Properties of water used for concreting as per IS 456:2000Water reacts chemically with cement, the reaction being called hydration of cement, and brings about the setting and hardening of cement. Water also lubricates the mix and gives it the workability required to place and compact it properly. Water used for mixing in concrete should be free from oil, acids and alkali's, salts, sugars, organic materials, or any other substances that may be deleterious to concrete. Generally, it should be of potable quality. The pH value of water shall not be less than 6.
Seawater is not recommended for reinforced and prestressed concrete because of harmful salts present in it, but can be used only under unavoidable circumstances for plain concrete. It is well known that the chlorides and sulphate contents of water have a major influence on the durability of concrete. The permissible limits for solids in water are given in Table 1 of IS:456-2000 (clause no.5.4). Water used for curing should not produce any stain or unsightly deposit on the concrete surface.