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

作　　者：Xian-Lei Fu Zhe-Yuan Jiang Jin-Kun Huang Yan-Jun Du 

机构地区：[1]Jiangsu Key Laboratory of Low Carbon and Sustainable Geotechnical Engineering,Institute of Geotechnical Engineering,Southeast University,Nanjing,210096,China [2]China MCC17 Group Co.,Ltd.,Maanshan,243000,China

出　　处：《Journal of Rock Mechanics and Geotechnical Engineering》2025年第4期2552-2565,共14页岩石力学与岩土工程学报(英文)

基　　金：National Natural Science Foundation of China (Grant No.42177133);Primary R&D Plan of Jiangsu Province (Grant No.BE2022830);Primary R&D Plan of Anhui Province (Grant No.2023t07020018).

摘　　要：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 mmol/L to 320 mmol/L conducted on the amended backfill only resulted in an increase in k of less than a factor of about 10 related to that based on permeation with tap water(4.41×10^(−11)-1.68×10^(−10) m/s to acetic acid solution versus 1.65×10^(−11) m/s to tap water).Mechanisms contributing to enhanced chemical compatibility of amended backfill were ascertained based on scanning electron microscopy,mercury intrusion porosimetry,and zeta potential analyses.

关 键 词：Acetic acid Hydraulic performance Hydroxypropyl methylcellulose(HPMC) Polyanionic cellulose(PAC) Soil-bentonite(SB)backfill 

分 类 号：TU411[建筑科学—岩土工程] TU443[建筑科学—土工工程]