An evaluation of stabilised/solidified contaminated model soil using PC-based and MgO-based binders under semi-dynamic leaching conditions

The leaching performance of stabilised/solidified contaminated model soil was studied to investigate the benefit of stabilisation/solidification treatment using novel binders over conventional binders. Different combinations of Portland cement (PC), ground granulated blast-furnace slag (GGBS), pulverised fly ash (PFA), and magnesia (MgO) were used and grouped into PC-based and MgO-based binders. A semi-dynamic leaching test was used, where the cumulative releases of Zn, Cu, Ni, Pb, Ca, and Mg were measured and the effective diffusion coefficients (De) and the leachability indices (LX) were calculated. The effects of different binders and water/cement ratios (w/c) on the migration of different metals after treatment were also discussed. The results showed that w/c ratio has a significant impact on the cumulative leachability of heavy metals. The diffusion coefficients of Pb and Zn are higher than those of Cu and Ni. In addition, mixes (w/c at 0.5:1) showed better performance in immobilising heavy metals than mixes (w/c at 1:1), especially in the case of Cu, Ni, and Pb