Novel SCMs produced by the calcination of secondary aluminium dross with dolomite and their potential usage in cemented paste backfill

Abstract

In this study, novel supplementary cementitious materials (SCMs) were produced by the mixed calcination of secondary aluminium dross and dolomite. The thermal activation effect on calcined mixes, hydration properties of pastes with the novel SCMs and workability of cemented paste backfill (CPB) were experimentally investigated. The results demonstrated that high-temperature calcination evidently increased the activity of SCM, and the improvement by thermal activation was positively correlated with calcination temperature. Pastes with calcined SCMs hydrated to form more CsbndSsbndH, ettringite and Ht but less portlandite because of the accelerated pozzolanic reaction of SCMs. Moreover, CPB samples with novel SCM had an imporved transportation performance and mechanical strength with denser pore structure. Furthermore, heavy metals (Cu, Pb, Zn and Cr) were well-immobilised/stabilised by CPB with novel SCMs calcined at 900 °C and 1,000 °C, which can make secondary aluminium dross be used without environmental risks.