Solidification/Stabilization (S/S) of High Concentration Zinc-Contaminated Soils Using Soda Residue
Solidification/stabilization (S/S) has been considered as one of the most effective techniques for remediation of the heavy metal-contaminated sites. Among various binders adopted in S/S, soda residue is extensively accepted and investigated due to its strong adsorptive capacity for heavy metal ions. In this paper, the engineering properties of the high concentration zinc-contaminated soil solidified/stabilized by soda residue blended with cement have been investigated. Test results showed that the unconfined compressive strength (UCS) of the treated specimen increased with the increase of the soda residue content and the curing time. A higher UCS can be obtained for specimens with lower zinc concentration. In toxicity characteristic leaching procedure (TCLP) test, the concentration of the leached heavy metal ions decreased with the increase of the curing time. Results of UCS and TCLP illustrated that cement-soda residue stabilized zinc-contaminated soil satisfied the standard of strength and leachability when the mass ratio of cement to soda residue was 2 to 8. X-ray diffraction (XRD) analysis obviously showed the formation of the hydrated products such as CSH, CAH and Aft. Zinc ions can be immobilized by precipitating as Zn(OH)2 or incorporating with hydrates to form CaZn2(OH)6H2O.
KeywordsStabilization/solidification Zinc-contaminated soil Soda residue Unconfined compressive strength Leachability
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