The weak water resistance of magnesium oxychloride cement(MOC) is the main reason for limiting its wide application. In this paper, the water erosion behavior and improvement measures in MOC were explored by water absorption test. The material dissolution time point was found from the mass change curve, which was controlled by the water resistance of 5 Mg(OH)2·MgCl2·8 H2O(P5) crystal. The point disappeared later after addition of the water reducer, which indicated that the water reducer improved the water resistance of the MOC. Capillary water absorption coefficient results showed that the water reducer improved the compactness of the MOC. The dissolution kinetics showed that the way to improve the water resistance of cement was to reduce aqueous solution temperature, increase the concentration of magnesium chloride in aqueous solution, and reduce the location of hydrolysis reaction. And the water reducer reduced the hydrolysis location by changing the morphology of the hydrated crystal and improving the cement compactness, and improves the water resistance of the cement. The performance test of MOC concrete indicated that water absorption test can characterize the water resistance of MOC and way.
magnesium oxychloride cement