choice for your project at hand. There are variety of offers with range of specialized cements which are high-strength, durable and work best for any and all kind of projects. They are ideal for all kinds of constructions, from flyovers to underwater concrete work to dams & canals. Invest well, build strong!