Municipal solid waste incineration bottom ash recycling in concrete: Preliminary approach with Oporto wastes

The present research explored the feasibility of using dry finely ground bottom ash (GBA) from municipal solid waste incineration as SCM for concrete mixtures in cooperation with a local waste management company, LIPOR. A first study was performed using GBA as a sole partial replacement for Portland cement in paste and mortar specimens. GBA showed both beneficial and detrimental effects on paste/mortar mixtures. In terms of fresh properties, water demand on paste and workability on mortar containing GBA as cement replacement kept the same as reference specimens paste/mortars. Setting time was not affected by GBA incorporation, and ASR expansion was mitigated. The disadvantageous effect, namely, mechanical strength loss on GBA mortar, was mainly due to metallic aluminium, found on the main oxide composition and SEM of GBA, which is associated with hydrogen gas evolution. Thus, the amount of aluminium content remaining in MIBA should be analysed even after the ageing process.