Interfacial Properties Of Fiber Reinforced Concrete And Fiber Mechanism Of Action Studies

Concrete is most extensively used as architectural materials in latter day and is the largest artificial materials at present. It is prevalent in civil engineering because of its waterproof, plasticity, abundance, cheapness and easy operation. Thus it is believed that nothing can displace concrete as the most extensive architectural materials in a long time. But in the same time the flaws of the concrete prevent itself from application and good effect. The use of fiber concrete can improve the performance of concrete, so it is concerned more and more by research institutions and scholars since it is come into being.This paper studies the mechanism of changing in fiber concrete and summarizes the methods of improving performance of fiber concrete. The main tasks of the present paper are as follows:Firstly, the interfacial performance between fibers and concrete is studied. Then the change of shear stress in the interface is deduced in theoretical way after the fibers are disengaged and pulled out from concrete. In addition, the spring element is used to simulate the bond between fibers and concrete in FEM.Next, the improvement of fibers to concrete is analyzed from two aspects. On the course of hardening of concrete, the improvement of performance mainly lies in the decrease of plasticity cracks and interior cracks of concrete in quantity and in dimension and the enhancement of medium continuity. The stress field of concrete is altered because of the effect of the fibers, which will change the mechanics performance of concrete.Then, the methods of Fracture Mechanics are adopted to analyze toughness and strength of concrete, which considers the process of slip between fibers and concrete. On the working style of the fiber concrete structure, the fibers make a difference in preventing the fracture cracks from expanding, which improves the strength and toughness to a certain extent. Increasing the density of the transitional field between fibers and concrete structure and increasing the volume fraction, length, and externalroughness of fibers both can improve the strength and toughness of concrete structureeffectively. From the fracture mechanism of fiber concrete structure , some formulations as to the strength of fiber concrete are educed in the paper.Finally, some effective methods of improving working performance of fiber concrete structure are summed up and several suggestions are put forward for further research.