Tensile and Fracture Properties of Silicon Carbide Whisker-Modified Cement-Based Materials

Silicon carbide whiskers (SiCw) have many excellent properties such as high strength, high elastic modulus, and high temperature resistance. In this paper, by using water reducer as dispersant, a stable SiCw dispersion was obtained, and SiCw-modified cement-based composites were prepared. Tensile strength tests for 8-shaped specimens were carried out on the materials. The fracture properties of the materials were measured using a three-point bending test with pre-cracks based on the digital image correlation method. The microstructure of the SiCw-modified mortar was observed by SEM. The results showed that the SiCw improved the tensile strength of the cement-based materials, and the addition of SiCw effectively improved the fracture toughness of mortar. The SiCw caused crack deflection during crack propagation, accompanied by whisker pull-out and bridging phenomena. The SiCw bridging effect and pull-out mechanism effectively controlled the crack propagation and played a toughening role, thus enhancing the crack resistance of mortar.