Documents disponibles écrits par cet auteur

Biocalcification of sand through ureolysis / Chiung-Wen Chou in Journal of geotechnical and geoenvironmental engineering, Vol. 137 N° 12 (Décembre 2011) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1179-1189 Titre : Biocalcification of sand through ureolysis Type de document : texte imprimé Auteurs : Chiung-Wen Chou, Auteur ; Eric A. Seagren, Auteur ; Ahmet H. Aydilek, Auteur Année de publication : 2012 Article en page(s) : pp. 1179-1189 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Soil  properties  Bacteria  Calcium  carbonate  Strength Résumé : Biological processes may provide great and previously unexplored opportunities for cost-effective, in situ improvement of the engineering properties of soil. A laboratory study was conducted to evaluate the changes in geomechanical properties of sand attributable to the formation of calcium precipitates induced through ureolysis catalyzed by Sporosarcina pasteurii (S. pasteurii). Specifically, direct shear and California Bearing Ratio (CBR) tests were conducted on sand specimens subjected to treatment by growing, resting, and dead S. pasteurii cells in completely stirred tank reactors and completely mixed biofilm reactors, respectively. Scanning electron microscopy analyses were also conducted to evaluate microbially induced precipitation. The results of the study show that the bacterial cells effectively improved the geomechanical properties of the sand. Growing cells improved the sand properties owing to microbially induced precipitation and related pore volume changes, whereas dead and resting cells generally caused smaller increases in friction angle and bearing strength. Analysis of the sand from CBR specimens treated with growing cells demonstrated that the microbial and chemical processes both contributed to the clogging of the porous medium. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i12/p1179_s1?isAuthorized=no [article] Biocalcification of sand through ureolysis [texte imprimé] / Chiung-Wen Chou, Auteur ; Eric A. Seagren, Auteur ; Ahmet H. Aydilek, Auteur . - 2012 . - pp. 1179-1189. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 137 N° 12 (Décembre 2011) . - pp. 1179-1189 Mots-clés : Soil  properties  Bacteria  Calcium  carbonate  Strength Résumé : Biological processes may provide great and previously unexplored opportunities for cost-effective, in situ improvement of the engineering properties of soil. A laboratory study was conducted to evaluate the changes in geomechanical properties of sand attributable to the formation of calcium precipitates induced through ureolysis catalyzed by Sporosarcina pasteurii (S. pasteurii). Specifically, direct shear and California Bearing Ratio (CBR) tests were conducted on sand specimens subjected to treatment by growing, resting, and dead S. pasteurii cells in completely stirred tank reactors and completely mixed biofilm reactors, respectively. Scanning electron microscopy analyses were also conducted to evaluate microbially induced precipitation. The results of the study show that the bacterial cells effectively improved the geomechanical properties of the sand. Growing cells improved the sand properties owing to microbially induced precipitation and related pore volume changes, whereas dead and resting cells generally caused smaller increases in friction angle and bearing strength. Analysis of the sand from CBR specimens treated with growing cells demonstrated that the microbial and chemical processes both contributed to the clogging of the porous medium. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v137/i12/p1179_s1?isAuthorized=no

Sepiolite as an alternative liner material in municipal solid waste landfills / Yucel Guney in Journal of geotechnical and geoenvironmental engineering, Vol. 134 n°8 (Août 2008) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°8 (Août 2008) . - pp. 1166–1180 Titre : Sepiolite as an alternative liner material in municipal solid waste landfills Type de document : texte imprimé Auteurs : Yucel Guney, Auteur ; Savas Koparal, Auteur ; Ahmet H. Aydilek, Auteur Année de publication : 2008 Article en page(s) : pp. 1166–1180 Note générale : Geotechnical and geoenvironmental engineering Langues : Anglais (eng) Mots-clés : Municipal  wastes  Solid  wastes  Landfills  Adsorption  Inorganic  chemicals  Waste  management Résumé : Compacted clay has traditionally been used as a lining material in municipal solid waste landfills. However, natural clays may not always provide good contaminant sorption properties. One alternative material that is abundant in some parts of Europe and Turkey as well as Western United States is sepiolite. A laboratory study was undertaken to investigate the feasibility of sepiolite as a liner material. Two clays, one rich in sepiolite and the other one rich in kaolinite mineral, as well as their mixtures were subjected to geomechanical, hydraulic, and environmental tests. The same soils were also subjected to strength and hydraulic conductivity tests after a series of freeze and thaw cycles. The results of the study indicated that relatively high hydraulic conductivity and shrinkage capacity of sepiolite necessitates addition of kaolinite before being used as a landfill material. The valence of the salt solutions affected the swell and hydraulic conductivity characteristics of the clays tested. Retardation factors for sepiolite for metal solutions are 1.2–2.2 times higher than those calculated for the clay that is rich in kaolinite, and the inorganic contaminant adsorption capacity of the clay can be improved by addition of sepiolite. The results indicated that the clay mixtures utilized in this study provide good geomechanical, hydraulic, and metal adsorption properties which may justify their potential use as a liner material in solid waste landfills. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A8%2811 [...] [article] Sepiolite as an alternative liner material in municipal solid waste landfills [texte imprimé] / Yucel Guney, Auteur ; Savas Koparal, Auteur ; Ahmet H. Aydilek, Auteur . - 2008 . - pp. 1166–1180. Geotechnical and geoenvironmental engineering Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 134 n°8 (Août 2008) . - pp. 1166–1180 Mots-clés : Municipal  wastes  Solid  wastes  Landfills  Adsorption  Inorganic  chemicals  Waste  management Résumé : Compacted clay has traditionally been used as a lining material in municipal solid waste landfills. However, natural clays may not always provide good contaminant sorption properties. One alternative material that is abundant in some parts of Europe and Turkey as well as Western United States is sepiolite. A laboratory study was undertaken to investigate the feasibility of sepiolite as a liner material. Two clays, one rich in sepiolite and the other one rich in kaolinite mineral, as well as their mixtures were subjected to geomechanical, hydraulic, and environmental tests. The same soils were also subjected to strength and hydraulic conductivity tests after a series of freeze and thaw cycles. The results of the study indicated that relatively high hydraulic conductivity and shrinkage capacity of sepiolite necessitates addition of kaolinite before being used as a landfill material. The valence of the salt solutions affected the swell and hydraulic conductivity characteristics of the clays tested. Retardation factors for sepiolite for metal solutions are 1.2–2.2 times higher than those calculated for the clay that is rich in kaolinite, and the inorganic contaminant adsorption capacity of the clay can be improved by addition of sepiolite. The results indicated that the clay mixtures utilized in this study provide good geomechanical, hydraulic, and metal adsorption properties which may justify their potential use as a liner material in solid waste landfills. En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%291090-0241%282008%29134%3A8%2811 [...]

Trace elements leaching from organic soils stabilized with high carbon fly ash / Jacob J. Sauer in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 8 (Août 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 968–980 Titre : Trace elements leaching from organic soils stabilized with high carbon fly ash Type de document : texte imprimé Auteurs : Jacob J. Sauer, Auteur ; Craig H. Benson, Auteur ; Ahmet H. Aydilek, Auteur Année de publication : 2012 Article en page(s) : pp. 968–980 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Organic  soil  Fly  ash  Coal  combustion  products  CCPs  Stabilization  Trace  elements  Leaching  Sustainability Résumé : Leaching of four trace elements [cadmium (Cd), chromium (Cr), selenium (Se), and silver (Ag)] from soft organic soils stabilized with high carbon fly ashes (HCFAs) was assessed using water leach tests (WLTs) and column leach tests (CLTs) on soil alone, fly ash alone, and soil-fly ash mixtures. Concentrations from the WLTs on soil-fly ash mixtures were lower than concentrations from the WLTs on fly ash alone, and were controlled more by the fly ash than the soil. However, dilution calculations based on tests on soil alone and fly ash alone were unreliable. Thus, leaching assessments should be conducted directly on soil-fly ash mixtures. Leaching patterns from the CLTs followed first-flush and lagged-response patterns with comparable frequency, although first-flush patterns were more common with fly ash with higher calcium oxide content. Cd and Cr exhibited first-flush leaching more frequently, Ag a lagged-response pattern more frequently, and Se exhibited first-flush or lagged-response patterns with similar frequency. The hydrogen ion concentration (pH) had a strong effect on leaching concentrations, with lower concentrations of Ag and Cd and higher concentrations of Cr at a higher pH. Peak concentrations of Ag and Cd for flow-through conditions can conservatively be estimated as 50 times the WLT concentration, whereas a factor of 100 should be applied for Cr and Se for organic soil-HCFA mixtures. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000653 [article] Trace elements leaching from organic soils stabilized with high carbon fly ash [texte imprimé] / Jacob J. Sauer, Auteur ; Craig H. Benson, Auteur ; Ahmet H. Aydilek, Auteur . - 2012 . - pp. 968–980. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 8 (Août 2012) . - pp. 968–980 Mots-clés : Organic  soil  Fly  ash  Coal  combustion  products  CCPs  Stabilization  Trace  elements  Leaching  Sustainability Résumé : Leaching of four trace elements [cadmium (Cd), chromium (Cr), selenium (Se), and silver (Ag)] from soft organic soils stabilized with high carbon fly ashes (HCFAs) was assessed using water leach tests (WLTs) and column leach tests (CLTs) on soil alone, fly ash alone, and soil-fly ash mixtures. Concentrations from the WLTs on soil-fly ash mixtures were lower than concentrations from the WLTs on fly ash alone, and were controlled more by the fly ash than the soil. However, dilution calculations based on tests on soil alone and fly ash alone were unreliable. Thus, leaching assessments should be conducted directly on soil-fly ash mixtures. Leaching patterns from the CLTs followed first-flush and lagged-response patterns with comparable frequency, although first-flush patterns were more common with fly ash with higher calcium oxide content. Cd and Cr exhibited first-flush leaching more frequently, Ag a lagged-response pattern more frequently, and Se exhibited first-flush or lagged-response patterns with similar frequency. The hydrogen ion concentration (pH) had a strong effect on leaching concentrations, with lower concentrations of Ag and Cd and higher concentrations of Cr at a higher pH. Peak concentrations of Ag and Cd for flow-through conditions can conservatively be estimated as 50 times the WLT concentration, whereas a factor of 100 should be applied for Cr and Se for organic soil-HCFA mixtures. ISSN : 1090-0241 En ligne : http://ascelibrary.org/doi/abs/10.1061/%28ASCE%29GT.1943-5606.0000653