Effects of GGBS on the solidification/stabilization of port sediments contaminated with heavy metals

Abstract

The stability of heavy metal (HM) compounds contained in the Dublin port sediments solidified in different hydraulic binders was considered through leaching tests. Four different binders were considered: Portland cement (OPC), Portland cement-Granulated ground blast furnace slag (GGBS) (at two different GGBS contents), and a supersulfated mix. The leaching test results under initially neutral pH conditions indicated that the HM compounds were rather stable in the sediment. Surprisingly, addition of the binder led in general to the destabilization of the HM compounds. The OPC binder was found to be the most destabilizing binder. Increasing the amount of GGBS in the binder led to the decrease of the destabilization effect. This was correlated with the XAS (Synchrotron X-ray Absorption Spectroscopy) results, which showed that the chemical environment of Cu and Zn was not modified in the case of binders with high GGBS content. The time evolution of the compressive strength of the binder-sediment samples was also considered. Is was found that the strength of the GGBS-based samples increased with time, while those with plain OPC decreases significantly beyond 28 days.