This study aims to improve the chemical stability and engineering performance of bentonite slurry used in slurry trench cutoff walls, which often suffers from reduced swelling and permeability when exposed to saline environments. To address this, five superabsorbent polymers-polyanionic cellulose (PAC), hydroxypropyl methylcellulose (HPMC), carboxymethyl starch sodium (CMS), xanthan gum (XG), and sodium polyacrylamide (Na-PAM), were evaluated as additives to enhance unamended bentonite (CB). Key performance indicators including swell index, Marsh viscosity, filtrate loss, and hydraulic conductivity were systematically measured in CaCl 2 solutions (0–100 mM). Results show that XG-amended bentonite (XB) significantly outperforms CB, achieving higher swell index (24.2 vs. 15.9 mL/2 g) and liquid limit (403% vs. 267%), while maintaining low filtrate loss and acceptable viscosity under saline conditions. Hydraulic conductivity tests indicate a 75.3% reduction in permeability for XB filter cakes compared to CB. Additionally, polymer performance varies with cation type, with Pb 2+ causing more severe degradation than Ca 2+ due to pH effects. The study demonstrates that polymer amendments, particularly XG, can effectively enhance bentonite performance in saline environments, providing practical guidance for the design and construction of durable slurry trench cutoff walls.
Shen et al. (Fri,) studied this question.