Heavy metal dynamics of municipal solid waste ash as supplementary cementitious material

Combined with mechanical assessments, an environmental evaluation is vital to ensuring eco-friendly binder suitability. This study evaluates the environmental impact of integrating municipal solid waste incineration bottom ash into hydraulic road binders, alongside its physico-chemical, mechanical properties, and cementitious matrix hydration kinetics. Initial assessments of heavy metal concentrations in bottom ash revealed that copper (Cu) was leachable at 5.43 ± 0.042 mg/kg, and antimony (Sb) at 0.096 ± 0.006 mg/kg. After formulation, the leaching behavior of Cu and Sb became compliant with regulations. However sequential extraction analyses highlight notable dynamic changes in the distribution of Cu and Sb in the different fractions, underlining the instability of the matrix even in the absence of compliance alteration. Cu and Sb migrated from other fractions, eventually reaching their peak concentrations in the reducible fraction, at 78% for Cu and 64% for Sb, respectively. This underscores the necessity of integrating long-term environmental considerations alongside mechanical performance in sustainable infrastructure projects.