聚丙烯纤维对橡胶混凝土韧性特征的影响研究

Study on Influence of Polypropylene Fiber on Toughness of Rubberized Concrete

在橡胶混凝土中,掺入聚丙稀纤维,以提高其韧性。结合室内试验对聚丙烯纤维增强橡胶混凝土的抗弯拉、抗压和抗冲击性能进行了测试分析,并对增韧机理进行了微观分析。结果表明:随着聚丙烯纤维的加入,弯拉强度、弯曲韧性和抗压强度均呈现先增大后减小的趋势,当纤维掺量为0.8%时达到峰值,破坏模式发生变化;抗冲击性能随着纤维掺量的增大而快速提高;在水泥基体中掺入橡胶粉后相当于引入大量低弹性模量的惰性物质,导致水泥基体初裂强度和断裂韧度的降低,从而有利于纤维桥联作用的发挥和多缝开裂的实现;综合考虑聚丙烯纤维的合理掺量不宜超过0.8%。

Rubberized concrete may have higher roughness with incorporation of polypropylene fiber. With indoor tests, the bending tension, compression and shock resistances of the polypropylene fiber reinforced rubberized concrete were tested and analyzed, with microscopic analysis on the toughening mechanism carried out. The results show that, as incorporation of polypropylene fiber, all of the bending tension strength, flexural roughness and compression resistance present a trend of increase first and then decrease, and reach the peak when the proportion of the fiber is 0. 8 % ; at this time, the failure mode changes. The shock resistance improves fast with increase of the fiber proportion; incorporation of rubber powder into cement matrix is equivalent to introduction of large amount of inert substance with low elastic modulus, leading to decrease of crack initiation strength and fracture roughness of the cement matrix, which is beneficial to fiber bridging and multiple cracking. Given the factors aforesaid, it is suggested that the reasonable proportion of polypropylene fiber should be less than 0. 8 %.