The effects of some organic acids and salts on the setting of gypsum plaster. I. Acetates

Abstract

AbstractThe properties of one batch of autoclave calcium sulphate hemihydrate have been determined. A study has been made of the effects of various concentrations of acetic acid, and potassium and calcium acetates on (i) the rate of evolution of heat, (ii) the setting expansion, (iii) the setting time, (iv) the compressive strength, (v) pH and (vi) the crystal morphology of this plaster. A theory of Ridge et al. has been tested and is discussed.It has been shown that the three additives have some similarities in their effects on the kinetics of setting and it is concluded that the acetate ion plays a major role in the observed retardation of setting.