Abstract
Cemented paste backfill has become the standard in modern cut-and-fill and long-hole stoping mines globally. It has proven to be an efficient method in maximizing ore recovery while reusing up to 50% of the tailings for underground stope fill. To reach the required fill strength, paste backfill must incorporate a cementitious binder. The cost of this binder can account for up to 75 to 80% of the total backfilling cost. Therefore, reducing the binder content can generate substantial savings while reducing cement related CO2 emissions. The loss in strength due to binder reduction can be compensated by paste backfill admixtures, which allow an increase in the paste solid content while maintaining a flowable paste. This study analyses cemented paste backfill mixes sourced from three different Canadian hard rock mines. Laboratory results validate significant binder reduction by changing the paste mix designs. The use of customized cement-reducing admixtures results in a paste solid content increase, ranging from 3 to 4%. This, in turn, facilitates a total binder reduction of 14 to 26%. This binder reduction translates to a reduction in CO2eq per kilogram of paste, ranging from 4 to 26%.