Fiber Pull-out Test And Macroscopic Mechanical Properties Of Fiber Reinforced Cement-based Materials

Fiber reinforced concrete is a typical composite material,its mechanical property and fracture behavior largely depend on its meso-structure characteristics,in which,the bonding behavior between fiber and cement matrix is one of the main factors.In this paper,the interfacial bonding property between fiber and cement matrix was studied by a series of pull-out tests.Moreover,the mechanical model of single fiber pull-out was established and validated using the finite element method.The main work and results can be conclude as follows:First of all,through a series of fiber pull-out tests,the failure process of HPVA fibers,basalt fibers and glass fibers pulled out from cement matrix were studied,in which three kinds of embedment length of fiber and three different strengths of cement matrix were considered.Test results revealed that(1)the maximum pull-out load increased as the strength of the matrix or the embedment length of fiber increased;(2)HPVA fiber showed a significantly higher bonding strength in cement mortar than either glass fiber or basalt fiber;(3)the average shear strength can be more effective describe the interfacial shear bond property between fiber and cement matrix than the effective shear strength.Additionally,based on the optimum length of fibers in cement matrix,the effects of volume fraction of HPVA fibers,basalt fibers and glass fibers on the macro-mechanical properties of concrete were investigated,and then the optimum volume fraction for each fiber in concrete was determined.Furthermore,the macroscopic mechanical properties of fiber cement mortar were measured.The results showed that the bonding property between fiber and cement matrix had a significant effect on the macro mechanical properties of fiber reinforced cement mortar.As expected,the reinforcement effect of HPVA fiber on cement mortar is highest,followed by basalt fiber,and then glass fiber.Finally,the pull-out process of fiber from matrix and the failure process of fiber reinforced mortar were simulated and analyzed by the finite element method.The numerical results are in good agreement with the experimental results,which further explains the mechanism of the fiber in pull-out process and the reinforcing effect of fiber in cement mortar matrix.It means the results obtained from the fiber pull-out experiment can be used as parameters for the numerical simulation of fiber reinforcedcement matrix.