Study on the properties and reinforcement mechanism of the novel high-strength and easy-to-inject ultrafine cement-based grouting material

• A new type of high-strength and easily injectable ultrafine cement-based grouting material has been developed to reinforce the surrounding rock of wind-oxidized zones. • The grouting stone body obtained from multiple rock-breaking grouting experiments was used to study the diffusion process of the grout under reduced conditions. • Prior to the XTDIC test, the samples were marked, and surface characteristics were recorded. Combined with strain contour maps, the macro damage feature was obtained. • The distribution of cement hydration products and the reinforcement of surface pores in the samples were investigated by SEM tests. The results show that this new grouting material has a good reinforcement effect on wind-oxidized fractured rocks. The coal and rock mass in wind-oxidized zones experiences significant weathering and oxidation, leading to changes in its mechanical properties. The rock becomes loose, fragmented, and more susceptible to modification, reducing its bearing capacity and roadway stability. To address the loose and fragmented surrounding rock in wind-oxidized roadways and the challenges in supporting them, ultrafine slag powder and sodium silicate modified ultrafine cement-based grouting materials are introduced. A new high-strength and easy-to-inject ultrafine cement-based grouting material has been developed. Through indoor experiments, the rheological properties and setting-hardening characteristics of the new grouting material were analyzed. Grouting tests on fractured rock masses were conducted using a self-developed grouting and reinforcement test device for broken rock masses, allowing for analyzing grout diffusion characteristics and the mechanical properties of reinforced rock masses. The results show that incorporating ultrafine slag powder and sodium silicate enhances the strength of the new ultrafine cement composite material, shortens the setting time, and ensures the flowability and setting rate of the new grouting material. This new ultrafine cement composite grout demonstrates good diffusion effects and high injectability in fractured rock, providing strong reinforcement. Moreover, the new grouting material exhibits a strong reinforcing ability at the grout-rock interface, where hydration products provide a strong "adhesive force", improving the soft, brittle, and easily destructible nature of wind-oxidized rocks. This new grouting material effectively addresses the issues of fragmented, soft, and low-bearing-capacity rocks, offering a reasonable solution for reinforcing the surrounding rock in wind-oxidized zones.