Assessment of strength and leaching characteristics of heavy metal–contaminated soils solidified/stabilized by cement/fly ash

Solidification/stabilization technique has been widely adopted to remediate the heavy metal–contaminated sites. In the present work, the strength and leaching characteristics of the contaminated soils solidified/stabilized by cement/fly ash were systemically investigated. Electrical resistivity was also measured to establish empirical relationships for assessment of remediation efficacy. Tests results showed that the unconfined compressive strength increased and the leached ion concentration decreased with increasing curing time. In contrast, the unconfined compressive strength decreased and the leached ion concentration increased with increasing initial heavy metal ion concentration in the specimen. For the strength characteristic, the most notable detrimental effect was induced by Cr³⁺ and the least was induced by Pb²⁺. For the leaching characteristic, the trend was reversed. The electrical resistivity of the tested specimen increased significantly with increasing curing time and with decreasing initial ion concentration. The electrical resistivity of the Pb-contaminated specimen was higher than that of the Zn-contaminated specimen, which in turn was higher than that of the Cr-contaminated specimen. Empirical relationships between the strength, leaching characteristic, and electrical resistivity were established, which could be adopted to assess the remediation efficacy of heavy metal–contaminated soil solidified/stabilized by cement/fly ash.