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Effect of alkalis on fresh C–S–H gels. FTIR analysis / I. García Lodeiro in Cement and concrete research, Vol. 39 N° 3 (Mars 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 3 (Mars 2009) . - pp. 147–153 Titre : Effect of alkalis on fresh C–S–H gels. FTIR analysis Type de document : texte imprimé Auteurs : I. García Lodeiro, Auteur ; D.E. Macphee, Auteur ; A. Palomo, Auteur Année de publication : 2009 Article en page(s) : pp. 147–153 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Calcium–Silicate–Hydrate  (C–S–H);  Spectroscopy;  Alkalis Résumé : The present study addresses the effect of different concentrations of Na2O on the structure of a composition of fresh C–S–H gels. The gels were synthesized from laboratory reagents, using calcium nitrate as the source of calcium and a sodium silicate solution for the silicon. A 10-M solution of NaOH was used to maintain a pH of over 13 throughout. The synthesized gels were exposed to different amounts of 8-M NaOH to determine their chemical stability and subsequently characterized with Fourier transform IR spectroscopy. The results showed that the addition of different concentrations of sodium leads to C–S–H gel modification even in the very short term. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000039 [article] Effect of alkalis on fresh C–S–H gels. FTIR analysis [texte imprimé] / I. García Lodeiro, Auteur ; D.E. Macphee, Auteur ; A. Palomo, Auteur . - 2009 . - pp. 147–153. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 3 (Mars 2009) . - pp. 147–153 Mots-clés : Calcium–Silicate–Hydrate  (C–S–H);  Spectroscopy;  Alkalis Résumé : The present study addresses the effect of different concentrations of Na2O on the structure of a composition of fresh C–S–H gels. The gels were synthesized from laboratory reagents, using calcium nitrate as the source of calcium and a sodium silicate solution for the silicon. A 10-M solution of NaOH was used to maintain a pH of over 13 throughout. The synthesized gels were exposed to different amounts of 8-M NaOH to determine their chemical stability and subsequently characterized with Fourier transform IR spectroscopy. The results showed that the addition of different concentrations of sodium leads to C–S–H gel modification even in the very short term. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609000039

Effect on fresh C-S-H gels of the simultaneous addition of alkali and aluminium / I. García Lodeiro in Cement and concrete research, Vol. 40 N° 1 (Janvier 2010) 

Public ISBD [article]  in Cement and concrete research > Vol. 40 N° 1 (Janvier 2010) . - pp. 27-32 Titre : Effect on fresh C-S-H gels of the simultaneous addition of alkali and aluminium Type de document : texte imprimé Auteurs : I. García Lodeiro, Auteur ; A. Fernandez-Jimenez, Auteur ; A. Palomo, Auteur Article en page(s) : pp. 27-32 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Calcium-Silicate-Hydrate  (C-S-H)  Spectroscopy  TEM  Stratlingite Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Reducing Portland cement content in cementitious binders offers a means to address the adverse environmental impacts of Portland cement manufacture. This paper investigates the impacts on hydration product chemistry of partially replacing Portland cement with alkali-activated aluminosilicates. Here, short-term effects of soluble alkali and aluminium, likely to be available in an alkali-activated system, on the structure of synthetic C-S-H gels are assessed. .C-S-H gels (synthesized at pH values of over 13) were mixed with different concentrations of aluminium nitrate and sodium hydroxide. The gels were characterized by FTIR, TEM/EDX and XRD 72 h later. The results showed that both alkali and aluminium increased the degree of silicate polymerisation in the C-S-H gels and precipitated a crystalline calcium aluminosilicate phase. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TWG-4X5YWSN-2&_user=6 [...] [article] Effect on fresh C-S-H gels of the simultaneous addition of alkali and aluminium [texte imprimé] / I. García Lodeiro, Auteur ; A. Fernandez-Jimenez, Auteur ; A. Palomo, Auteur . - pp. 27-32. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 40 N° 1 (Janvier 2010) . - pp. 27-32 Mots-clés : Calcium-Silicate-Hydrate  (C-S-H)  Spectroscopy  TEM  Stratlingite Index. décimale : 691 Matériaux de construction. Pièces et parties composantes Résumé : Reducing Portland cement content in cementitious binders offers a means to address the adverse environmental impacts of Portland cement manufacture. This paper investigates the impacts on hydration product chemistry of partially replacing Portland cement with alkali-activated aluminosilicates. Here, short-term effects of soluble alkali and aluminium, likely to be available in an alkali-activated system, on the structure of synthetic C-S-H gels are assessed. .C-S-H gels (synthesized at pH values of over 13) were mixed with different concentrations of aluminium nitrate and sodium hydroxide. The gels were characterized by FTIR, TEM/EDX and XRD 72 h later. The results showed that both alkali and aluminium increased the degree of silicate polymerisation in the C-S-H gels and precipitated a crystalline calcium aluminosilicate phase. DEWEY : 620.13 ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TWG-4X5YWSN-2&_user=6 [...]