Effects of gangue particle-size gradation on damage and failure behavior of cemented backfill under uniaxial compression

• The compressive strength of gangue-cemented backfill first increases then decreases with increasing gradation coefficient, peaking at 4.28 MPa when the coefficient is 0.5. • Acoustic emission activity during loading exhibits three distinct phases: rising, active, and significantly active, reflecting progressive damage evolution. • Variations in internal pore and crack distribution due to different particle-size gradations lead to differences in acoustic emission characteristics and strength. • The study provides insights for optimizing gangue particle-size gradation to enhance the mechanical stability of cemented backfill in mining applications.