Documents disponibles écrits par cet auteur

Assessment of sulfate-induced swell in stabilized dredged material / Maria Chrysochoou in Journal of geotechnical and geoenvironmental engineering, Vol. 138 N° 3 (Mars 2012) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 3 (Mars 2012) . - pp. 407-414 Titre : Assessment of sulfate-induced swell in stabilized dredged material : Is ettringite always a problem? Type de document : texte imprimé Auteurs : Maria Chrysochoou, Auteur ; Dennis G. Grubb, Auteur ; Nicholas E. Malasavage, Auteur Année de publication : 2012 Article en page(s) : pp. 407-414 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Swelling  Sulfate  Dredge  spoil  Cement  Lime  Cement  kiln  dust  Soil  mixing Résumé : This paper is the last in a series related to pozzolanically stabilizing dredged material (DM) using up to 20 different combinations of lime, cement kiln dust (CKD), fly ash (FA), Portland cement (PC), and slag cement. The fine-grained nature of the DM and the presence of high sulfate concentrations (0.6–3.25% by weight) in the stabilized dredged material (SDM) blends derived from the raw materials themselves posed concern for potential ettringite formation and swell. The sulfate contents of the SDM blends were well in excess of the National Lime Association’s thresholds for mitigating against swell (<0.8% by weight SO4). The quantitative mineralogical results showed that the lime and lime/FA SDM blends showed moderate to high ettringite formation (1.6–4.6% by weight) up to 6 months of curing, with all available sulfate bound to ettringite. The lime and lime/FA SDM blends consistently maintained the highest pHs through 6 months, which caused continued release of alumina and increases in strength. The CKD and CKD/FA SDM blends showed the highest ettringite contents through 28 days of curing (up to 5%), but with little additional formation of ettringite through 6 months of curing. The total sulfate content of the SDM blends was not a good predictor of ettringite formation potential, because of decreases in pH below the ettringite stability threshold and, even more importantly, the apparent limited availability of soluble alumina in the SDM blends. Swell tests performed on six SDM blends showed slight consolidation, and no ettringite was detected in the two specimens that swelled. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v138/i3/p407_s1?isAuthorized=no [article] Assessment of sulfate-induced swell in stabilized dredged material : Is ettringite always a problem? [texte imprimé] / Maria Chrysochoou, Auteur ; Dennis G. Grubb, Auteur ; Nicholas E. Malasavage, Auteur . - 2012 . - pp. 407-414. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 138 N° 3 (Mars 2012) . - pp. 407-414 Mots-clés : Swelling  Sulfate  Dredge  spoil  Cement  Lime  Cement  kiln  dust  Soil  mixing Résumé : This paper is the last in a series related to pozzolanically stabilizing dredged material (DM) using up to 20 different combinations of lime, cement kiln dust (CKD), fly ash (FA), Portland cement (PC), and slag cement. The fine-grained nature of the DM and the presence of high sulfate concentrations (0.6–3.25% by weight) in the stabilized dredged material (SDM) blends derived from the raw materials themselves posed concern for potential ettringite formation and swell. The sulfate contents of the SDM blends were well in excess of the National Lime Association’s thresholds for mitigating against swell (<0.8% by weight SO4). The quantitative mineralogical results showed that the lime and lime/FA SDM blends showed moderate to high ettringite formation (1.6–4.6% by weight) up to 6 months of curing, with all available sulfate bound to ettringite. The lime and lime/FA SDM blends consistently maintained the highest pHs through 6 months, which caused continued release of alumina and increases in strength. The CKD and CKD/FA SDM blends showed the highest ettringite contents through 28 days of curing (up to 5%), but with little additional formation of ettringite through 6 months of curing. The total sulfate content of the SDM blends was not a good predictor of ettringite formation potential, because of decreases in pH below the ettringite stability threshold and, even more importantly, the apparent limited availability of soluble alumina in the SDM blends. Swell tests performed on six SDM blends showed slight consolidation, and no ettringite was detected in the two specimens that swelled. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v138/i3/p407_s1?isAuthorized=no

Importance of mineralogy in the geoenvironmental characterization and treatment of chromite ore processing residue / Maria Chrysochoou in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 3 (Mars 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 3 (Mars 2010) . - pp. 510-521 Titre : Importance of mineralogy in the geoenvironmental characterization and treatment of chromite ore processing residue Type de document : texte imprimé Auteurs : Maria Chrysochoou, Auteur ; Dimitris Dermatas, Auteur ; Dennis G. Grubb, Auteur Article en page(s) : pp. 510-521 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Chromium  Mineralogy  Site  investigation  Expansive  soils  Hazardous  wastes Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The geoenvironmental characterization of COPR at two deposition sites (New Jersey and Maryland) included geotechnical, chemical, mineralogical, and leaching analyses of three main chromite ore processing residue (COPR) types [gray-black (GB), hard brown (HB), clayey (C)]. Quantitative mineralogical analyses were instrumental in the delineation of the geochemical differences between the three COPR types, which enabled a framework to predict COPR response to potential remediation schemes. Overall, COPR mineralogy resembled cement, with hydration and pozzolanic reactions dominating its geochemistry. GB COPR was largely unreacted despite its prolonged exposure to humid conditions, while HB COPR was completely hydrated and contained high Cr(VI) concentrations. The two materials were chemically similar, with dilution accounting for the chemical and density differences. While the total acid neutralization capacity (ANC) of GB and HB was the same, the ANC at high pH (8–12) was higher in HB due to the dominance of hydrating materials, leading to more buffering capacity and lower Cr(VI) leaching levels. It is concluded that GB and HB were derived from the same ore and process and that postdepositional transformations account for the emergence of HB layers in COPR sites. The physicochemical properties of HB [hardness, high and inaccessible Cr(VI), high ANC] are complicating factors for in situ COPR reductive treatment in the presence of HB. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...] [article] Importance of mineralogy in the geoenvironmental characterization and treatment of chromite ore processing residue [texte imprimé] / Maria Chrysochoou, Auteur ; Dimitris Dermatas, Auteur ; Dennis G. Grubb, Auteur . - pp. 510-521. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 3 (Mars 2010) . - pp. 510-521 Mots-clés : Chromium  Mineralogy  Site  investigation  Expansive  soils  Hazardous  wastes Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The geoenvironmental characterization of COPR at two deposition sites (New Jersey and Maryland) included geotechnical, chemical, mineralogical, and leaching analyses of three main chromite ore processing residue (COPR) types [gray-black (GB), hard brown (HB), clayey (C)]. Quantitative mineralogical analyses were instrumental in the delineation of the geochemical differences between the three COPR types, which enabled a framework to predict COPR response to potential remediation schemes. Overall, COPR mineralogy resembled cement, with hydration and pozzolanic reactions dominating its geochemistry. GB COPR was largely unreacted despite its prolonged exposure to humid conditions, while HB COPR was completely hydrated and contained high Cr(VI) concentrations. The two materials were chemically similar, with dilution accounting for the chemical and density differences. While the total acid neutralization capacity (ANC) of GB and HB was the same, the ANC at high pH (8–12) was higher in HB due to the dominance of hydrating materials, leading to more buffering capacity and lower Cr(VI) leaching levels. It is concluded that GB and HB were derived from the same ore and process and that postdepositional transformations account for the emergence of HB layers in COPR sites. The physicochemical properties of HB [hardness, high and inaccessible Cr(VI), high ANC] are complicating factors for in situ COPR reductive treatment in the presence of HB. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JGGEFK&smode=strres [...]

Stabilized dredged material. I, Parametric Study / Dennis G. Grubb in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 8 (Août 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1011-1024 Titre : Stabilized dredged material. I, Parametric Study Type de document : texte imprimé Auteurs : Dennis G. Grubb, Auteur ; Maria Chrysochoou, Auteur ; Charles J. Smith, Auteur Année de publication : 2010 Article en page(s) : pp. 1011-1024 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Soil  stabilization  Soil  cement  Dredge  spoil  By-Product  utilization  Laboratory  tests  Physical  properties Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This study presents the results of a treatability study for dredged material (DM) stabilization using 20 combinations of pozzolanic agents (lime, cement kiln dust, high alkali and slag cements, and fly ash). The DM consisted of CH/OH soil excavated from the U.S. Army Corps of Engineers Craney Island confined disposal facility in Hampton Roads, Virginia, having an in situ moisture content of approximately 130% and void ratio of 3.35. Mix designs were prepared for each stabilized DM (SDM) blend using a 3-day mellowing period for the SDM blends to become compactable. Typical maximum dry unit weights were on the order of 11.9–12.9 kN/m3 (76–82 lb/ft3), for total dry pozzolan doses to wet DM between 5 and 95%, the upper dosing limit being unconstrained for potential use of the SDM blends as fill. Unconfined compression strength (UCS) testing of the SDM blends using DM with an initial MC of 132.5% was completed in accordance with ASTM D1632 and ASTM D1633 for curing times of 7, 28, and 180 days. The 28-day cured specimens had UCS values up to 800 kPa (115 psi). Leaching analyses of the various SDM blends for Resource Conservation and Recovery Act metals using toxicity characteristic leaching procedure and deionized water solutions for extended durations and contact times illustrated that the SDM blends were nonhazardous and virtually identical to the raw DM. Overall, the use of industrial by-products in SDM blends suggests that it may be possible to undertake large-scale fill construction that is sustainable, cost-effective, and environmentally protective of human health and the environment. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1011_s1?isAuthorized=no [article] Stabilized dredged material. I, Parametric Study [texte imprimé] / Dennis G. Grubb, Auteur ; Maria Chrysochoou, Auteur ; Charles J. Smith, Auteur . - 2010 . - pp. 1011-1024. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1011-1024 Mots-clés : Soil  stabilization  Soil  cement  Dredge  spoil  By-Product  utilization  Laboratory  tests  Physical  properties Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : This study presents the results of a treatability study for dredged material (DM) stabilization using 20 combinations of pozzolanic agents (lime, cement kiln dust, high alkali and slag cements, and fly ash). The DM consisted of CH/OH soil excavated from the U.S. Army Corps of Engineers Craney Island confined disposal facility in Hampton Roads, Virginia, having an in situ moisture content of approximately 130% and void ratio of 3.35. Mix designs were prepared for each stabilized DM (SDM) blend using a 3-day mellowing period for the SDM blends to become compactable. Typical maximum dry unit weights were on the order of 11.9–12.9 kN/m3 (76–82 lb/ft3), for total dry pozzolan doses to wet DM between 5 and 95%, the upper dosing limit being unconstrained for potential use of the SDM blends as fill. Unconfined compression strength (UCS) testing of the SDM blends using DM with an initial MC of 132.5% was completed in accordance with ASTM D1632 and ASTM D1633 for curing times of 7, 28, and 180 days. The 28-day cured specimens had UCS values up to 800 kPa (115 psi). Leaching analyses of the various SDM blends for Resource Conservation and Recovery Act metals using toxicity characteristic leaching procedure and deionized water solutions for extended durations and contact times illustrated that the SDM blends were nonhazardous and virtually identical to the raw DM. Overall, the use of industrial by-products in SDM blends suggests that it may be possible to undertake large-scale fill construction that is sustainable, cost-effective, and environmentally protective of human health and the environment. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1011_s1?isAuthorized=no

Stabilized dredged material. III, Mineralogical perspective / Maria Chrysochoou in Journal of geotechnical and geoenvironmental engineering, Vol. 136 N° 8 (Août 2010) 

Public ISBD [article]  in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1037-1050 Titre : Stabilized dredged material. III, Mineralogical perspective Type de document : texte imprimé Auteurs : Maria Chrysochoou, Auteur ; Dennis G. Grubb, Auteur ; Kelly L. Drengler, Auteur Année de publication : 2010 Article en page(s) : pp. 1037-1050 Note générale : Géotechnique Langues : Anglais (eng) Mots-clés : Mineralogy  Soil  stabilization  Soil  cement  Dredge  spoil  Byproduct  utilization  Laboratory  tests Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The prior two papers in this series reported on the geoenvironmental and geomechanical properties of 20 stabilized dredged material (SDM) blends using dredged material (DM) from the U.S. Army Corps of Engineers Craney Island confined disposal facility. The pozzolans included lime, cement kiln dust (CKD), class F fly ash, and two cements (portland and slag cement). This paper reports on the mineralogical evolution of the SDM blends over a 6-month curing period using techniques new to mainstream geotechnical engineering: X-ray diffraction (XRD) with Rietveld quantification analysis which allows direct quantitative mineralogical comparisons between soil samples. Despite being classified as a high plasticity clay-organic clay (CH/OH soil), XRD showed that the DM contained no montmorillonite, illite or kaolinite, and was thus mineralogically unreactive. The quartz, feldspar, and mica contents were numerically tracked and were shown to remain stable 6 months after blending. The chlorite (in DM) content decreased over time and with the fly ash served as the sources of soluble silica and alumina for pozzolanic reactions especially in the lime-based SDM blends. Lime in the lime-based blends persisted in significant quantities (3%) as unreacted portlandite [Ca(OH)2] even at 6 months curing, indicating that the solubility of silica in the DM was the limiting factor for strength development. New (ettringite and hydrocalumite) mineral formation was quantified. CKD provided high early strength (7 and 28 days) when used in combination with small amounts of lime that provided prolonged pH buffering; CKD alone or in combination with fly ash did not maintain elevated pH (>10.8) over 6 months. Overall, the unconfined compressive strength, pH, and mineralogy results at 6 months were substantially different compared to the standard curing time of 28 days, confirming similar findings of previous long-term stabilization-solidification studies. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1037_s1?isAuthorized=no [article] Stabilized dredged material. III, Mineralogical perspective [texte imprimé] / Maria Chrysochoou, Auteur ; Dennis G. Grubb, Auteur ; Kelly L. Drengler, Auteur . - 2010 . - pp. 1037-1050. Géotechnique Langues : Anglais (eng) in Journal of geotechnical and geoenvironmental engineering > Vol. 136 N° 8 (Août 2010) . - pp. 1037-1050 Mots-clés : Mineralogy  Soil  stabilization  Soil  cement  Dredge  spoil  Byproduct  utilization  Laboratory  tests Index. décimale : 624.1 Infrastructures.Ouvrages en terre. Fondations. Tunnels Résumé : The prior two papers in this series reported on the geoenvironmental and geomechanical properties of 20 stabilized dredged material (SDM) blends using dredged material (DM) from the U.S. Army Corps of Engineers Craney Island confined disposal facility. The pozzolans included lime, cement kiln dust (CKD), class F fly ash, and two cements (portland and slag cement). This paper reports on the mineralogical evolution of the SDM blends over a 6-month curing period using techniques new to mainstream geotechnical engineering: X-ray diffraction (XRD) with Rietveld quantification analysis which allows direct quantitative mineralogical comparisons between soil samples. Despite being classified as a high plasticity clay-organic clay (CH/OH soil), XRD showed that the DM contained no montmorillonite, illite or kaolinite, and was thus mineralogically unreactive. The quartz, feldspar, and mica contents were numerically tracked and were shown to remain stable 6 months after blending. The chlorite (in DM) content decreased over time and with the fly ash served as the sources of soluble silica and alumina for pozzolanic reactions especially in the lime-based SDM blends. Lime in the lime-based blends persisted in significant quantities (3%) as unreacted portlandite [Ca(OH)2] even at 6 months curing, indicating that the solubility of silica in the DM was the limiting factor for strength development. New (ettringite and hydrocalumite) mineral formation was quantified. CKD provided high early strength (7 and 28 days) when used in combination with small amounts of lime that provided prolonged pH buffering; CKD alone or in combination with fly ash did not maintain elevated pH (>10.8) over 6 months. Overall, the unconfined compressive strength, pH, and mineralogy results at 6 months were substantially different compared to the standard curing time of 28 days, confirming similar findings of previous long-term stabilization-solidification studies. DEWEY : 624.1 ISSN : 1090-0241 En ligne : http://ascelibrary.org/gto/resource/1/jggefk/v136/i8/p1037_s1?isAuthorized=no