Behavior of reinforced cemented tungsten tailings composites considering End-Hook, Molten-Drawn and Shear-Wave steel fibers

Abstract

Backfill incorporating fiber is increasingly utilized in mine fill applications, offering enhanced performance as a composite material influenced by fiber type and dosage. This study examines the impact of several sorts/dosages of steel fibers on strength characteristics of steel fiber-based cementitious tungsten tailings backfill (SFCTB). The steel fibers tested include End-Hook (EH), Molten-Drawn (MD), and Shear-Wave (SW) types, with dosages of 0.5 %, 1.0 %, 1.5 %, and 2.0 %. A control group was established, and 52 specimens were prepared for analysis. Uniaxial compressive strength (UCS) tests and SEM observations were conducted to evaluate strength and microstructural features. Results indicate that adding steel fibers at equivalent dosages enhances UCS and alters stress-strain curves' morphology. Post-fracture slopes of stress-strain curves moderated across different fiber types with identical dosages. The average peak strength of EH-2.0 %, MD-1.5 %, and SW-2.0 % shows the most significant changes, increasing by 50 %, 44 %, and 50 % respectively, with their compressive strengths reaching 1.88 MPa, 1.77 MPa, and 1.87 MPa. A quadratic relationship was observed between fiber dosage and UCS, with high R² values for the fitted equations. The R-squared values of the steel fiber-reinforced CTB samples (EH, MD, and SW) are 0.8352, 0.9794, and 0.9439 respectively. Increased steel fiber rate also raises the capacity required for SFCTB failure, primarily characterized by tensile damage. Steel fibers inhibit crack propagation and elongation within SFCTBs, enhancing structural integrity. Hydration yields (i.e., C–S–H gel, Aft) improve particle adhesion, internal compactness, and fill strength. This study's findings highlight how optimizing steel fiber type and dosage can enhance tungsten tailings utilization and fiber-reinforced fill performance, providing valuable theoretical guidance for the efficient application of these composite materials.