ABSTRACT

Concrete accelerators increase the rate of hardening of cement and concrete mixes. The major material used to obtain this effect, calcium chloride, has been used since 1885 [1] and finds application mainly in cold weather, when it allows the early strength gain to approach that of concrete cured under normal curing temperatures and, probably more importantly, reduces the setting time so that finishing operations can proceed without undue delay. In this way, shutter and mold stripping, lifting and handling of precast items and finishing of flatwork can proceed normally. In addition, the concrete is less liable to damage by early age freezing. In this latter respect it should be pointed out that calcium chloride is not an antifreeze in the sense of significantly lowering the freezing point of water in the mix, so that although the time required for protection is reduced, the standard procedures for protection should be followed for cold-weather concreting.