玄武岩-聚乙烯醇纤维水泥基材料的高温性能

High-temperature performance of a basalt / polyvinyl alcohol hybrid fiber cementitious composite

为改善工程水泥基复合材料在高温环境下的服役性能,本文制备了玄武岩-聚乙烯醇混杂纤维工程水泥基复合材料。利用圆柱体抗压和狗骨型抗拉试件探讨玄武岩纤维对高温后力学性能的影响,并使用扫描电子显微镜和纤维断裂空间方法进行机理分析。试验结果表明:玄武岩纤维在高温后依旧填充在基体内部并传递微裂缝间的应力,其最佳的替换掺量为0.9%,此时抗压强度、弹性模量和抗拉初裂强度在600℃后分别较基准组提高了80.08%,101.83%和114.38%。同时机理分析表明:玄武岩纤维在受拉时往往在脱粘阶段发生断裂,过早失去对桥连裂缝的贡献,使其无法改善聚乙烯醇纤维融化引起的受拉脆性。

To improve the serviceability of engineered cementitious composites under a high-temperature environ-ment,a basalt and polyvinyl alcohol fiber reinforced hybrid fiber engineered cementitious composite was developed.Cylinder and dumbbell specimens were used to investigate the effect of basalt fiber on compressive and tensile per-formance at elevated temperatures.Scanning electron microscopy and fiber rupture space were used to conduct the mechanism analysis.The test results revealed that basalt fiber can fill in the matrix and transfer stress among micro-cracks at elevated temperatures.Its optimal volume fraction was 0.9%,where the compressive strength,elastic modulus,and first-cracking strength were higher than those of the control group by 80.08%,101.83%,and 114.38%at 600℃.Meanwhile,the mechanism analysis results demonstrated that basalt fiber tends to rupture at the debonding stage,thus losing its contributions to crack bridging and being unable to improve the tensile brittle-ness caused by the melting of the polyvinyl alcohol fiber.