What is Curing?
Curing of concrete is the process that helps maintain the moisture in the concrete.
Why Curing The Concrete Is So Important?
We all know that concrete is a mixture of Cement, Sand, Stone and Water. One the all the ingredients are mixed the hydration process starts. Hydration is the process is a chemical process when the Cement-Water paste transforms into calcium silicate hydrate. This Calcium Silicate Hydrate is what makes concrete gets its strength.
Once the concrete is placed in the formwork, initial setting of cement starts. It generates a lot of heat and the concrete starts to lose the water in it through evaporation. Even after the initial setting time the concrete keep losing the water due to the external temperature conditions.
When the concrete is poured and starts setting it is a porous material. When hydration process continues the concrete keep getting denser and denser and as a result become rough, strong and durable. As long as the concrete contains its moisture it keeps adding strength to itself. If we do not cure the concrete it loses its moisture and the hydration process slows down and the concrete stops getting its strength. This is why the concrete should be cured as long as possible.
Methods Of Curing
There are multiple methods adopted for curing the concrete. The ultimate purpose is to maintain the moisture of concrete. Here are some of the methods :
Moist curing is done by keeping exposed surface of concrete in a wet condition by ponding or covering with a layer of sacking, canvas or similar material kept in wet condition.
Curing compounds can be applied to all exposed surfaces of the concrete instead of moist curing as soon as possible once the concrete is set. These compounds are chemicals that form a membrane on the concrete surface once dried.
Covering The Concrete
Impermeable membranes such as polythene sheets covering closely the surface of concrete provide effective barrier against evaporation.
When To Start Curing the Concrete?
When to start curing the concrete is an important question. Curing should start as soon as the initial setting of concrete is achieved. If we start curing too early the water we pour onto the concrete will take all the cement away from the concrete. So it is very important to let the concrete set and become firm. Curing can be started just after this.
How Long to Cure?
As long as the concrete keep getting moisture it keeps increasing the strength, So its better to cure as long as possible. But, because it is not practically possible, the curing of concrete should be continued till the final setting time of cement. IS : 456-2000 says concrete should be kept in the wet or damp condition for at least 10 day from the date of placing in case of ordinary Portland cement and 14 days in case the concrete with mineral admixture.
So, What we learned today?
- Curing the concrete is important because it provides proper atmospheric condition for concrete to keep gaining strength and make it durable.
- Curing should start as soon as the concrete is set.
- 10 days is the minimum period for which concrete should be in wet condition..
Hope the post was useful.
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