Particle size distribution of aggregate effects on the dynamic compressive behavior of cement waste rock backfill

Abstract

Cement waste rock backfill (CWRB) is an essential component of green mining. Recent studies have demonstrated that the CWRB can slow surface settlement and provide economic advantages. However, there has been only limited research into the susceptibility of CWRB to dynamic impacts such as rock bursts, especially as mining depth increases. This study aims to investigate the dynamic peak stress, elastic modulus, and dissipated energy of CWRB specimens using a split Hopkinson pressure bar system. The results demonstrated that the responses of aggregate with different particle size distributions to the system’s impact strain rate (ISR) were inconsistent. Specifically, the highest dynamic peak stress of 23.71 MPa was achieved for the CWRB (Talbot index = 0.6) at a low ISR (30 s−1–35 s−1) and 62.33 MPa for the CWRB (Talbot index = 0.4) at a high ISR (40 s−1–50 s−1). A strain nephogram and fractal dimension analysis further suggested that the CWRB (Talbot index = 0.4, 0.6) could continue to provide partial compressive resistance after impact. Moreover, a compressive model was developed to determine the “change point” between the low and high ISR. The model indicated that different particle size distributions influenced the porosity, and at a high ISR, the pore structures further worsened the dynamic compressive behavior of CWRB. This study not only enhances our understanding of the compressive performance of CWRB under dynamic impact, but also contributes to the safety and efficiency of filling mining operations. In addition, it offers a theoretical explanation of the effects on the dynamic compressive behavior of CWRB.