The retarding action of sugars on cement hydration

Sugars retard the hydration of Portland cement. The effectiveness of different sugars is compared from studies of solution analysis, calorimetry, calcium binding ability and alkaline stability. The best retarders, sucrose and raffinose, have a remarkable ability to solubilize cement constituents and in particular give rise to dramatic increases in the amount of silica in solution. However, 13C and 29Si N.M.R. do not reveal the existence of sucrose-silicate complexes. The retarding action of sugars is explained in terms of adsorption onto and poisoning of hydrate surfaces.