Performance evaluation of solidification/stabilization of dredged sediment using alkali-activated slag

Fine dredged sediment was immobilized using ground granulated blast furnace slag as a new binder for supplementary cementitious materials in a 3.5% NaOH solution to study its solidification/stabilization (S/S) and uses in various industrial applications. The aim of this study is to compare effect of mixing conditions of the saturated-surface-dry of dredged sediment to determine the proper mixing method in the S/S process. Measurements of mechanical strength, heavy metal leachability, and microstructural characterization of the dredged sediment treated with alkali-activated slag (AAS) paste were carried out. The maximum value of the mechanical strength was obtained when the same amount of the NaOH solution as the saturated-surface-dry of the dredged sediment was added. The leaching experiment results showed that heavy metals were immobilized in the AAS paste, and that Cr, Cd, and Pb were not detected. The results of the analysis indicate the relationship between mechanical strength and (Ca + Na)/(Si + Al) ratio. This study demonstrates the possibility of successfully using fine dredged sediment as a base aggregate or a sub-base material for concrete production.