Experimental study on the compression properties of gangue by considering the effect of solutions with different pH

A type of complex aqueous solution was formed after water undergoing physical and chemical reactions with coal and rocks in mines, which penetrated into goaf through open fractures, thus influencing the bearing capacity and compression properties of broken gangue in goaf. To reveal the effect of solutions with different pH on the compression properties of gangue, the compression properties of gangue samples soaked in solutions were tested based on one-factor-at-a- time experimentation using a self-made compactor and a WAW-1000D electro-hydraulic servo-controlled universal testing machine. To do so, the effects of four factors (i.e. particle size distribution of gangue, pH of solution, solid-to-liquid ratio, and soaking time) on the compression properties of gangue samples were investigated. The changes in axial strain and porosity of gangue samples during compression as well as that of the particle size distribution before and after compression were analysed. The test results showed that the bearing capacity and compression properties of gangue soaked in solutions were degraded to some extent. The research provides an experimental basis for prediction and control of compression-induced deformation of gangue used for backfill under the effect of solutions with different pH.