YANG Rui 1, JIANG Guojian 1, SHEN Qingyi 2, CAO Weiping 1, WANG Youfeng 1, TU Tianzhe 1, ZHAO Qiancheng 1, SONG Hui 1, LIU Siyu 1
(1. College of Materials Science and Engineering, Shanghai Institute of Technology, Shanghai 201418, China; 2. Department of Prosthodontics, Shanghai Stomatological Disease Center, Shanghai 200031, China)
Abstract: The modified sulfur-oxygen magnesium cementitious materials were prepared by mixing industrial-grade MgO powder,MgSO4·7H2O solution and additive. The best preparing parameters of the modified sulfur-oxygen magnesium cementitious materials, the effects of MgO/MgSO4·7H2O molar ratio, the concentration level of MgSO4·7H2O and the addition of water glass on the mechanical properties of sulfur-oxygen magnesium cement were investigated. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to characterize the microstructure and phase compositions. The results show that the increase of MgO powder dosage will help improve the compressive strength of the sulfur-oxygen magnesium cementitious material. Reducing the concentration of the magnesium sulfate solution results in a negative growth trend of the compressive strength. When MgO/ MgSO4·7H2O /H2O molar ratio reaches 11:1:8, the complex admixture molar ratio reaches 9:1, the sulfur-oxygen magnesium cementitious material is found to have the best 28 d compressive strength of 118.5 MPa and the softening coefficiency above 0.95. The compressive strength and water resistance can be improved by the modification of sulfur-oxygen magnesium cementitious material.
Key words: magnesium oxy-sulfate materials; modified; performance