Effect of Curing Temperature on Mechanical Performance and Acoustic Emission Properties of Cemented Coal Gangue-Fly Ash Backfill

Abstract

Cemented coal gangue-fly ash backfill (CGFB), which is a mixture of coal gangue, fly ash, binder and water, is introduced and employed to fill underground mined-out areas of coal mines. Once placed, the CGFB mixtures should have favorable stability, which is closely relevant to the mechanical performance of the CGFBs. The mechanical behavior of CGFB is affected by the environment temperature. In this study, with the help of acoustic emission (AE) and infrared thermal imaging technique, the influence of curing temperature on the mechanical behavior of CGFB specimens is investigated. A uniaxial compressive strength (UCS) testing apparatus coupled with AE monitoring and infrared thermography is equipped to investigate the mechanical (UCS, elastic modulus, stress–strain relation), acoustic (AE cumulative counts and energy), and thermal (average infrared radiation temperature) properties of CGFB samples cured for different ages (1, 3 and 7 days) at various curing temperatures (20, 50, 75 and 90 °C). This study provides an effective coupled monitoring method for evaluating the performance of CGFB structures, and this can contribute to a better understanding of the thermo-mechanical-acoustic behavior of CGFBs, and thus a better design of stable CGFBs.