{"title":"Mechanisms controlling the hydraulic conductivity of anionic polymer-enhanced GCLs","authors":"A. Norris, Joseph Scalia IV, C. Shackelford","doi":"10.1680/jgein.21.00051","DOIUrl":null,"url":null,"abstract":"The hydraulic conductivity (k) of specimens of enhanced-bentonite geosynthetic clay liners (EB-GCLs) comprising anionic polymers permeated with concentrated salt solutions, i.e., 500 mM NaCl and 167 mM CaCl2, was measured to determine the effects of polymer properties and specimen preparation method on the k and the associated roles of polymer retention and elution in dictating the measured k. The results of hydrogel formation tests illustrated that poly(acrylic acid) hydrogel was formed in solutions tested during EB-GCL hydration. A dry sprinkling method of specimen preparation resulted in low k (≤ 5.5×10−11 m/s) in multiple EB-GCLs, with a low fraction (≤ 2.5 %) of retained polymer. In contrast, polymer elution from EB-GCLs prepared using a dry mixing method resulted in interaggregate seepage and an increase in k. Higher polymer retention occurred for the wet-mixed EB-GCLs, but did not directly correlate to low k. The long-term k of the EB-GCLs is dependent on several factors, including (i) formation of hydrogel, (ii) mobilization of hydrogel into and blocking of the most conductive pores, (iii) balance of seepage forces and hydrogel crosslink bond strength, (iv) kinetics of hydrogel formation, and (v) adsorption of polymer to the surfaces of the bentonite particles or aggregates of particles.","PeriodicalId":12616,"journal":{"name":"Geosynthetics International","volume":" ","pages":""},"PeriodicalIF":2.8000,"publicationDate":"2022-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"4","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Geosynthetics International","FirstCategoryId":"89","ListUrlMain":"https://doi.org/10.1680/jgein.21.00051","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, GEOLOGICAL","Score":null,"Total":0}
引用次数: 4
Abstract
The hydraulic conductivity (k) of specimens of enhanced-bentonite geosynthetic clay liners (EB-GCLs) comprising anionic polymers permeated with concentrated salt solutions, i.e., 500 mM NaCl and 167 mM CaCl2, was measured to determine the effects of polymer properties and specimen preparation method on the k and the associated roles of polymer retention and elution in dictating the measured k. The results of hydrogel formation tests illustrated that poly(acrylic acid) hydrogel was formed in solutions tested during EB-GCL hydration. A dry sprinkling method of specimen preparation resulted in low k (≤ 5.5×10−11 m/s) in multiple EB-GCLs, with a low fraction (≤ 2.5 %) of retained polymer. In contrast, polymer elution from EB-GCLs prepared using a dry mixing method resulted in interaggregate seepage and an increase in k. Higher polymer retention occurred for the wet-mixed EB-GCLs, but did not directly correlate to low k. The long-term k of the EB-GCLs is dependent on several factors, including (i) formation of hydrogel, (ii) mobilization of hydrogel into and blocking of the most conductive pores, (iii) balance of seepage forces and hydrogel crosslink bond strength, (iv) kinetics of hydrogel formation, and (v) adsorption of polymer to the surfaces of the bentonite particles or aggregates of particles.
期刊介绍:
An online only, rapid publication journal, Geosynthetics International – an official journal of the International Geosynthetics Society (IGS) – publishes the best information on current geosynthetics technology in research, design innovation, new materials and construction practice.
Topics covered
The whole of geosynthetic materials (including natural fibre products) such as research, behaviour, performance analysis, testing, design, construction methods, case histories and field experience. Geosynthetics International is received by all members of the IGS as part of their membership, and is published in e-only format six times a year.