Modified gypsum binder

Abstract

Gypsum-based binder modified by clay has properties close to the gypsum binder and can be used as plaster formulations or mortars. There are several reasons and chief among them is the lack of scientific based theory of formation and hardening properties of gypsum-based binder modified by clay without additives and that modified by additives. One of the classic ways of studying the mechanism of hydration of gypsum binders is the analysis of the heat liberation: hydration heat of the binder. With the thermos method of determining the heat liberation the ambient temperature is constant and the temperature of the sample which was at the beginning of the experiment changes as a result of the released heat of hydration of the gypsum; heat exchange between sample and the environment. Heat transfer is minimized through the use of thermos technology and effective insulation. The article presents the results of studying the dynamics of heat liberation during hydration of gypsum-based binder modified by clay without additives, with addition of superplasticizer and with the addition of setting retarder. Results in all cases are satisfactory. The highest degree of hydration evaluated by kinetics of heat liberation from a binder is with the addition of the superplasticizer. Application of setting retarder somewhat reduces the maximum degree of hydration and increases the hydration time. The degree of hydration of the binder with the addition of C3 additive and retarder is observed to be higher than that of gypsum-based binder modified by clay without additives. The studies confirm the possibility of using gypsum-based binder modified by clay in the composition of dry plaster mixtures for interior decoration works in premises.