Stabilisation of a dredged marine sediment: geotechnical and contaminant leaching properties

Abstract

In this paper, contaminated sediment dredged from a commercial harbour in Ireland was stabilized using Ordinary Portland cement (OPC) alone and in combination with Ground Granulated Blast Furnace Slag (GGBS). The engineering characteristics of the stabilized sediments were established from Unconfined Compression Strength tests. Tank leaching tests were conducted to investigate the long term release of 11 elements (Al, Cr, Mn, Fe, Ni, Cu, Zn, As, Cd, Ba, Pb) relative to their original concentrations in the stabilized sediment. Leached concentrations after 100 days were below 1% of the original concentration for most elements. Cement replacement with suitable amounts of GGBS increased stabilized strength and also decreased the extent of leaching of Al, Cr, Mn, Fe, Ni, Cu and Pb. The performance of OPC alone was superior for restricting leaching of Zn, Cd and As. Both Al and Fe are key elements in the stabilization process; the results suggest that Al stabilizes more slowly than Fe. Given that GGBS is both a more cost-effective and more environmentally-friendly material than OPC and that it is commonly used in concrete, its potential for stabilization of sediments warrants further study.