Solidification/stabilization (S/S) is a widely adopted remediation technique for contaminated soils. However, how to efficiently and economically modify contaminated soil remains challenging. In this study, secondary aluminum ash slag (AAS) was employed as a novel stabilizer for the S/S treatment of lead (Pb) and zinc (Zn) contaminated soils. Two sample preparation methods (internal/external addition) were compared via unconfined compressive strength (UCS) and hydraulic conductivity tests. Toxicity characteristic leaching procedure (TCLP) tests were further conducted to evaluate the retention capacity of contaminated ions. Hereafter, microstructural characterizations, including scanning electron microscopy coupled with energy‐dispersive spectroscopy (SEM‐EDS) and mercury intrusion porosimetry (MIP) analyses, were performed to elucidate the stabilization mechanisms. Results show that moderate incorporation of AAS can significantly enhance both mechanical and stability behaviors. An optimal AAS dosage of 4% achieved a UCS exceeding 2000 kPa; the hydraulic conductivity and leaching concentration were also improved. Microstructural analysis indicated that external addition of AAS promoted the formation of calcium aluminosilicate hydrate (C‐A‐S‐H) and ettringite (AFt), enhancing compactness through pore filling. These findings demonstrate the potential of AAS as a sustainable and cost‐effective stabilizer for S/S treatment of contaminated soil.
Wang et al. (Thu,) studied this question.