Hydration mechanism of special‐purpose cements

Abstract

During baking of the raw mixture, a weak crystallization of hydraulically inert compounds is observed for these materials, providing a substrate for the growth of hydraulic compound crystals with limited solid solutions. As a result of grinding, cleavage of crystals will occur along the growth steps and intercrystalline boundaries, creating additional mechanical stress concentrators, which provides an increase in hydraulic activity. It appears that the full destruction of solid solutions does not occur, which results in strength enhancement of resulting hardened cement stone. The electron defects can also occur, having the form of deviations from distribution of electric charge corresponding to the regular structure of crystals. Upon hydration of the cements obtained from clinkers, highly basic hydrated newgrowths and active hydroxides are formed. At the same time, some leaching occurs on the surface of hydraulically inert compound resulting in a gelatinous hydroxide. With the lapse of time, gelatinous hydrate newgrowths transform to a crystalline state with decrease of basicity and lattice rearrangement into a more closely packed one. Amorphous hydroxides undergo crystalline aging and form a compactive crystallization frame around the grains of alkaline‐earth hydroaluminates.