Experimental investigation into the mechanical and microscopic properties of cemented aeolian sand-coal gangue-fly ash backfill

Abstract

Abstract This paper investigates that the influence of the independent variables of particle size of coal gangue (CG), concentration and coal gangue content on the UCS of cemented aeolian sand (AS)-coal gangue-fly ash (FA) backfill (CACFB) mixtures through the thermogravimetric, piezomercurial, microscopic experimental means by adding certain particle size of coal gangue particles in the cemented aeolian sand -fly ash backfill (CAFB) mixtures. Through the relevant experiments, the following conclusions are drawn: 1. with the increasing particle size of CG particles, the UCS of the CACFB is increasing in which the 7d UCS of R-C-1, R-C-2, R-C-3 and R-C-4 were 2.05 MPa, 2.11 MPa, 1.94 MPa and 2.09 MPa, respectively; 2. After 7 days of curing age, the UCS of CACFB is generally 1.5 MPa higher than that of CAFB.; 3. Because CG particles play a role in increasing slurry concentration, compactness and improving particle gradation in CACFB, the UCS of CACFB is much higher than the UCS of CAFB.; 4. The improvement UCS of CACFB will greatly improve the popularization and application of filling mining in northern Shaanxi mining area, and reduce the damage to environmental water resources and land resources in the mining area.