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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。
The durability of glass fiber reinforced magnesium oxychloride cement (GRMC) was investigated by hot water accelerated aging test and SIC (Strand in cement) test method. By analyzing the flexural strength and deformation characteristics of the specimens, the degradation of the mechanical properties of GRMC accelerated aging under hot water at 50 ℃ and 80 ℃ was studied. The microscopic phase composition was analyzed by X-ray diffraction (XRD), and the corrosion of glass fiber in magnesium oxychloride cement matrix was observed by scanning electron microscope (SEM). The degradation mechanism was analyzed. The results show that the main factors leading to the degradation of GRMC performance are the degradation of matrix properties and the resulting loose structure of the matrix-fiber interface zone. The secondary factor is fiber corrosion. The degree of fiber corrosion is directly related to the properties of the cement matrix. If the phase composition of the cement matrix changes, the glass fibers will chemically attack, resulting in a decrease in material properties. Test results also show that water-resistant modification is an effective method to improve the durability of GRMC.