RESEARCH ON THE WATER-RESISTANCE OF MAGNESIUM OXYCHLORIDE CEMENT——I:THE STABILITY OF THE REACTION PRODUCTS OF MAGNESIUM OXYCHLORIDE CEMENT IN WATER

摘要

In this paper.the change of the crystalline phasesin hardened magnesium oxychloride cement（MOC）paste inwater was analyzed by XRD.It was developed that the reactionproducts 5 phase or 3 phase of MOC are instable in water andcan be changed into Mg（OH）2 by the action of water,whichcauses the content of 5 phase or 3 phase to be less and less,thecontent of Mg（OH）2 to be more and more and the strength to bethe lower the lower,after hardended MOC paste was immersedin water.The change of 5 phase and 3 phase into Mg（OH）2 isnot a dissolve process,but a hydrolysis process.The hydrolysisproducts of 5 phase and 3 phase are Mg（OH）2 precipitationand soluble Cl-,Mg+ ions and H2O.The hydrolysis is sponta-neous thermodlynamically and its chemical kinatic equation is C=Coe-kt Thus,it is suggested that only by enhancing the stabilityof 5 phase or 3 phase in water and preventing 5 phase or 3phase from the hydrolyzing can the water resistance of MOC beimproved well.