Effect of 3D printed skeleton shapes on strength behavior, stress evolution and microstructural response of cement-based tailings backfills

Abstract

The inherent brittle behavior of cement-based tail backfill (CTB) poses some challenges that can significantly impact the safety and effectiveness of underground mining operations. Due to its propensity for abrupt and catastrophic failure without considerable deformation, CTB can endanger both the structural solidity of mined-out cavities and workers’ security. Hence, implementing appropriate strategies is critical to mitigate the risks associated with the brittle nature of CTB. An experiment investigation was commenced to consider the influence of diverse 3D printed polymer reinforcement geometries - specifically, hexagon, staggered quadrilateral, and rhomboid shapes - on strength behavior, stress evolution, and microstructural response of CTB via peak compression strength test plus scanning electron microscope observations. Lab findings specified a decrease in fill strength upon adding these polymer reinforcements. Specifically, the N-3D-PP-reinforced CTB exhibited a strength of 0.61 MPa. In comparison, the reinforced samples showed lower strengths of 0.39 MPa for the hexagon shape, 0.44 MPa for the staggered quadrilateral shape, and 0.45 MPa for the rhomboid shape. The toughness of CTB incorporating 3D-PP was higher than that of N-3D-PP ones. The optimal shape for an ideal toughness was the rhomboid shape, with a value of 58.06 KJ.m−3. N-3D-PP-reinforced CTB specimens exhibited a semi-brittle behavior, while 3D-PP-reinforced CTBs displayed a more ductile response with high total and dissipative energies. Cracks in N-3D-PP reinforced CTB were tensile, and mainly a combination of tensile and shear in 3D-PP reinforced CTB. Despite enhanced toughness, the presence of pores, the poor interfacial bonding between the CTB matrix and the 3D-PP, the low volume of polymer reinforcement, and the potential disruption of cement particle packing compromised the CTB's overall strength. This research highlights the potential of 3D-printed reinforcements in transforming the landscape of mining backfill technology. The findings pave the way for the widespread adoption of 3D-printed polymer-reinforced CTB in metalliferous mines, promoting safer, more productive, and, ultimately, more profitable underground mining operations.