Chemical analysis of contaminated soil strengthened by the addition of lime

Strengthening of contaminated materials using inorganic cementitious agents is becoming more widely used in the UK. The method has particular advantag es for bulk fill operations such as highway earthworks. Research has been d one into the chemical characteristics of leachates and leached solid sample s from a study into the long-term durability of a lime strengthened silt/pf a mixture amended with sewage sludge. This involved determinations of chemi cal composition and mineralogy, and geochemical modelling using MINTEQA2. N one of the heavy metals tested is present in the leachate at a concentratio n likely to pose a significant environmental threat, although some were pre sent to a higher degree than expected based on the inorganic chemistry. Thi s is ascribed to complexation of the heavy metals with dissolved organic ma tter. (C) 2001 Elsevier Science B.V. All rights reserved.