MECHANICAL BEHAVIOUR OF CEMENTED PASTE BACKFILL

Cemented paste backfill is a method increasingly used by modern mines throughout the world due to increasingly stringent environmental regulations on sulfur -rich tailings. This paper studies the mechanical behavior of cemented paste backf ill with mid term (up to 91 days) and long term (more than 91 days) curing times. Two Canadian sulfur mine tailings samples were used for making various backfill mixtures with three different types of binder : Portland cement- based binder (PC), fly ash-based binder (FP) and slag-based binder (SP). The uniaxial compression test results showed that (qu)SP > (qu)FP ≈ (qu)PC. These tests also showed that for a given type of binder, the kinetics of hydration depends on the tailings properties while the obtained long-term strengths of the paste backfill are very similar. The triaxial compression test results demonstrate that both the cohesion of the backfill increases and the angle of friction decreases with an increase in the percentage of binder material.