Effect of hydraulic binders' addition on trace metals stabilization in the S/S process of dredged sediments.

The Solidification/Stabilization method for dredged sediments remediation can be very effective for the immobilization of trace metal (TM) pollutants. The ordinary Portland cement (OPC) is largely used in this process. Nevertheless, the mechanical performance of treated sediments can be considerably improved at long term using ground granulated blast furnace slag (GGBS) as was shown in (Gutsalenko et al., 2018). Therefore, it is worth investigating whether this new binder is also relevant in terms of stabilization and mechanisms involved in this process. To meet this objective, leaching test, total attack, sequential extraction (SE) and X-ray Adsorption Near-Edge Structure (XANES) experiments measurements were performed. The results of the leaching tests conducted as part of the study are promising for the use of GGBS in the treatment of the real case project Dublin sediment and it outperforms the OPC-based treatment.. The sequential extraction method was applied to evaluate the potential risks of toxic elements according to their repartition in the Dublin sediment matrix and predicts the release of metals under different environmental conditions. It shows a lower perturbation rate of pollutants with the GGBS-based binder. Finally, XANES experiments demonstrate changes in the chemical environment of Zn and Cu after the treatment of the sediment with OPC compared to the GGBS rich binder. Consequently, this study finds that it is more pertinent to use the GGBS-based binder in terms of trace metal stabilization.