硫、氯氧镁混合胶凝体系凝结硬化性能及微观结构

Setting,Hardening Characteristics and Microstructure of Magnesium Oxysulfate and Magnesium Oxychloride Mixed Cementitous System

为了改善镁质胶凝材料的性能,结合硫氧镁水泥和氯氧镁水泥两个体系的特性,制备了硫、氯氧镁混合胶凝体系。通过测试凝结时间、抗压和抗折强度对混合体系的凝结硬化性能及耐水性进行了研究,利用XRD、SEM和EDS分析表征手段对混合体系水化产物的物相组成、元素分布及微观形貌进行了分析。结果表明:溶液中氯化镁质量分数增加,浆体的凝结时间延长,当氯化镁质量分数大于70%,凝结时间缩短。与硫氧镁水泥和氯氧镁水泥相比,混合体系的抗压强度降低、抗折强度稍有增加,浸泡28 d后表现出了良好的耐水性。XRD和SEM数据表明:晶体之间没有形成连结力强的连续结构,使混合体系的力学性能降低。浸水后水化产物微观形貌的改变是混合体系耐水性增加的主要原因。

In order to improve the performance of the magnesium oxychloride cement. Combine magnesium oxysulfate cement with magnesium oxychloride cement,mixed system was prepared. The setting hardening characteristics and water resistance were studied by testing setting time,compressive strength and flexural strength. Microstructure, ingredient distribution and phase composition were analyzed by means of XRD,SEM and EDS. The experimental results demonstrate that the setting time increase with the increase of magnesium chloride content when the magnesium chloride content is less than 70%. The compressive strength of mixed system decreases and flexural strength increases slightly,it shows better water resistance after immersion water 28 d. The data of XRD,SEM and EDS show that there is no strong continuous structure between crystal to make mechanical properties of mixed system reducing. The main reason of improving water resistance is the change of microstructure of hydration products after soaking.