Contessi, S., L. Calgaro, M.C. Dalconi, M. Secco, G. Ferrari, and G. Artioli.
REMEDIATE International Conference, 19-20 Sep 2018, Queen's University, Belfast. 34 slides, 2018

The high-performance solidification/stabilization (HPSS) process follows the principles of traditional S/S techniques, with the innovation of including a granulation step at the end of the process by using additives to produce cementitious granular materials. These pellets, characterized by low porosity and reduced leaching, could be reused as filling materials directly in the reclaimed area. The case study deals with the remediation of a former agriculture supply cooperative located in Bagnolo Mella, Italy, where the soil contains heavy metals. Pb poses special concerns for its high concentration and mobility, the latter enhanced in the alkaline conditions induced by the binder. This study aims for understanding at the molecular and microstructural level the immobilization mechanisms controlling Pb retention. Results indicate that Pb-containing soil minerals dissolve during the S/S process, leaving Pb dispersed within the cementitious matrix. By curing pellets in water with CO₂ addition, Pb leaching falls dramatically thanks to the lower pH and to the precipitation onto the pellet of an external layer of calcium carbonate. An additional step of water conditioning is proposed to improve binder maturation during the HPSS process and provide for a wider range of elements treated. Slides: http://www.remediate.eu/research-centres/Remediate/RemediateFilestore/Conference2018/Filetoupload,846344,en.pdf