Curing stress effect on stability, microstructure, matric suction and electrical conductivity of cementitious tailings backfills

Abstract

Cementitious tailings backfill (CTB) is a regularly used technique for most mines at home and aboard since it has a significant meaning for the recycling of total tailings and enhances the safety of underground mines. Thus, studying the behavior of the CTB materials exposed to diverse curing stresses is fairly vital to guarantee the whole stability and long-term ageing of underground mining structures. This paper inspects the effect of diverse curing stresses (0 kPa – witness, 180 kPa, 360 kPa and 540 kPa) on physico-mechanical characteristics of CTB materials subjected to a curing age of up to 28 days. Based on lab tests, uniaxial compression and microstructure analyses are performed for all the specimens. To well characterize the self-desiccation behavior of CTB specimens, suction and electrical conductivity are also scrutinized during their curing processes. Results indicate that curing of CTBs under stress ranging from 0 to 540 kPa can improve their strength gains to some extent. Irrespective of curing stress, CTB’s suction is enlarged while its porosity is dropped once increased with curing age and stress, respectively. There exists a robust power function between suction and strength while there is a linear link between electrical conductivity and strength. One can state from this study that curing stress must be significantly taken into account during the backfill mixture proportions’ design.