Recycling of Mineral Solid Wastes in Backfill Road Materials: Technical and Environmental Investigations

Purpose The development of the circular economy of mineral solid wastes implies searching for new treatment methods to guaranty their chemical quality and technical properties. The aim of this study is to use mineral solid wastes including dredged sediments (SED), construction and demolition waste (CDW), and municipal solid waste from incinerator (MSWI) to obtain backfill road materials. Methods Granular mixtures were prepared using Talbot-Fuller-Thompson curves to optimize their packing density. Then, these road materials were submitted to geotechnical, mechanical, and environmental analyses to validate their conformity. Results The results highlighted that the partial substitution of sand by CDW and MSWI seems to be the best option to enhance the mechanical properties of road materials. The replacement of sand by ternary mixtures of SED, CDW, and MSWI allowed obtaining acceptable road materials without resorting to any treatments. Equilibrium batch leaching tests performed on road materials revealed that the behavior of Ba, Cr, Cu, Sb, and Zn is mainly related to raw material properties i.e. pH, mineralogy, and pollutant contents. Conclusions This study highlights the opportunity to replace natural aggregates with a wide variety of mineral solid wastes. However, it is recommended to pay attention to the modification of leaching behaviors of wastes after treatment and formulation.