低坍落度聚丙烯纤维混凝土的高温后性能研究

为探索聚丙烯纤维(polypropylene fiber,PPF)长度和掺量对低坍落度混凝土的影响,设计了171组基准混凝土和PPF混凝土标准立方体试块,尺寸为150 mm×150 mm×150 mm,并开展了常温下和高温后低坍落度混凝土的抗压强度试验和劈裂抗拉强度试验.基于试验结果给出PPF对低坍落度混凝土抗压强度和劈裂抗拉强度的影响规律,并结合电镜扫描结果分析低坍落度PPF混凝土的微观结构和破坏机理.结果表明:在适宜的长度和掺量范围下,PPF的掺入较明显改善高温前后的力学性能;同时在一定掺量下,发现PPF高温气化有助于混凝土的应力释放,提高了残余抗压强度.

Study on the Properties of Low Slump Polypropylene Fiber Concrete After High Temperature

In order to investigate the effects of PPF additions (length and content) to low slump concrete, the 171 groups of cube specimens (150mm*150mm*150mm) were designed, and their compressive strength and splitting tensile strength were tested under normal temperature and after different high temperatures. Based on large numbers of experiments, the mechanism of PPF to low slump concrete on compressive strength and splitting tensile strength was discussed. In the meantime, the SEM was used additionally to analyze the microstructure and failure mechanism of low slump PPF concrete. The results show that the mechanical properties of PPF before and after high temperature are obviously improved under the appropriate length and dosage range. And the high temperature gasification of PPF with a certain amount of admixture is helpful to the stress release of concrete and improve the residual compressive strength.