Curing of concrete and it's methods, Importance of curing

 Curing:-

It is a procedure that is adopted to promote the hardening of concrete under conditions of humidity and temperature which are conducive to the progressive and proper setting of the the constituent cement.

Importance of curing:-

Following are the the importance of curing of concrete.

• To maintain moisture content in the mix for complete hydration of concrete.
• To maintain uniform temperature of the concrete.
• To preserve the properties of concrete, such as impermeability, durability and strength.
• To reduce the shrinkage of the concrete.

Methods of curing:-

1. Sprinkling of water

• This is useful method for curing vertical or incline surfaces of concrete.
• The spring can be done in fine streams throw nozzles fixed to a pipe spaced at set intervals.
• Slogging is done in the same way accept that the slogging nozzles produce a mist like effect, whereas spraying nozzles shed out fine spray.

2. Wet straw or damp earth:-

• In this method the damp Earth aur sand in layers of 50 mm height are sprayed over the surface of concrete pavements. The material is kept moist by periodical sprinkling of water.

3. Ponding of water over the concrete surface after it has set:-

This is the most common method of curing the concrete slab for payments and consists of storing the water to a depth of 50 mm on the surface by constructing small puddle clay bunds all around.

4. Cover the concrete with wet burlap:-

The concrete is covered with burlap as soon as possible after placing, and the material is kept continuously moist for the curing period.

5. Formwork or leaving the shuttering:-

The thick watertight formwork also payments the loss of moisture in concrete and helps in curing the sides and the base of the concrete.

6. Cover with waterproof paper:-

Waterproof paper prevents loss of water in concrete and protects the surface from damage. A good quality paper can be often reused. The paper is usually made of two sheets struck together by rubber latex composition.

7. Membrane curing:-

• The process of applying a membrane forming compound on concrete surface is termed membrane curing.
• Often, the term membrane is used not only to refer to liquid membranes but also to a solid sitting used to cover the concrete surface.
• The curing membrane serves as a physical barrier to to prevent loss of moisture from the concrete to be cured.
• A curing liquid membrane should dry within three to four hours to form a continuous coherent adhesive film free from pin holes and have no deleterious effect on concrete.

8. Chemical curing:-

• Chemical curing is is accomplished by spraying the sodium silicate solution on concrete surface.
• About five hundred gram of sodium silicate mixed with water can over one metre square of surface and from a hard and insoluble calcium silicate film.
• It actually acts as a case hardener and curing agent.