Abstract:
The interfacial bonding mechanical properties of fiber-embedded cement-based materials play an important role in the mechanical properties of fiber-reinforced concrete materials. The pull-out test of single fiber can better simulate the stress conditions between the fiber and the cement matrix material interface. Therefore, a pull-out test of a single coarse polypropylene fiber from cement mortar matrix was carried out which considered three fiber diameters (0.2 mm, 0.6 mm, 0.8 mm), three fiber embedding lengths (10 mm, 20 mm, 30 mm), three fiber surface properties (indentation type, wave type, smooth type) and three kinds of cement mortar matrix water-binder ratio (0.66, 0.51, 0.41) influencing factors. The morphological characteristics of the fibers after being pulled out were observed by SEM, a numerical model of the fiber pull-out process was established by ABAQUS finite element to study the shear stress between a single fiber and the cement-based interface. At the same time, the experimental results and the simulation results were numerically fitted, and the influence rules of various factors on the interface bonding mechanical properties were obtained: (1) The optimum water-binder ratio of cement mortar is 0.41-0.49; (2) The embedded length of the synthetic crude polypropylene fiber is 8-10 mm, and the optimal fiber diameter is in the range of 0.26-0.39 mm; (3) When the fiber surface properties are indentation type, the utilization rate of fibers in cement-based materials is large, and the interface bonding performance with cement mortar is good.