What is curing? & Why Curing is so Important for concrete life?
Why Curing is so important for concrete?
We know curing is very important for concrete, but many people don’t know why curing is so important and what curing impact to the concrete. Lets know about curing.
What is curing?
When water is added to cement chemical reactions take place (hydration of cement) which result in the setting and hardening of cement. Mixing water is usually sufficient for the initial hydration of cement. If however, there is insufficient water in the concrete during the setting period for the complete hydration of the cement, the concrete does not develop its full strength.
Why Curing is Important for Concrete?
The strength of concrete increase with age provided moisture is present though at a much lower rate after a certain period. It is generally believed that cement keeps on hardening for at least one year. When concrete is laid, it’s water content is rapidly lost if sufficient precautions are not taken, by evaporation occasioned by the action of sun and wind and heat generated during setting cement. The prevention of such loss of water from concrete during it’s early life is know as curing.
If water in the concrete is allowed to evaporate, the cement will not have sufficient water for hydration and will set properly. The cement sets very rapidly in the initial stages, if it is not kept damp, the shrinkage effect will be very marked and there will be loss in strength of the concrete. After about fortnight the curing can be stopped as chance afterwards are very slow and the shrinkage that occurs in not very harmful.
The strength of a concrete is only 50 percent if is not damp cured of the strength if it is damp cured for 14 days, whist the strength is 25 percent more if continued for about a month.
When to start curing of concrete?
Water is to be applied for few days over the concrete surface soon after its setting because the hydration reactions between cement and water continue for a more extended period due to which hardening of concrete takes place.
The main functions of curing in concrete,
- 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.
Comparative strength of Ordinary Portland cement (OPC) concrete at various ages: – Approx.
3 Days 40 %
7 Days 65 %
28 Days 100 %
3 Months 115 %
6 Months 120 %
1 Years 130 %