玻璃纤维增强氯氧镁水泥的耐久性及其性能退化机理

采用热水加速老化试验和SIC(Strand in cement)试验方法研究玻璃纤维增强氯氧镁水泥(Glass fiber reinforced magnesium oxychloride cement,GRMC)的耐久性.通过分析试件的抗弯强度和变形特性,研究了50 ℃和80 ℃热水条件下GRMC加速老化的力学性能退化规律.运用X射线衍射仪(XRD)分析微观物相组成,并结合扫描电镜(SEM)观察老化过程中玻璃纤维在氯氧镁水泥基体中的腐蚀情况,分析其性能退化机理.结果表明,导致GRMC性能退化的主要因素是基体性能退化及由此造成的基体-纤维界面区的结构松散;次要因素是纤维腐蚀.纤维腐蚀程度与水泥基体性能有直接关系,若水泥基体的物相组成发生变化,玻璃纤维会发生化学腐蚀,导致材料性能下降.试验结果也显示抗水改性是提高GRMC耐久性的有效方法.

Durability and Performance Degradation Mechanism of Glass Fiber Reinforced Magnesium Oxychloride Cement

Durability of glass fiber reinforced magnesium oxychloride cement (GRMC) was investigated by using the accelerated aging technique and the strand-in-cement (SIC) test method. Development of flexural strength and the deformation characteristics of GRMC samples immersed in hot water of 50 ℃ and 80 ℃ were studied. Micro-phase composition and corrosion degree of glass fibers in the oxychloride magnesium cement matrix were observed by X-ray diffractometer (XRD) and scanning electron microscopy (SEM), and the degradation mechanism was also analyzed. Results show that major factors that cause degradation of GRMC are the performance degradation of the matrix and the looseness of interface structure. While the corrosion of glass fiber, which is closely related to cement matrix performance, also plays a role. Changing in phase compositions of cement matrix cause corrosion of glass fibers, which in turn result in degradation of the material performance. Results of the experiments also show that incensement in the water- resisting of GRMC can obviously improve its performance and durability.