Comprehensive phase characterization of crystalline and amorphous phases of a Class F fly ash / Ryan T. Chancey in Cement and concrete research, Vol. 40 N° 1 (Janvier 2010)  

Public ISBD [article]  inCement and concrete research > Vol. 40 N° 1 (Janvier 2010) . - pp. 146-156 Titre : Comprehensive phase characterization of crystalline and amorphous phases of a Class F fly ash Type de document : texte imprimé Auteurs : Ryan T. Chancey, Auteur ; Paul Stutzman, Auteur ; Maria C.G. Juenger, Auteur Article en page(s) : pp. 146-156 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Amorphous material Characterization Image analysis Fly ash SEM X-ray powder diffraction Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : A comprehensive approach to qualitative and quantitative characterization of crystalline and amorphous constituent phases of a largely heterogeneous Class F fly ash is presented. Traditionally, fly ash composition is expressed as bulk elemental oxide content, generally determined by X-ray fluorescence spectroscopy. However, such analysis does not discern between relatively inert crystalline phases and highly reactive amorphous phases of similar elemental composition. X-ray diffraction was used to identify the crystalline phases present in the fly ash, and the Rietveld quantitative phase analysis method was applied to determine the relative proportion of each of these phases. A synergistic method of X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and multispectral image analysis was developed to identify and quantify the amorphous phases present in the fly ash. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235562%23 [...] [article] Comprehensive phase characterization of crystalline and amorphous phases of a Class F fly ash [texte imprimé] / Ryan T. Chancey, Auteur ; Paul Stutzman, Auteur ; Maria C.G. Juenger, Auteur . - pp. 146-156. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 40 N° 1 (Janvier 2010) . - pp. 146-156 Mots-clés : Amorphous material Characterization Image analysis Fly ash SEM X-ray powder diffraction Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : A comprehensive approach to qualitative and quantitative characterization of crystalline and amorphous constituent phases of a largely heterogeneous Class F fly ash is presented. Traditionally, fly ash composition is expressed as bulk elemental oxide content, generally determined by X-ray fluorescence spectroscopy. However, such analysis does not discern between relatively inert crystalline phases and highly reactive amorphous phases of similar elemental composition. X-ray diffraction was used to identify the crystalline phases present in the fly ash, and the Rietveld quantitative phase analysis method was applied to determine the relative proportion of each of these phases. A synergistic method of X-ray powder diffraction, scanning electron microscopy, energy dispersive spectroscopy, and multispectral image analysis was developed to identify and quantify the amorphous phases present in the fly ash. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=PublicationURL&_tockey=%23TOC%235562%23 [...]

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The physical and chemical characteristics of the shell of air-entrained bubbles in cement paste / M. Tyler Ley in Cement and concrete research, Vol. 39 N° 5 (Mai 2009)  

Public ISBD [article]  inCement and concrete research > Vol. 39 N° 5 (Mai 2009) . - pp. 417–425 Titre : The physical and chemical characteristics of the shell of air-entrained bubbles in cement paste Type de document : texte imprimé Auteurs : M. Tyler Ley, Auteur ; Ryan T. Chancey, Auteur ; Maria C.G. Juenger, Auteur Année de publication : 2009 Article en page(s) : pp. 417–425 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Freezing and thawing  Admixture Fresh concrete Air entrainment Résumé : Recent research has suggested that the shell of an air-entrained void is important for resisting coalescence between air-voids and diffusion of gas from the surrounding fluid. The current paper describes the physical and chemical properties of an air-void shell during the first 2 h of hydration and chemical characteristics at 60 days. Results from this research suggest that the air-void shells found in air-entrained paste have varied physical properties and the crystalline material of these shells is largely made up of fine cement particles during the first 2 h of hydration. Observations of paste at 60 days of hydration suggest that the shell is made up of calcium silicate hydrate (C–S–H) with a morphology different from that in the bulk paste. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000441 [article] The physical and chemical characteristics of the shell of air-entrained bubbles in cement paste [texte imprimé] / M. Tyler Ley, Auteur ; Ryan T. Chancey, Auteur ; Maria C.G. Juenger, Auteur . - 2009 . - pp. 417–425. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 5 (Mai 2009) . - pp. 417–425 Mots-clés : Freezing and thawing  Admixture Fresh concrete Air entrainment Résumé : Recent research has suggested that the shell of an air-entrained void is important for resisting coalescence between air-voids and diffusion of gas from the surrounding fluid. The current paper describes the physical and chemical properties of an air-void shell during the first 2 h of hydration and chemical characteristics at 60 days. Results from this research suggest that the air-void shells found in air-entrained paste have varied physical properties and the crystalline material of these shells is largely made up of fine cement particles during the first 2 h of hydration. Observations of paste at 60 days of hydration suggest that the shell is made up of calcium silicate hydrate (C–S–H) with a morphology different from that in the bulk paste. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000441

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