Are there any types of cement accelerators that we should know about that could be used instead of calcium chloride?
By far the best known and most widely used accelerator is calcium chloride. Many other materials have been found to accelerate the strength gain of concrete but, in general, they are seldom used, and only limited information is available concerning their effect on the properties of concrete. Most of the information given on accelerators applies mainly to the use of calcium chloride. Other chemicals that accelerate the rate of hardening of concrete include some other soluble chlorides, soluble carbonates, silicates, fluosilicates, alkali hydroxides, and some organic compounds such as triethanolamine, but many of these have a pronounced effect on setting as well, and may cause flash setting. Another method for accelerating the hardening of cement is steam curing, but such curing is ordinarily limited to precasting, where the whole member can be covered by a tarpaulin or plastic sheet to retain the steam. Steam should not be introduced until the concrete is at least two hours old. A different method of getting early strength is through the use of Type III cement. For even more rapid early strength development, regulated-set cement is useful (CONCRETE CONSTRUCTION, June 1972, page 273, and July 1972, page 335).