Orthogonal Analysis on Mechanical Properties of Basalt–Polypropylene Fiber Mortar

Orthogonal test method was applied to analyze the strength properties of basalt-polypropylene mortar. The effect of basalt fiber length, polypropylene fiber length, basalt fiber volume content and polypropylene fiber volume content on the 28 d cube compressive strength and flexural strength were investigated. Test results show that comparing with flexural strength, the influence of basalt fiber length and polypropylene fiber length on compressive strength of mortar was greater than on flexural strength. The length of polypropylene fibers contributes the highest to the flexural strength. The effect of basalt fiber on mortar strength is the largest with 6 mm length and 4% content. Polypropylene fiber length has the greatest influence on the compressive strength of fiber mortar, followed by basalt fiber volume content. Volume content of polypropylene fiber has the greatest influence on flexural strength of fiber mortar, followed by polypropylene fiber length. According to the scoring of the efficacy coefficient method, the best ratio combination for compressive and flexural strength was the basalt fiber length of 9 mm, polypropylene fiber length of 6 mm, basalt fiber volume content of 4% and polypropylene fiber volume content of 4%. Compared with the blank samples, the 28 d compressive strength and 28 d flexural strength of the cement mortar samples were increased by 27.4% and 49% respectively. According to the test results, the properties of the fiber were analyzed and evaluated and the mechanism of fiber action and fiber microstructure were analyzed.