Adding excessive amounts of water in concrete mix will increase slump and makes the concrete more workable. However, on the other hand it will reduce the desired strength of concrete. The strength will than decreases with increase in water content.
The added water dilutes the paste and increases the water-to-cement ratio (w/c). Sometimes it results in segregation, bleeding, and lead to other service related problems like leakages, cracks etc.
Curing is the last and one of the most important activity of concrete construction. Curing is the process of maintaining moisture in concrete. It significantly improves the overall quality of concrete. Rather without proper curing; even all other things being correct, you may not get desired strength or may get poor strength or less life. Once concrete casting has done, hydration will start and it will release heat. This released heat is always proven as harmful in volume stability. Heat also makes concrete dry and cracks are formed due to drying shrinkage, plastic shrinkage & thermal effects. The heat generated can be reduced by means of water curing.
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Water curing replenishes the moisture in concrete and allows the cement to hydrate, which allows concrete to gain strength. For hydration to continue, the relative humidity inside the concrete should be maintained. Therefore, more quantity of water required is for continuously to replenish, to avoid dryness, and to maintain humidity.
Best Construction methods and quality control measures will be of no value if curing is not done properly. Inadequate, intermittent or improper curing means that the resulting concrete will not achieve its desired strength.
The amount of water in concrete controls many fresh and hardened properties of concrete. For these reasons, limiting and controlling the amount of water in concrete is important for durability of structure.