A Study Of The Capability For Fire Resistance Of Polypropylene Fiber Concrete For Tunnel Lining

The number and length of tunnels increases year by year with the development ofeconomy and transportation. Once fire has been taken place, it not only damages productsand belongings but also imperil peoples’ lives that are there. So the fire resistanceperformance of tunnel structure should not be ignored. Fire prevention of the tunnel lining isan important part of the tunnel fire safety, lots of tunnels fire cases domestic and abroadshow that fire to the serious damage of lining structure. In recent years the study shows that,polypropylene fibers have been mixed in concrete structure for its fire resistance. With theextensive applying of fiber concrete, the performance of concrete with polypropylenefiber(PPF) subjected to high temperature is very important.In this paper in a view of the tunnel lining concrete mixed with polypropylenefiber(PPF), the workability and the capability for fire resistance of concrete studied asfollowed.1. The first part of this paper studied the law for fiber in different length and differentcontent to the concrete slump, and summarized the effect of polypropylene fiber(PPF)onconcrete workability, and it studied the effect on compressive strength of concrete forpolypropylene fiber in different length and different content under different temperaturefield compared with plain concrete and summarized the changing rule of compressivestrength for polypropylene fiber concrete and plain concrete in different temperature field.The experimental results show that the compressive strength of polypropylene fiber concrete(PFC) and plain concrete decreases with increasing temperature, and fiber content in acertain range has a small effect on the compressive strength of the concrete.2. The second part studied the apparent change,the fracture development and thespalling for large panel specimens of the plain concrete and fiber concrete under hightemperature(polypropylene fibers in different length and in different content). Theexperimental results show that the polypropylene fibers (PPF) has a great influence on theanti-spalling behavior of concrete under fire loading to ensure the integrity of the structure，and it elaborates the application prospects and the mechanism of action of polypropylenefibers in the concrete.3. The third part on the basis of summing up the evaluation method of concrete afterfire, and the advantages disadvantages of various methods and the application scope. westudied the changing rules of dynamic elastic modulus under different temperature fields,and the chemical titration that detecting the fire damaged concrete.It provides a reference gist for the analysis and evaluation of the bearing capacity and destructiveness of firedamaged concrete.