高温后纤维混凝土微结构与力学性能研究

Study on microstructure and mechanical properties of fiber reinforced concrete at high temperature

通过对聚乙烯醇(PVA)纤维和聚丙烯(PP)纤维两种合成纤维混凝土进行200、500℃高温处理,利用扫描电镜(SEM)及其实时拉伸测试系统,探究纤维混凝土在热力作用下,混凝土内部微结构与力学性能的演变关系。结果表明:PVA纤维、PP纤维的加入,有利于混凝土高温后抗拉性能的提高;弹性模量高的PVA纤维相比于弹性模量低的PP纤维对混凝土抗拉伸性能提升更好;温度从20℃变化至500℃,纤维混凝土试件的抗拉强度先上升后下降。

The polyvinyl alcohol(PVA)fiber and polypropylene(PP)fiber synthetic fiber concrete were treated at 200℃and 500℃respectively.Scanning electron microscope(SEM)and its real-time tensile testing system were used to explore the evolution relationship between the internal microstructure and mechanical properties of fiber concrete under thermal action.The results show that the addition of PVA fiber and PP fiber is beneficial to the improvement of tensile properties of concrete after high temperature.Compared with PP fiber with low elastic modulus,PVA fiber with high elastic modulus can improve the tensile property of concrete better.When the temperature changes from 20℃to 500℃,the tensile strength of the fiber reinforced concrete specimen first increases and then decreases.