Mechanical performance of cemented gangue backfill body under coupling action of load and sulfate environment

The cemented gangue backfill body (CGBB) in the backfill mining is not only subjected to the axial compressive stress of overlying strata but also corroded by mine water. To study the mechanical properties of CGBB under the coupling action of axial load and mine water with sulfate, stress corrosion tests were carried out considering the Na2SO4 2 SO 4 solution concentration, loading stress level and initial loading age. The changes in surface characteristics, ultrasonic pulse velocity (UPV) and compressive strength were examined, and the strength deterioration model under the influence of multiple factors was established. The microscopic mechanism was analyzed through the testing results of SEM and XRD. The results showed the compressive strength and UPV of eroded CGBB both increased first and then decreased with the increase of soaking age. The deterioration of CGBB increased with the increase of the Na2SO4 2 SO 4 solution concentration. The stress level significantly affected the deterioration process of eroded specimens. The sulfate resistance of CGBB gradually increased with the increase of stress levels. When the stress level is 60 %, the sulfate resistance increased with the decrease of the initial loading age. The research results can provide significant guiding value for the design of CGBB.