Properties and hydration products of lightweight and expansive cements - Part II: Hydration products

The type and quantity of hydration products in cement stone (plain cement, lightweight cement with cenospheres, and cement mixed with expansive additi ve) hydrated at 20 and 75 degrees C were studied. The changes in the cement stone structure under the influence of lightweight and expansive additives and raised hardening temperature were studied with complex thermal analysi s, infrared spectroscopy, powder X-ray diffraction analysis, and scanning e lectron microscopy. In the case of raised hardening temperature, the cenosp heres and the expansive additive improve the crystallization of hydration p roducts. A chemical reaction between the cenospheres and portlandite formed from the cement hydration was observed, accompanied by a decrease of the p ortlandite quantity. The expansive additive stimulates the formation of hyd ration products, which were thermally stable and decompose at temperatures above 600 degrees C. (C) 1999 Elsevier Science Ltd. All rights reserved.