Originally, the science of admixture was the province of a specialist, but with advanced building technology and ever increasing new demands on builder, engineer and architect it is necessary that all involved in building have as much knowledge of admixtures and their effects as of cement, aggregate or the mixing water. The amount of calcium chloride to be used for a particular job depends on the requirements, although it is generally recommended that the dosage should not exceed 2 per cent by weight of cement. Calcium chloride is available as pellets or other granules, flakes, or in solution form. The regular flake form contains a minimum of 77 per cent calcium chloride and the pellet and other granular forms a minimum of 94 per cent. If any lumps develop during storage they should be discarded.
Calcium chloride is soluble in either cold or hot water.
In making a solution it is good practice to add the salt to the water, for if water is added to the salt a hard coating forms, making dissolution slow. Freshly made, the solution is warm and should be cooled before use. Very concentrated solutions of calcium chloride are not prepared because of the possibility that excess chloride will settle to the bottom. It then becomes practical, though not exact, to add 1 quart of standard solution per sack of cement when 1 per cent calcium chloride is specified or 2 quarts per sack for 2 per cent calcium chloride. The solution is considered to be a part of the mixing water for concrete.