Hydration behavior of calcium phosphates is analogous to hydration behavior of calcium silicates

Similarities between the hydration of calcium silicates and calcium phosphates are discussed. Calcium silicate hydration forms C-S-K, while calcium phosphate hydration forms hydroxyapatite (HAp). Both are compounds of variable composition, both incorporate water, and both exhibit high surface areas. Although both are weakly crystalline, HAp is so because of small crystallite size. Calcium phosphates and calcium silicates both undergo pozzolanic reactions and Hadley grains form in both systems. The origin of Hadley-like grains and the mechanisms limiting the rate of hydration in the calcium phosphate system are described. (C) 1999 Elsevier Science Ltd. All rights reserved.