@article{WANG2026, 
author = {He WANG and Qing-yang DENG and Yu CHENG and Xiao WANG and Li-jie CHEN},
title = {Durability and leachability of solidified lead-zinc red clay under acidic wet-dry cycles},
year = {2026},
journal = {Rock and Soil Mechanics},
volume = {47},
number = {9},
pages = {2966-2982},
keywords = {dry-wet cycles, acid environment, solidification/stabilization, Pb2+/Zn2+-contaminated red clay},
url = {https://www.sciopen.com/article/10.26599/RSM.2025.94300373},
doi = {10.26599/RSM.2025.94300373},
abstract = {Soil heavy metal (HM) contamination is a widespread and serious environmental challenge. Even after treatment, contaminated soil may still pose a risk of secondary metal release under complex environmental conditions. In this study, a novel solidifying agent, a diatomaceous earth–fly ash-based geopolymer (D-FA), was synthesized from phosphoric acid (H3PO4), fly ash, and diatomaceous earth for the solidification/stabilization of contaminated lead-zinc red clay. Under coupled acid exposure and wet–dry cycling conditions, short-term effectiveness was evaluated using the toxicity characterization leaching procedure (TCLP), whereas the accelerated TCLP (ATCLP) was applied to analyze leaching kinetics and predict long-term performance. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and X-ray diffraction (XRD) were employed to characterize microstructural evolution and degradation mechanisms across multiple scales. A durability assessment framework based on cumulative leaching fraction (CFL) and effective diffusion coefficient (De) was established to predict the environmental safety period. The results showed that D-FA increased the strength of red clay by 6.59-fold and achieved fixation efficiencies of 99.99% for Pb2+ and 73.95% for Zn2+ within 28 days. Under long-term acid exposure and wet–dry cycling conditions, D-FA exhibited greater stability and durability in immobilizing Zn2+ than Pb2+. According to predictions based on Fick’s diffusion model, the environmental safety period reaches several decades for farmland at pH=5, exceeds 200 a for grassland and forest land, and may extend to several centuries for construction sites.}
}