Influence of temperature on compressive strength, microstructure properties and failure pattern of fiber-reinforced cemented tailings backfill

Abstract

With the increase of mining depth, the geothermal temperature in deep stopes has becomes one of the significant factors affecting the mechanical strength and stability of cemented tailings backfill (CTB). This experimental study investigates the influence of curing temperature (20, 35 and 50 °C) on compressive strength, microstructure properties and failure pattern of fiber-reinforced cemented tailings backfill (FCTB). A series of unconfined compressive strength (UCS) and microstructural tests were conducted on FCTB specimens that are cured for 3, 7 and 28 days and prepared with different polypropylene (PP) fiber content (0.00%, 0.05%, 0.15%, 0.25% by the total mass of tailings and cement), respectively. The obtained results show that PP fibers and curing temperature effectively improve the unconfined compressive strength (UCS) of FCTB. The UCS values increase with the increase of fiber content, but decreases when there is 0.15% fibers by weight regardless of curing temperature. For a given fiber content, a higher temperature results in decreased porosity, thus the strength of FCTB specimens is increased. Moreover, fibers result in the transformation of the FCTB specimens from a relatively brittle to ductile failure state, which contributes to the mechanical stability of CTB structure. And, with higher fiber content, the brittleness of the FCTB specimens is reduced and ductility enhanced obviously. Mixing fibers can retard the propagation of cracks, constrain the deformation and improve the integrity of CTB structure, and thereby prevent ore dilution induced by the destabilization failure backfill in field stope, which provides a potentially economic method to reduce ore dilution for deep mines.