Research On Damage Characteristic And Carbonation Performance Of Polypropylene Fiber Concrete Subjected To High Temperature

With the development of high-rise buildings, long-span bridges and special structures, high performance concrete is widely applied, the high performance concrete is prone to burst when suffered with high temperature or fire. Adding polypropylene fiber is one of the important means to improve the fire resistance performance of concrete. With the high performance concrete are becoming more widely applied and fires of buildings are becoming more frequently to happen, it is very important to research polypropylene fiber concrete properties at high temperature and durability after high temperature.This text’s object is Polypropylene fiber. It is based on experimental study, using the method of combining macroscopic analysis with microcosmic analysis to deeply research on microstructure and carbonation resistance of concrete after high temperature. It is aiming at exploring damage characteristics of polypropylene fiber concrete under high temperature, and mastering the rules of carbonization of polypropylene fiber concrete after high temperature. The specific contents are as follows:(1) Research on damage characteristics of polypropylene fiber concrete under high temperature.Use box-type resistance furnace to heat the concrete. Its temperatures are follows: normal,150℃,400℃,600℃and800℃. Through the observation of the changing of its surface color and crack case of concrete after high temperature, to carry on the preliminary analysis of the damage characteristics of polypropylene fiber concrete under high temperature;Break the concrete check bar to observe the internal damage of concrete at mesoscopic level; through scanning electron microscope test to study on the microcosmic morphology of polypropylene fiber concrete after high temperature and the effect of high temperature on polypropylene fiber concrete at micro-level.(2) Research on carbonization properties of polypropylene fiber concrete after high temperature.The test of the fast carbonation test of polypropylene fiber concrete after high temperature is to analyze the carbonation depth with time of polypropylene fiber concrete, and the effects of temperature and fiber content on the carbonization properties of polypropylene fiber concrete.The results show that:adding proper amount of polypropylene fiber can improve the performance of concrete under high temperature and the carbonization after high temperature. Adding high fiber content cannot improve the compressive strength of concrete. It will cause adverse effects on the carbonation resistance of concrete after high temperature at the same time.