Relating monolithic and granular leaching from contaminated soil treated with different cementitious binders

Abstract

This work employed a clayey, silty, sandy gravel contaminated with a mixture of metals (Cd, Cu, Pb, Ni and Zn) and diesel. The contaminated soil was treated with 5 and 10% dosages of different cementitious binders. The binders include Portland cement, cement-fly ash, cement-slag and lime-slag mixtures. Monolithic leaching from the treated soils was evaluated over a 64-day period alongside granular leachability of 49- and 84-day old samples. Surface wash-off was the predominant leaching mechanism for monolithic samples. In this condition, with data from different binders and curing ages combined, granular leachability as a function of monolithic leaching generally followed degrees 4 and 6 polynomial functions. The only exception was for Cu, which followed the multistage dose-response model. The relationship between both leaching tests varied with the type of metal, curing age/residence time of monolithic samples in the leachant, and binder formulation. The results provide useful design information on the relationship between leachability of metals from monolithic forms of S/S treated soils and the ultimate leachability in the eventual breakdown of the stabilized/solidified soil.

Keywords:

• Blast furnace slag
• fly ash
• granular leaching
• lime
• monolithic leaching
• Portland cement

Acknowledgments

This article was written to support the ProCeSS project, which was conducted by a consortium of five universities, led by University College London, and 17 industrial partners, under the UK DIUS Technology Strategy Board (TP/3/WMM/6/I/15611). The project website is at http://www.cege.ucl.ac.uk/process.