Hydro-microstructural behaviors of zeolite/active carbon amended soil-bentonite cut-off wall

作者：Yong He, Shiyu Li, Zhao Zhang, Kao-fei Zhu, Wei He, Ke-neng Zhang · 发表于：Journal of Rock Mechanics and Geotechnical Engineering · 年份：2024 · DOI：10.1016/j.jrmge.2024.04.035 · 被引用次数：13 · 研究领域：Landfill Environmental Impact Studies、Soil and Unsaturated Flow、Grouting, Rheology, and Soil Mechanics

The soil-bentonite (SB) cut-off wall has been widely considered a vertical barrier to effectively control the migration of pollutants in contaminated sites. Recently, active porous materials have been used as a promising candidate amendment for mitigating chemical degradation and improving the retardation capacity of the SB cut-off wall. In this study, the silty clay from a typical Cr(VI) contaminated site was selected as the body material of the SB cut-off wall, and zeolite and active carbon were used as the modifiers of the silty clay-bentonite backfills, respectively. The impact of the two modifiers on the engineering properties of the backfills was investigated through a series of slump tests, consolidation tests, hydraulic conductivity tests, and microstructure tests. The experimental results demonstrated that the slump curves closely exhibited a linear relationship between standard slump and moisture content. Meanwhile, bentonite could improve the optimum moisture content of the backfills, while the addition of the two modifiers yielded the opposite outcome. As the bentonite content increased, the compression index of the backfills significantly increased, while the hydraulic conductivity decreased. At a given bentonite content of 5%, the addition of zeolite or active carbon resulted in a reduction in the compression index and initial void ratio, while exhibiting minimal impact on the hydraulic conductivity. Scanning electron microscope (SEM) observations indicated that...