Study On The Bond-slipand Fractional Properties Of Oriented Steel Fiber Reinforced Cementitious Composites

Oriented steel fiber reinforced cement-based material(SFRC)is a composite material.The steel fiber have the reinforcing and toughening effect for the cement-based materials.Its effect depends on the interfacial bond slip between the fiber and matrix and the ability of steel fiber to prevent crack extension.The research on the interfacial bond slip and fracture properties of the oriented steel fiber cement matrix composites is still not perfect.This work supported by the key project of scientific and technical research in Hebei Province(ZD2015028)“investigation on fracture mechanism of Oriented Steel Fibre Reinforced cementitious composites ”and the National Natural Science Foundation of China(51578208)“investigation on Reinforcement mechanism and mechanical models of oriented steel fibre reinforced concrete”.Based on the theory of composite materials and fracture mechanics,the bond-slip and fracture properties of oriented steel fiber reinforced cementitious composites were studied from two aspects which were the influence factors of interfacial bonding properties between steel fiber and cement mortar and toughening effect of fiber on cement based materials the effect of fiber on cement matrix material.The main contents of my project are as follows.(1)Design the steel fiber cement mortar pullout test to study the production process specimens,fixtures steel fiber,device and load the appropriate test methods.A cement mortar specimens was prepared successfully through a simple preparation process.A series of pullout tests of single steel fiber were carried out by adopting four kinds of steel fiber types.The pullout process was analyzed through the curves of pullout load-slip and the improvement of interfacial bond strength of cement mortar was compared with the different steel fiber appearance characteristics.(2)The different angle embedded in cement mortar to carry out pullout tests,Comparing the test results and the improvement of interfacial bond strength of cement mortar was compared with the different angle embedded in cement mortar.(3)By controlling the steel fiber distribution and fiber orientation in the matrix to making prefabricated steel fiber cement mortar notched beam specimens.Use these specimens conducted a three-point bending test.The test results were processed to obtain specimen load-deflection and load-crack displacement curves,and calculate the fracture toughness specimens and fracture energy to study the influence of cement matrix fracture properties on the distribution and direction of the steel fibers.