Grain-size composition effect on flexural response and pore structure of cementitious tail-rock fills with fiber reinforcement

This paper explores the grain-size composition effect on flexural and micro-structural features of fiber reinforced cementitious tail-rock fill (FRCTRF). The FRCTRF mixes considered contained a stationary solid concentration of 70 wt% and a cement/tail rate of 1:6, and were cured for an age of 7-day for strength tests and microstructure. Three-point bending test shows that FRCTRF’s bending property is upgraded by totaling gravel rock. Adding fiber to FRCTRF’s bottom can enhance its peak deflection. With rising gravel particle size/dosage, FRCTRF’s peak deflection displays a trend of falling first and then growing. Accumulating polypropylene fiber could advance FRCTRF’s post-peak strength features as well. FRCTRF sample containing gravel has a large stress drop, and adding gravel rock could essentially boost FRCTRF’s post-peak brittle-ability. In conclusion, this study provides a strong scientific and theoretical underpinning for optimizing artificial false roofs employed recently in modern underground metalliferous mining operations.