Toughening Mechanism of Directional Fabric Woven Net and/or Non-Directional Short-Cut Fiber-Reinforced Sprayed Cement Mortar Thin-Plates.

In this paper, a non-directional short-cut polyvinyl alcohol fiber (PVA), directional carbon-glass fabric woven net, and a combination of these fibers were used to reinforce sprayed cement mortar (named FRCM-SP, FRCM-CN, and FRCM-PN accordingly), and the direct tensile and four-point bending tests of these three types of thin plates were conducted. It was shown that the direct tensile strength of FRCM-PN reached 7.22 MPa under the same cement mortar matrix, which was 175.6% and 198.3% higher than that of FRCM-SP and FRCM-CN, respectively; the ultimate tensile strain of FRCM-PN was 3.34%, which was 65.3% and 1291.7% higher than that of FRCM-SP and FRCM-CN, respectively. Similarly, the ultimate flexural strength of FRCM-PN reached 33.67 MPa, which was 182.5% and 519.6% higher than that of FRCM-SP and FRCM-CN, respectively. In addition, the tensile, bending toughness index, and residual strength factor of FRCM-PN were much higher than those of FRCM-SP and FRCM-CN, indicating that the incorporation of non-directional short-cut PVA fibers improved the interfacial bonding properties between the cement mortar matrix and the fiber yarn and significantly enhanced the toughness and energy dissipation capacity of the sprayed cement mortar. Therefore, the use of a certain amount of non-directional short-cut PVA fibers can improve the interfacial bonding properties between the cement mortar and the fabric woven net while ensuring the spraying performance and significantly improving the reinforcing and toughening effect on the cement mortar to meet the demand for large-area rapid construction and structural seismic reinforcement.