Abstract: In order to study the effect of cellulose fiber and basalt fiber content on the mechanical properties of sprayed concrete, work performance and mechanical performance tests were conducted on sprayed concrete with different fiber content. Based on the energy evolution curve, the energy changes at different stages of sprayed concrete were compared and analyzed, and the toughening and crack resistance mechanism of fibers on sprayed concrete was analyzed by combining macroscopic experiment and SEM. The results show that the addition of cellulose fiber and basalt fiber can lead to a decrease in the slump of sprayed concrete. The compressive strength and splitting tensile strength of sprayed concrete increase first and then decrease with the increase of the content of two fibers. Under the load action, the energy evolution curve of sprayed concrete mainly goes through four stages: initial damage stage, linear elastic stage, mutation damage stage and destruction stage. The incorporation of appropriate amount of cellulose fiber and basalt fiber enhances the crack resistance and energy consumption capacity of sprayed concrete. After adding cellulose fiber, the particle distribution of hydration products in the interface transition zone of sprayed concrete becomes more uniform, and the interface structure becomes smoother and denser. The friction between fibers and matrix provides the energy required for crack propagation, enhancing the ductility and crack resistance of sprayed concrete.

Key words: sprayed concrete, basalt fiber, cellulose fiber, mechanical property, energy evolution, microstructure