Research into the mechanical properties of wet-sprayed polypropylene fibre-reinforced concrete

As the depth of mines increases, the in situ stress increases gradually, resulting in increasingly demanding requirements for the support strength of coal-mine roadways and making it more difficult to provide this support. For this reason, more effective forms of support are needed. Concrete is a typical support form, but ordinary concrete has low support strength, cracks easily and is prone to brittle failure, whereas polypropylene fibre-reinforced concrete has a good inhibition effect on crack propagation and can remarkably improve the post-cracking performance and toughness of concrete. This paper studies the mechanical properties and application effects of wet-sprayed polypropylene fibre concrete in the mining context. A final mix proportion is obtained, a flexural toughness test on the round slabs of the concrete is conducted, and the corresponding initial cracking strength, peak strength, fracture energy and toughness are studied. This wet-sprayed polypropylene fibre concrete was applied and its application effect investigated. The results show that wet-sprayed polypropylene fibre concrete has advantages such as enhanced integrity and more uniform stress distribution. The initial cracking strength, peak load and energy absorbed of wet-sprayed polypropylene fibre concrete specimens are higher than those of dry-sprayed reinforcing mesh concrete specimens. An engineering practice application indicates that the resilience rate and dust concentration were significantly reduced during wet-sprayed polypropylene fibre concrete construction, and construction efficiency and economic benefits clearly increased. The research achievements are of great theoretical and practical significance in developing a further understanding of the fracture instability mechanism and mechanical properties of wet-sprayed polypropylene fibre concrete. This method may be applied widely in sinking and driving engineering to improve the support effect and ensure mine safety.