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Consolidation and hydraulic conductivity of zeolite-amended soil-bentonite backfills / Catherine S. Hong in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 1 (Janvier 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 1 (Janvier 2012) . - pp. 15-25 Titre : Consolidation and hydraulic conductivity of zeolite-amended soil-bentonite backfills Type de document : texte imprimé Auteurs : Catherine S. Hong, Auteur ; Charles D. Shackelford, Auteur ; Michael A. Malusis, Auteur Année de publication : 2012 Article en page(s) : pp. 15-25 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Bentonite  Consolidation  Cutoff  wall  Hydraulic  conductivity  Soil-bentonite  backfill  Zeolite Résumé : The effect of zeolite amendment for enhanced sorption capacity on the consolidation behavior and hydraulic conductivity, k, of a representative soil-bentonite (SB) backfill for vertical cutoff walls was evaluated via laboratory testing. The consolidation behavior and k of test specimens containing fine sand, 5.8% (dry weight) sodium bentonite, and 0, 2, 5, or 10% (dry weight) of one of three types of zeolite (clinoptilolite, chabazite-lower bed, or chabazite-upper bed) were measured using fixed-ring oedometers, and k also was measured on separate specimens using a flexible-wall permeameter. The results indicated that addition of a zeolite had little impact on either the consolidation behavior or the k of the backfill, regardless of the amount or type of zeolite. For example, the compression index, Cc, for the unamended backfill specimen was 0.24, whereas values of Cc for the zeolite-amended specimens were in the range 0.19 ≤ Cc ≤ 0.23. Similarly, the k for the unamended specimen based on flexible-wall tests was 2.4×10-10  m/s, whereas values of k for zeolite-amended specimens were in the range 1.2×10-10 ≤ k ≤ 3.9×10-10  m/s. The results of the study suggest that enhancing the sorption capacity of typical SB backfills via zeolite amendment is not likely to have a significant effect on the consolidation behavior or k of the backfill, provided that the amount of zeolite added is small ( ≤ 10%). DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v138/i1/p15_s1?isAuthorized=no [article] Consolidation and hydraulic conductivity of zeolite-amended soil-bentonite backfills [texte imprimé] / Catherine S. Hong, Auteur ; Charles D. Shackelford, Auteur ; Michael A. Malusis, Auteur . - 2012 . - pp. 15-25. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 1 (Janvier 2012) . - pp. 15-25 Mots-clés : Bentonite  Consolidation  Cutoff  wall  Hydraulic  conductivity  Soil-bentonite  backfill  Zeolite Résumé : The effect of zeolite amendment for enhanced sorption capacity on the consolidation behavior and hydraulic conductivity, k, of a representative soil-bentonite (SB) backfill for vertical cutoff walls was evaluated via laboratory testing. The consolidation behavior and k of test specimens containing fine sand, 5.8% (dry weight) sodium bentonite, and 0, 2, 5, or 10% (dry weight) of one of three types of zeolite (clinoptilolite, chabazite-lower bed, or chabazite-upper bed) were measured using fixed-ring oedometers, and k also was measured on separate specimens using a flexible-wall permeameter. The results indicated that addition of a zeolite had little impact on either the consolidation behavior or the k of the backfill, regardless of the amount or type of zeolite. For example, the compression index, Cc, for the unamended backfill specimen was 0.24, whereas values of Cc for the zeolite-amended specimens were in the range 0.19 ≤ Cc ≤ 0.23. Similarly, the k for the unamended specimen based on flexible-wall tests was 2.4×10-10  m/s, whereas values of k for zeolite-amended specimens were in the range 1.2×10-10 ≤ k ≤ 3.9×10-10  m/s. The results of the study suggest that enhancing the sorption capacity of typical SB backfills via zeolite amendment is not likely to have a significant effect on the consolidation behavior or k of the backfill, provided that the amount of zeolite added is small ( ≤ 10%). DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v138/i1/p15_s1?isAuthorized=no

Consolidation of a geosynthetic clay liner under isotropic states of stress / Jong-Beom Kang in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 1 (Janvier 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 253-259 Titre : Consolidation of a geosynthetic clay liner under isotropic states of stress Type de document : texte imprimé Auteurs : Jong-Beom Kang, Auteur ; Charles D. Shackelford, Auteur Article en page(s) : pp. 253-259 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Compressibility  Consolidation  Geosynthetic  clay  liner  Hydraulic  conductivity Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The consolidation behavior of a geosynthetic clay liner (GCL) was evaluated by consolidating duplicate specimens of the GCL in a flexible-wall cell to a final effective stress, sigma[prime], of 241 kPa (35.0 psi). The hydraulic conductivity, k, also was measured at the end of each loading increment. The results indicated that the GCL was normally consolidated for values of sigma[prime] greater than 34.5 kPa (5.0 psi), which correlates well with limited consolidation data reported in the literature for GCLs based on confined compression using oedometers. Values of the coefficient of consolidation, cv, for the GCL ranged from 5.2×10−10 m2/s to 2.1×10−9 m2/s, and generally decreased with increasing sigma[prime], albeit only slightly. Values of the measured k, kmeasured, for the GCL were low (<=5.0×10−9 cm/s) due to the sodium bentonite content of the GCL, and were within a factor of about two of the values of k calculated on the basis of classic (Terzaghi) small-strain consolidation theory, ktheory (i.e., 0.5<=ktheory/kmeasured<=2.0), suggesting that the theory is appropriate for describing the consolidation behavior of the GCL. The results also are consistent with the results of previous studies based on one-dimensional consolidation of sodium montmorillonite, suggesting that there would be little difference in the consolidation behavior of the GCL under confined compression. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...] [article] Consolidation of a geosynthetic clay liner under isotropic states of stress [texte imprimé] / Jong-Beom Kang, Auteur ; Charles D. Shackelford, Auteur . - pp. 253-259. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 1 (Janvier 2010) . - pp. 253-259 Mots-clés : Compressibility  Consolidation  Geosynthetic  clay  liner  Hydraulic  conductivity Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The consolidation behavior of a geosynthetic clay liner (GCL) was evaluated by consolidating duplicate specimens of the GCL in a flexible-wall cell to a final effective stress, sigma[prime], of 241 kPa (35.0 psi). The hydraulic conductivity, k, also was measured at the end of each loading increment. The results indicated that the GCL was normally consolidated for values of sigma[prime] greater than 34.5 kPa (5.0 psi), which correlates well with limited consolidation data reported in the literature for GCLs based on confined compression using oedometers. Values of the coefficient of consolidation, cv, for the GCL ranged from 5.2×10−10 m2/s to 2.1×10−9 m2/s, and generally decreased with increasing sigma[prime], albeit only slightly. Values of the measured k, kmeasured, for the GCL were low (<=5.0×10−9 cm/s) due to the sodium bentonite content of the GCL, and were within a factor of about two of the values of k calculated on the basis of classic (Terzaghi) small-strain consolidation theory, ktheory (i.e., 0.5<=ktheory/kmeasured<=2.0), suggesting that the theory is appropriate for describing the consolidation behavior of the GCL. The results also are consistent with the results of previous studies based on one-dimensional consolidation of sodium montmorillonite, suggesting that there would be little difference in the consolidation behavior of the GCL under confined compression. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...]

Hydraulic conductivity of bentonite slurry mixed sands / David Castelbaum in Journal of geotechnical and geoenvironmental engineering, Vol. 135 N° 12 (Décembre 2009) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1941–1956 Titre : Hydraulic conductivity of bentonite slurry mixed sands Type de document : texte imprimé Auteurs : David Castelbaum, Auteur ; Charles D. Shackelford, Auteur Année de publication : 2010 Article en page(s) : pp. 1941–1956 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : BentoniteHydraulic  conductivitySandSoil  typeSlurriesSoil  mixing Résumé : The hydraulic conductivity (k) of specimens from columns containing initially dry sands mixed with bentonite slurries was measured. The mixed specimens represented a range in void ratios (0.672≤e≤3.94) and bentonite contents ( 0.61%≤BC≤7.65% , by dry weight). The measured k values, which ranged from 2.4×10−7 cm/s to 6.8×10−4 cm/s , correlated poorly with the total void ratio (e) of the specimens, due to the complicating effect of the bentonite in the sand-bentonite slurry mixtures. However, the measured k values correlated better with the void ratio of the bentonite (eb) , which is consistent with the results of previous studies involving permeation of compacted bentonite and sand-bentonite specimens, even though the range in values of eb in this study (42.5≤eb≤127) was much higher than that previously reported. The relatively large range in eb values for the sand-bentonite slurry mixtures was also consistent with the relatively large range in measured k values, which are about one to seven orders of magnitude higher than values of k commonly reported for compacted sand-bentonite mixtures, despite similar bentonite contents. In terms of bentonite content, addition of more than 3% bentonite via slurry injection and mixing with the sands was successful in reducing the k of the unmixed sands (9.4×10−3 cm/s≤k≤5.4×10−2 cm/s) by as much as four orders of magnitude to values less than 1.0×10−6 cm/s . En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000169 [article] Hydraulic conductivity of bentonite slurry mixed sands [texte imprimé] / David Castelbaum, Auteur ; Charles D. Shackelford, Auteur . - 2010 . - pp. 1941–1956. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 135 N° 12 (Décembre 2009) . - pp. 1941–1956 Mots-clés : BentoniteHydraulic  conductivitySandSoil  typeSlurriesSoil  mixing Résumé : The hydraulic conductivity (k) of specimens from columns containing initially dry sands mixed with bentonite slurries was measured. The mixed specimens represented a range in void ratios (0.672≤e≤3.94) and bentonite contents ( 0.61%≤BC≤7.65% , by dry weight). The measured k values, which ranged from 2.4×10−7 cm/s to 6.8×10−4 cm/s , correlated poorly with the total void ratio (e) of the specimens, due to the complicating effect of the bentonite in the sand-bentonite slurry mixtures. However, the measured k values correlated better with the void ratio of the bentonite (eb) , which is consistent with the results of previous studies involving permeation of compacted bentonite and sand-bentonite specimens, even though the range in values of eb in this study (42.5≤eb≤127) was much higher than that previously reported. The relatively large range in eb values for the sand-bentonite slurry mixtures was also consistent with the relatively large range in measured k values, which are about one to seven orders of magnitude higher than values of k commonly reported for compacted sand-bentonite mixtures, despite similar bentonite contents. In terms of bentonite content, addition of more than 3% bentonite via slurry injection and mixing with the sands was successful in reducing the k of the unmixed sands (9.4×10−3 cm/s≤k≤5.4×10−2 cm/s) by as much as four orders of magnitude to values less than 1.0×10−6 cm/s . En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000169

Membrane behavior of compacted clay liners / Jong-Beom Kang in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 10 (Octobre 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 10 (Octobre 2010) . - pp. 1368-1382 Titre : Membrane behavior of compacted clay liners Type de document : texte imprimé Auteurs : Jong-Beom Kang, Auteur ; Charles D. Shackelford, Auteur Année de publication : 2010 Article en page(s) : pp. 1368-1382 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Bentonite  Clay  liners  Compacted  soils  Seepage  Chemico-osmosis  Clay  membranes Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The containment function of clay barriers used for waste containment applications (e.g., landfills) can be enhanced if such clays exhibit membrane behavior or the ability to restrict the migration of solutes (e.g., contaminants). In this regard, compacted specimens of a locally available natural clay known as Nelson Farm Clay (NFC), as well as NFC amended with 5% (dry weight) sodium bentonite, were evaluated for hydraulic conductivity, k, and the potential for membrane behavior. The membrane efficiencies of specimens of both soils compacted such that k was less than 10−7 cm/s were measured by establishing steady salt (KCl) concentration differences, −DeltaCo, ranging from 3.9 to 47 mM across the specimens in a flexible-wall cell under closed-system boundary conditions. The measured membrane efficiency for the unamended NFC was negligible (i.e., <=1.4%), even though the k was suitably low (i.e., k<10−7 cm/s). In contrast, compacted specimens of the bentonite amended NFC exhibited not only lower k but also significant membrane behavior, with membrane efficiencies as high as 97.3% for −DeltaCo of 3.9-mM KCl. The results suggest that natural clays typically suitable for use as compacted clay liners (CCLs) are not likely to behave as semipermeable membranes unless the clay is amended with bentonite or the clay is inherently rich in high swelling clay minerals (e.g., sodium smectite). The potential benefit resulting from membrane behavior in a CCL constructed with the bentonite amended NFC is illustrated analytically in terms of liquid flux. DEWEY : 624.1 ISSN : 1090-1241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...] [article] Membrane behavior of compacted clay liners [texte imprimé] / Jong-Beom Kang, Auteur ; Charles D. Shackelford, Auteur . - 2010 . - pp. 1368-1382. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 10 (Octobre 2010) . - pp. 1368-1382 Mots-clés : Bentonite  Clay  liners  Compacted  soils  Seepage  Chemico-osmosis  Clay  membranes Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The containment function of clay barriers used for waste containment applications (e.g., landfills) can be enhanced if such clays exhibit membrane behavior or the ability to restrict the migration of solutes (e.g., contaminants). In this regard, compacted specimens of a locally available natural clay known as Nelson Farm Clay (NFC), as well as NFC amended with 5% (dry weight) sodium bentonite, were evaluated for hydraulic conductivity, k, and the potential for membrane behavior. The membrane efficiencies of specimens of both soils compacted such that k was less than 10−7 cm/s were measured by establishing steady salt (KCl) concentration differences, −DeltaCo, ranging from 3.9 to 47 mM across the specimens in a flexible-wall cell under closed-system boundary conditions. The measured membrane efficiency for the unamended NFC was negligible (i.e., <=1.4%), even though the k was suitably low (i.e., k<10−7 cm/s). In contrast, compacted specimens of the bentonite amended NFC exhibited not only lower k but also significant membrane behavior, with membrane efficiencies as high as 97.3% for −DeltaCo of 3.9-mM KCl. The results suggest that natural clays typically suitable for use as compacted clay liners (CCLs) are not likely to behave as semipermeable membranes unless the clay is amended with bentonite or the clay is inherently rich in high swelling clay minerals (e.g., sodium smectite). The potential benefit resulting from membrane behavior in a CCL constructed with the bentonite amended NFC is illustrated analytically in terms of liquid flux. DEWEY : 624.1 ISSN : 1090-1241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&ONLINE=YES&s [...]