掺聚丙烯混凝土高温力学性能及微观孔隙结构试验

Experiments on High Temperature Mechanical Properties and Micropore Structure of Polypropylene Concrete

摘要: 聚丙烯纤维由于其良好的稳定性和机械性能掺入混凝土可有效防止混凝土高温爆裂，同时可以在一定温度范围内提高混凝土力学性能，本文对不同温度下普通混凝土掺聚丙烯前后多项力学性能(立方体抗压、立方体劈裂抗拉、轴心抗压、弹性模量)进行对比，得到掺入聚丙烯纤维在一定温度范围(<400℃)对混凝土力学性能有提升的结论。但随着温度的升高(>400℃)，掺纤维对力学性能几乎无影响；并针对400℃~500℃不掺纤维混凝土进行压汞试验，得到这一温度区间内混凝土孔径分布变化规律，在400℃~500℃温度区间孔隙率增加和50 nm以上孔快速增多，且孔隙率相比常温时增加很多。

Abstract: Because of its good stability and mechanical properties, the polypropylyne can effectively pre-vent concrete from bursting at high temperatures and can improve the mechanical properties of the concrete in a certain temperature range. In this paper, a number of mechanical properties (cubic comparison of compressive strength, cubic split tensile strength, axial compressive strength, and modulus of elasticity) were obtained, and the conclusion that the mechanical properties of concrete were improved by mixing polypropylene fibers in a certain temperature range (<400˚C) was obtained. However, with the increase of temperature (>400˚C), the fiber has almost no effect on the mechanical properties. The mercury pressure test was performed on the concrete without fiber in the temperature range of 400˚C~500˚C. The porosity of polypropylene fiber reinforced concrete increased in the temperature range of 400˚C~500˚C and the number of pores at 50 nm increased rapidly, and the porosity increased a lot compared with normal tem-perature.