Alternative by-product based binders for cemented mine backfill: Recipes optimisation using Taguchi method

In this paper, four pozzolanic by-products (waste glass, copper slag, wood bottom ash and coal fly ash) and two by-products (cement kiln dust (CKD) and anhydrite) having hydration activating potential are mixed with Portland cement and ground granulated blast-furnace (GGBS) to create low cost binders to be used in mine cemented paste backfill (CPB). The Taguchi method is used to optimise binders’ formulations in regard of mechanical strength development. Two series of experiments are implemented: optimisation tests on CPB prepared with pure silica and validation experiments on CPB prepared with real mine tailings. ly, between 35% and 45% of expensive binders (Portland cement and GGBS) can be substituted by by-products (pozzolan and activator). Waste glass and copper slag are respectively the most and the least performing pozzolanic by-products and Wood bottom ash and coal fly ash have an intermediate cementitious potential. Nevertheless, their reactivity is insufficient to compete with GGBS which content can be adjusted to reach the strength required by mine exploitation. The strength development can be accelerated by substituting up to 30% of Portland cement by anhydrite, adding 5% of CKD and slightly increasing the amount of pozzolan.