The present study copes with the environmental impact assessment of municipal solid waste incineration bottom ashes (MSWI BA) re-used as aggregates in road construction. The methodology involves the following steps: characterization of bottom ashes (physical properties, chemistry and mineralogy), experiments at laboratory scale, field study and geochemical modeling. Quantitative data for trace elements in primary glasses obtained by Secondary Ions Mass Spectrometry (SIMS) microanalysis show that these glasses are likely a main sink for Zn. In the cemented calcite admixture, lead seems to be mainly sorbed on iron oxy-hydroxides according to SIMS imaging and Extanded X-ray Absorption Fines Structure analysis (EXAFS). Except for SO4, low concentrations and alkalinity have been measured in leachates from a 10~year-old road built with MSWI BA (fast attenuation during the first years). No significant transformation of bottom ashes (such as an advanced carbonation state) has been observed after 10 years of utilization. Lateral preferential flowpaths (edge effects) are likely responsible for the difference between alcaline pore water and dilued leachates. Based on characterization and experimental data, an common model have been built to simulate leaching and mineralogical evolutions using the transport reactive code HYTEC. Simulations of batch and dynamic leaching tests, as well as of two roads (French and Swedish) built with bottom ashes show fair agreement with respect to the experimental data.
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