Low-carbon binders produced from waste glass and low-purity metakaolin for cemented paste backfill

Abstract

Cemented paste backfill (CPB) favors the sustainable development of the mining industry. However, the lack of low-cost and low-carbon cementitious materials limits the large-scale application of CPB. Besides, the unreasonable disposal of waste glass (WG) leads to resources wasting and environmental pollution. The present work is dedicated to researching a cheaper and green binder using alkali-activated WG supplemented by low-grade metakaolin (MK) and calcined quarry dust (CQD). Adding both MK and CQD promoted the binder hydration, with accelerated setting and enhanced mechanical strength, but reduced flowability was noticed. X-ray diffraction analysis (XRD) and thermogravimetric (TG) analysis suggested that the main reaction gels were sodium aluminosilicate hydrate (N-A-S-H), calcium silicate hydrates (C-S-H), and hydrotalcite-like (Ht) phases. Cost and carbon analysis suggested the binder in this study was cheaper and greener than the OPC-based binder.