Importance of curing and its methods for different components of house

What is curing?

In any building construction which involves the usage of cement as a building product in any component of the building, it is an absolutely necessary process to keep the freshly placed concrete or mortar moist. The method of keeping the cement moist in order to maintain a commensurate natural temperature between the concrete and the immediate environment, in order to develop the desired properties of concrete or mortar in terms of strength & durability is curing.

Why curing is important?

As the concrete is placed, it starts to get in the hard state. The reaction between cement and water starts from when the water is first added to the dry concrete mix. This reaction is called hydration and it releases heat. Thus the water starts evaporating, once water evaporates from the surface of concrete, the hydration process slow down or it stops. It may result in development of cracks or reduces the strength and durability of concrete. Curing helps to decrease the heat of hydration produced in concrete which leads to the formation of cracks. It helps in securing bonding structure of the concrete.

  • To prevent the concrete to dry out prematurely due to solar radiation and wind. This prevents plastic shrinkage of concrete.
  • It helps to maintain the concrete temperature by allowing the hydration process. Hydration process requires water to carry on and releases heat.
  • Curing helps the concrete to harden and bond with internal materials and reinforcement. This helps to prevent damage to bond between concrete and reinforcement due to vibration and impact.
  • This helps development of impermeable, crack free and durable concrete.
Methods of curing

  1. Spraying

    Curing by spraying of water or fogging is one of the conventional and most commonly used methods of curing concrete in the construction industry which is carried out by sprinkling/spraying water on the surface of concrete for 2 or more coats by using pipe, nozzles or sprayers.

  2. Gunny bags

    Water absorbent fabrics are used to maintain moisture on the concrete surface by completely covering the surface immediately after the concrete has hardened sufficiently. One such material is gunny bags which have greater capacity of holding water for longer time period. So wet gunny bags are placed on the surface of concrete and left for some period of time till these gunny bags become dry. Gunny bags are mostly used for curing of non-flat surfaces. They must be continuously kept wet to prevent the fabric from absorbing water from the body of concrete, due to capillary action. Generally jute bags, cotton mats, hussian cloth, etc. are used as a covering.

  3. Ponding

    This method is usually carried out for slab curing. Boundaries or small rectangular artificial ponds are formed with mortar on all the side of slab for thickness of about 4cm to 5cm and water is made to store on the slab in the form of pond two or three times per day depending upon the atmospheric conditions. This method is very efficient but the amount of water required is huge Methods like membrane curing and steam curing are also considered as different methods of curing, but they are not much used practically.
Duration of curing for various components
As per IS 456 -2000, the curing duration of concrete according of various conditions are given below
  • Concrete with ordinary Portland cement – Min 7 days
  • Concrete with mineral admixtures or blended cement – Min 10 days
  • Concrete exposed to extreme dry and hot weather conditions using OPC– Min 10 days
  • Concrete exposed to extreme dry and hot weather conditions using mineral admixtures or blended cement – Min 10 days
  • For brick work curing should be commenced within 12 hours.
    • In case of cement sand mortar – Min 7 days
    • In case of rich mortar 1:4 and more- 10 days.
  • Water curing the existing wall before plaster is required just once immediately before commencement of plaster. It is done to ensure that the existing wall does not absorb water from cement paste (mortar) that is used for plaster
  • Finished brickwork in lime mortar should be cured for a period of 2 to 3 weeks. This period can be reduced to 1 to 2 weeks in case of brickwork with cement mortar
  • For cement plaster curing should be started 24 hours after finishing – 7 days
  • For red oxide flooring,
    • First day – cure the floor by sprinkling water every two to three hours for a whole day, to avoid a dry floor.
    • The second day – a thin sheet of water should be stocked up to check if white patches appear on the floor. If they do, remove the water, rub them off with a cloth and again refill water, until no white patches are visible.
    • Once the floor is laid, no one should walk on it for a minimum of four days, except for watering and waxing.
  • • For tiled flooring, tiling work must be cured for at least 7 to 10 days, and fill the joints with grout and clean them properly after completion of curing period.