Concrete is the world’s second most consumed material. It is an important component during construction, and its versatility, availability, and durability make it necessary for modern construction. Curing concrete is necessary to retain its natural strength and durability.
Curing is the process of keeping the concrete damp or moist so that it remains hydrated and the structure’s strength is maximised. This procedure should be carried out as soon as the concrete is set or after the formwork is removed. It is important to keep this process going for a decent amount of time so that the concrete can develop hardness and durability. This entire operation should be carried out while maintaining a constant temperature throughout the full depth of the concrete. This is done to prevent heat shrinkage and cracking. The major goal is to monitor moisture loss by keeping the concrete saturated or almost saturated with water.
Concrete curing: Aim
- To assist the concrete in achieving maximum strength through optimal hydration.
- To minimise the formation of fractures and hence increase its durability
- To improve its abrasion resistance and therefore, its performance
- Improved microstructure requires better hydration gels and solid bulk.
Concrete curing: What procedures are utilised to cure concrete?
Concrete may be cured in three different methods. The technique used, however, is determined by the location and its restrictions, the type of structure to be cured, and any other material limits. The following are the methods of curing:
Method of curing using water
Water curing is the process of continuously flowing water over the surface of the concrete. This is done to avoid water loss from the concrete surface. Spraying or sprinkling water or even curing ingredients over the concrete surface is an efficient curing procedure. Water healing is accomplished by:
- A. Ponding
- B. Sprinkling
- C. Fogging or mist curing
- D. Wet coverings
Membrane curing method
This procedure entails coating the surface of the concrete with an impermeable membrane to prevent moisture loss. Acrylic, wax, and water-based solutions are among the chemicals employed. Typically, the chemicals are sprayed over the surface of freshly placed concrete to form a barrier or impermeable membrane. Membrane curing is accomplished by:
- A. Plastic sheeting
- B. Formwork
Steam curing method
Curing in water vapour or at atmospheric pressures. It keeps the surface wet while also raising the temperature of the concrete. The procedure also includes the development of humidity surrounding the concrete in order to accelerate the hardening and strength of the concrete. This type of curing is used mostly for precast concrete factories or when formwork must be done fast.
Shading method
To generate shade, canvas stretched on frames can be utilised. This technology is typically applied on large concrete surfaces such as road slabs. This is important in dry weather to protect the concrete from heat, direct sunshine, rain, and wind. In cold weather, the primary objective of shade is to keep the warmth of the heat of hydration of cement, preventing the concrete from freezing.
Ponding method
This is the most successful method of treatment. It may be applied to horizontal surfaces such as floors, roof slabs, roads and airport pavements. Ponding can also be done on beams’ horizontal top surfaces. The exposed surface of the concrete is initially covered with damp gunny sacks or canvas in this process. After 24 hours, the coverings are removed, and little clay or sand ponds are built across and along the pavements to split it into pieces. Depending on the weather, the water is poured between the ponds and replenished two to three times every day. Although this method is quite effective, it needs a large amount of water. Ponds may be easily broken, enabling water to drain. Cleaning the clay once it has dried is also difficult.
Steam curing
In moist or wet circumstances, steam curing is performed by increasing the temperature of the concrete. This method allows the concrete to attain its optimum strength in a short amount of time. It is most commonly used for precast components.
Curing period for concrete
The final strength is determined by the curing process. Concrete curing should commence as soon as the concrete reaches its initial setting time or the formwork/shuttering is removed. In order for the concrete to attain the necessary strength and durability, the procedure should be repeated for a suitable amount of time in accordance with the established criteria.
- Brickwork should be allowed to cure for a minimum of seven days.
- Allow at least 15 days for reinforced cement concrete to cure.
- There is no need for curing during the wet season.
FAQs
What is the goal of curing?
Curing is essential for developing concrete strength and durability. Curing occurs immediately following the placement and finishing of concrete and entails maintaining ideal moisture and temperature conditions, both at deep and on the surface, for extended periods of time.
What is curing time in the building industry?
Concrete usually cures in 24-48 hours, at which point it is safe to walk on. After one week, concrete is usually sufficiently cured to support continuous construction, including heavy gear. After 28 days, concrete is regarded to have reached its full strength.