Effect of tailings fineness on the pore structure development of cemented paste backfill

- Generally, the total porosity increases with the increase in tailings fineness.
- The tailings fineness significantly affects the pore-size distribution.
- The filling effect reduces the critical pore diameter.

Cemented paste backfill (CPB) is an important engineering material nowadays. However, there is limited information about the influence of particle-size distribution on the pore structure properties of coarse tailings used in CPBs. This study investigates the effects of particle-size distribution on the pore-structure development of CPB samples. Therefore, this paper presents experimental results to assess the influence of the fineness of tailings on important parameters (total porosity, pore-size distribution, and critical pore diameter) cured for 7, 14, and 28 days. Mercury intrusion porosimetry tests are performed to provide insights into the pore structure of CPBs. Within the limits of this study, the total porosity and small pores (<10 μm) increased, whereas the critical pore diameter and large pores (>10 μm) decreased with the increase of tailings fineness. Furthermore, the influence of tailings fineness on the critical pore diameter decreased with extended curing time. Results show that the tailings fineness notably affected the pore structural properties of hardened CPBs.