Abstract
Crystal gypsum, magnesia and magnesium chloride were obtained as byproducts from salt making plants, and they were studied to be used as valuable and special gypsum-magnesia cement. Magnesia cement (xMgO·MgCl2·yH2O) is unstable owing to its weak water proofness and weak hardened strength changeable by the mixing proportion of magnesia and magnesium chloride solution, the concentration of magnesium chloride solution, the calcining temperature of light magnesia, etc.
These defects of magnesia cement were excluded by adding some parts of (1) calcined gypsum (CaSO4·1/2H2O) to light magnesia to make speciai gypsummagnesia cement,(2) calcined dolomite (CaO+MgO) or dolomite plaster (Ca(OH)2+Mg(OH)2) to make special dolomite-magnesia cement, or (3) both of light magnesia and calcined dolomite to make special gypsum-dolomitemagnesia cement. These three kinds of special magnesia cements were studied by systematically comparing with common simple magnesia cement, and the results of the first special gypsum-magnesia cement and the seeond special dolomite-magnesia cement were especially reported in the present report.
