Experimental Study On Chloride Ion Erosion Of Polypropylene-fiber Concrete Subjected To High Temperature

With the development of the times, constitution of the architecture is becomingmore and more complex, and the structure is increasingly novel, leading toconstruction fire with the three major characteristics such asmultiple, catastrophic, complexity. Therefore in-depth study on evaluation ofstructural fire resistance and fire resistance design technology has become a necessarytopic. In concrete engineering, our country has conducted lots of researches on themechanical properties of concrete and steel under high temperature, residual strengthand failure modes of the various structures after high temperature, but for thelong-term effect caused by fire to the structure namely the durability are not attractedenough attention.The article took polypropylene fiber concrete as the research object, applyingmethods of quantitative analysis, studied high temperature performance and chlorideion diffusion properties of polypropylene fiber concrete subjected to high temperature,and provided a theoretical basis for the further promotion and application ofpolypropylene fiber reinforced concrete. Main researches are as follows:(1) High temperature test of concrete was conducted to study the performance ofconcrete under different fiber contents and different temperature conditions, at thesame time observed apparent damage characteristics after exposure to hightemperature, and analyzed mainly on the residual strength, water absorption, relativedynamic elastic modulus, mass loss, etc. for these four technical indicators. Theresults showed that, polypropylene fiber can improve temperature burst performanceof concrete, and the performance is better than plain concrete.(2) Rapid chloride migration test of concrete (RCM method) was conducted,studied chloride ion diffusion properties of concrete under different fiber contents anddifferent temperature conditions, measured its penetration depth, and calculated thepermeability coefficient respectively from two aspects of fiber content andtemperature as the main performance index for quantitative analysis. Results showed,high temperature affected greatly not only on the mechanical properties of concrete, but also the chloride ion diffusion properties of the concrete, and when thepolypropylene fiber content was higher than a certain scope, it would be harmful tothe chloride ion diffusion performance of concrete.