Characterization flowchart for assessing the potential reuse of excavation soils in Sao Paulo city

Waste management solutions and reuse strategies for excavation soils from construction works are needed to increase the circularity of resources in urban areas. In this study, we assessed some reuse strategies for excavated soils, based on a geotechnical-environmental characterization study conducted with samples from an “inert” construction and demolition waste (CDW) landfill in Sao Paulo city. The geotechnical reuse of soil samples should be limited to applications where the material is confined (backfilling trenches, containing walls etc.), because of swelling and loss of bearing capacity after saturation. In addition, CDW-soil mixtures can be used in reinforcement of subgrades and sub-bases of pavements of low-volume roads. Gypsum/cementitious materials in contact with the leakage of sanitary effluents might result in sulfate concentrations that restrict the reuse of CDW due to quality requirements of superficial waters, however, without posing a significant risk to human health. They might also degrade neighboring concrete foundations. A methodological flowchart to support reuse strategies of soils for urban areas was proposed, based on current characterization tests.