Analysis of leaching procedures for environmental risk assessment of recycled aggregate use in unpaved roads

[Display omitted] ► Leaching assessment of seven recycled aggregates reused as subbase in unpaved road. ► Compliance, availability and percolation test results were related to each other. ► The materials were classified according the limit values of the Landfill Directive. ► A group composed by the most relevant pollutant metals was identified. The leaching behaviour of recycled materials from construction and demolition projects needs to be deemed acceptable before they are used for civil infrastructure. The study examines three leaching procedures for characterisation of the potential release of heavy metals and anions regulated by the EU Landfill Directive on seven recycled aggregates and two natural materials. The goal of the study is to relate the complex procedures designed for analysis of material leaching behaviour to quick leaching tests used for regulatory purposes. To integrate the data, results of the compliance test, availability test and percolation test were related to each other. The results revealed that two recycled aggregates (the asphaltic and a concrete material) could be classified as inert material and the remainder were categorised as non-hazardous. Finally, the statistical analysis conducted permitted the identification of the group of heavy metals which are close to their acceptance thresholds. Thus, the noticeable amounts of Ni, Cr, Sb, Zn and Cu warrant their consideration as relevant from an environmental point of view.