ACCELERATORS.

Abstract

Accelerating admixtures are used in cold weather concreting operations. A significant increase in the rate of early strength development at normal or low temperatures enables reduction in the curing and protection periods necessary to achieve specified strengths in concrete. Many substances are known to act as accelerators for concrete. They include alkali hydroxides, silicates, fluorosilicates, organic compounds, calcium formate, calcium nitrate, calcium thiosulfate, aluminum chloride, potassiuim carbonate, sodium chloride, and calcium chloride. Of these, calcium chloride is the most widely used because of its ready availability, low cost, predictable performance characteristics and successful application over several decades. Many aspects of the action of calcium chloride are controversial, ambiguous or incompletely understood. Attempts have continued to find an effective alternative to calcium chloride because of some of the problems associated with the use of calcium chloride.