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

To study the effects of gangue particle-size gradation on the damage characteristics of cemented backfill, investigation techniques such as uniaxial compression tests, acoustic emission, digital image correlation monitoring, and scanning electron microscopy were used from macroscopic and microscopic perspectives. The peak strength, acoustic emission characteristics, and failure modes of cemented backfills with different gangue size gradations were investigated. The test results indicated that with an increase in the gradation coefficient, the compressive strength of the gangue cemented backfill first increased and then decreased, when the gradation coefficient is 0.5, the maximum compressive strength of the backfill is 4.28 MPa. The acoustic emission counts during the loading of gangue cemented fills with different gradation coefficients passed through three phases: rising, active, and significantly active. Because of the different gangue particle-size gradations under the filler sample, the number of internal pores and cracks, and the distribution of the location of the unequal, causes differences in acoustic emission characteristics at the same stage and differences in the strength of the backfill.