氢氧化钙掺量对硅酸镁基胶凝材料性能的影响

Effect of calcium hydroxide content on the properties ofmagnesium silicate-based cementitious materials

采用氢氧化钙(Ca(OH)_(2))对硅酸镁基胶凝材料中的原材料MgO进行了不同质量比例的替代,对其流动度、凝结时间和抗压强度进行了测试,并结合X射线衍射(XRD)、扫描电子显微镜(SEM-EDS)、热重分析(TG-DTG)和压汞测试(MIP)分析了影响机理。结果表明,Ca(OH)_(2)能够显著增大硅酸镁基胶凝材料的流动度与抗压强度,缩短其凝结时间。XRD、SEM-EDS、TG、MIP测试结果说明了抗压强度提升的原因:Ca(OH)2与硅灰反应生成了C-S-H凝胶,并且促进了MgO的水化,提高硅酸镁基胶凝材料的水化程度,使其孔隙率显著降低。

In this paper,Ca(OH)2 was used to replace the raw material MgO in magnesium silicate base cementing material with different mass ratios,and its fluidity,setting time and compressive strength were tested.The influence mechanism was analyzed by X-ray diffraction(XRD),scanning electron microscopy(SEM-EDS),thermogravimetric analysis(TG-DTG)and mercury injection test(MIP).The results show that Ca(OH)_(2)can significantly increase the fluidity and compressive strength of magnesium silicate based cementitious materials,and shorten the setting time.The results of XRD,SEM-EDS,TG and MIP showed the reason for the improvement of compressive strength.Ca(OH)_(2)reacted with silica fume to form C-S-H gel,and promoted the hydration of MgO,improved the hydration degree of magnesium silicate based cementative material,and significantly reduced its porosity.