Suitability assessment of chemically stabilized soil for utilization in constructions

Abstract

According to the EU Directive on the Landfill of Waste, a large number of old landfills should be closed and covered during the next few years. This requires millions of tonnes of construction materials. Secondary construction materials can reduce the consumption of virgin resources. Application of treatment techniques for contaminated soil, such as chemical stabilization, may allow utilisation of the treated soil as a secondary construction material. This work aims at evaluating the suitability of chemically stabilized soil to be used as a construction material for the final cover of a landfill from environmental as well as geotechnical points of view. Laboratory experiments were performed with chromated copper arsenate (CCA) contaminated soil. Iron-containing material (magnetite) was added to the soil at 15 wt% rate to reduce contaminant mobility. Soil pore water was sampled using Rhyzon soil moisture samplers and analysed to assess changes in soil chemical stability. To assess changes in mechanical properties, the hydraulic conductivity and porosity of untreated and treated soils were investigated. Soil treatment with Fe-containing amendments was most effective for reducing leaching of arsenic, but insufficient for copper and zinc. Iron amendments doubled the soil permeability. Unchanged leaching of Cu and Zn and increased permeability of the treated soil might not satisfy the requirements for the use of the material as liner in a landfill top cover. However, the treated soil might be considered for other parts of the construction, e g the protection layer.