Sand-bentonite backfill amended with composite polymer exposed to organic acid: Hydraulic performance and microstructural properties

作者：Xian-Lei Fu, Zhe-Yuan Jiang, Jinkun Huang, Yan‐Jun Du · 发表于：Journal of Rock Mechanics and Geotechnical Engineering · 年份：2024 · DOI：10.1016/j.jrmge.2024.06.004 · 被引用次数：20 · 研究领域：Landfill Environmental Impact Studies、Grouting, Rheology, and Soil Mechanics、Materials Engineering and Processing

Soil-bentonite (SB) backfills in vertical cutoff walls are used extensively to contain contaminated groundwater. Previous studies show that the hydraulic conductivity of backfill can exceed the typically recommended maximum value (k = 1 × 10−9 m/s) if exposed to groundwater impacted by organic acids commonly released from uncontrolled landfills and municipal solid waste dumps. Polymer amended backfills exhibit excellent chemical compatibility to metal-laden groundwater. However, few studies to date have explored the effect of organic acid contaminated groundwater on hydraulic performance of polymer amended backfills. This study presents an experimental investigation on the hydraulic performance and microstructural properties of a composite polymer amended backfill used to contain flow of acetic acid-laden groundwater. A series of laboratory experiments were performed to evaluate free-swell indices of the composite polymer amended bentonites, liquid limits of the composite polymer amended and unamended bentonites, and slump heights and hydraulic conductivity (k) values of the amended backfills to acetic acid solutions with varying concentrations. The results were compared with those of the unamended bentonites and unamended backfills reported in a previous study. The results showed that the free-swell index and liquid limit of the amended bentonites were higher than those of the unamended bentonites. Permeation with acetic acid solutions with concentrations ranging from 40 mmo...