Discussion on “Role of bentonite in improving the anti-seepage durability of fly ash-based geopolymer cutoff wall backfill under dry–wet cycles” by Chen et al., 2024
摘要
This communication endeavors to critically analyze the recently published article titled “Role of Bentonite in Improving the Anti-Seepage Durability of Fly Ash-Based Geopolymer Cutoff Wall Backfill Under Dry–Wet Cycles” by Hong-Xin Chen et al. in Acta Geotechnica (https://doi.org/10.1007/s11440-024-02446-1). The present discourse identifies several errors and limitations intrinsic to the use of bentonite-amended geopolymer vertical cutoff walls as presented by the authors. Notably, the inherent non-sealing properties of bentonites when subjected to high-concentration contaminants have been overlooked, despite their application in the study. Furthermore, the geomaterials employed were insufficiently characterized or omitted from the introductory context, leading to potential ambiguities in understanding their roles. Chen et al. have focused on a rigid geopolymer system for cutoff wall applications, neglecting the advantages of utilizing flexible slurry-based alternatives. Additionally, the critical aspect of diffusion characteristics within the cutoff wall is inadequately addressed. The reported hydraulic conductivity threshold of 10–8 m/sec as a criterion for cutoff wall effectiveness is deemed misleading; our analysis reveals that contaminant migration profiles, utilizing this hydraulic conductivity value, exhibit significant attenuation only within the initial two-year period. In light of this evidence, the discussion advocates for a more stringent hydraulic conductivity limit of 10–9 m/sec or lower to enhance the reliability of cutoff wall performance in contaminated environments.