Towards Cement Minimization and Circular Economy Recycling waste-to-energy bottom ash in construction

Abstract

The pursuit of carbon neutrality and the reduction of carbon dioxide (CO2) emissions have become key areas of focus in Sweden, especially within the construction sector. Cement production is recognized as one of the largest industrial contributors to CO2 emissions globally. To mitigate its environmental impact, ongoing research has fo cused on the partial replacement of cement with supplementary cementitious materials (SCMs). Among these alternatives, coal fly ash has been extensively studied; how ever, this project investigates the potential of bottom ash derived from Waste-to-Energy (WtE) which is processed to form Mineral Fraction of Icinerator Bottom Ash (MIBA) as a viable SCM. The MIBA used in this study was initially separated into different particle size fractions, which were subsequently processed to achieve a uniform parti cle size. Concrete cubes were then produced with a fixed level of SCM substitution. The compressive strength of these cubes was measured and compared to reference sam ples made with ordinary Portland cement to assess the mechanical performance of the material. The primary aim of this study is not only to assess the feasibility of substituting cement with bottom ash but also to evaluate the environmental implications of such substitution, particularly the leaching of potentially harmful metals from the resulting concrete. To achieve this, the leaching behavior of heavy metals from concrete cubes containing bot tom ash was investigated using a semi-dynamic leaching test (batch leaching method). The extent of metal release was quantified and analyzed using advanced analytical tech niques such as Inductively Coupled Plasma Mass Spectrometry (ICP-MS) and Powder X-Ray Diffraction (XRD). The findings contribute to understanding the environmental performance of bottom ash as an SCM and support its potential role in reducing CO2 emissions in the cement and construction industries.