Flexural performance, interface bonding and crack bridging mechanisms in 3D-printed metal mesh-steel fibre reinforced tungsten tailings

The cemented tailings backfill was placed in the upper layer, providing an artificial roof for subsequent excavation of the lower mining drift. Therefore, insufficient flexural capacity and brittle cracking have become the primary constraints on the stability of the backfill roof. To improve the early-age flexural performance of artificial-roof backfill, this study proposes an innovative reinforcement strategy using a hybrid combination of 3D-printed aluminium alloy metal mesh and steel fibres (3DPMM-SFCTB). An orthogonal test was designed with three variables: metal mesh pore (4.00, 6.00, 8.00 mm), wire diameter (1.00, 1.50, 2.00 mm) and steel fibre volume fraction (1.50 vol%, 2.00 vol%, 2.50 vol%). Flexural performance, interface bonding and microstructural characteristics were assessed via three-point bending tests and SEM-EDS analysis. The results show that the combined reinforcement system substantially improves the flexural resistance and deformation capacity of cemented tungsten tailings backfill compared with the unreinforced control (2.62 MPa). Different hybrid combinations exert distinct effects on flexural strength and toughness. Within the investigated parameter range, mesh pore size is the most influential factor governing flexural strength, whereas wire diameter has the greatest influence on peak deflection. The results provide laboratory-scale evidence for selecting reinforcement parameters for artificial-roof backfill in underhand mining.