Effect of magnetic induction intensity and steel fiber rate on strength improvement of cementitious filling composites

Abstract

The underhand cut-fill backfill mining manner (UCFBMM) is widely employed in nonferrous metallic mines, and stability of the artificial backfill top plate directly determines the safety of operators and equipment, which puts forward higher requirements on fill's bending properties. The purpose of the current research is to advance steel-fiber reinforced cemented tailings backfills’ (SFCTBs’) mechanical features by employing steel fibers. 17 groups of specimens were prepared by considering the effects of diverse steel fiber doping and magnetic induction strength on SFCTB's bending properties. Steel fiber reinforced SFCTB's bending evolution was studied by utilizing three-point bending tests, SEM interpretations, and X-ray computed tomography. Lab findings exhibited that directional distribution of steel fibers was effective in increasing SFCTB's flexural strength, and the flexural strength was positively correlated with fiber doping and magnetic induction strength. The presence of steel fibers and their directional distribution well inhibited crack development, and thus the crack resistance and toughness of SFCTBs, enabling them to bear greater tensile force. The unadulterated steel fiber reinforced SFCTBs showed sudden fracture when reaching the peak load, while the steel fiber adducted SFCTB specimens showed the characteristics of good ductility. Due to gravity and magnetism, steel fibers were distributed at the bottom of SFCTBs and showed a directional distribution along the length of the specimens. Besides, SFCTBs produced further CSH-gels and Aft in process of hydration. The overall outcomes of the current study could run an academic guide to construction of artificial backfilling roofs in UCFBMM in terms of cost and operational stages.