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Adsorption of superplasticizer admixtures on alkali-activated slag pastes / M. Palacios in Cement and concrete research, Vol. 39 N° 8 (Août 2009) 

Public ISBD [article]  in Cement and concrete research > Vol. 39 N° 8 (Août 2009) . - pp. 670–677 Titre : Adsorption of superplasticizer admixtures on alkali-activated slag pastes Type de document : texte imprimé Auteurs : M. Palacios, Auteur ; Y.F. Houst, Auteur ; P. Bowen, Auteur Année de publication : 2009 Article en page(s) : pp. 670–677 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Alkali-activated  slag  cement;  Admixtures;  Portland  cement;  Adsorption;  Rheology Résumé : Alkali-activated slag (AAS) binders are obtained by a manufacturing process less energy-intensive than ordinary Portland cement (OPC) and involves lower greenhouse gasses emission. These alkaline cements allow the production of high mechanical strength and durable concretes. In the present work, the adsorption of different superplasticizer admixtures (naphthalene-based, melamine-based and a vinyl copolymer) on the slag particles in AAS pastes using alkaline solutions with different pH values have been studied in detail. The effect of the superplasticizers on the yield stress and plastic viscosity of the AAS and OPC pastes have been also evaluated. The results obtained allowed us to conclude that the adsorption of the superplasticizers on AAS pastes is independent of the pH of the alkaline solutions used and lower than on OPC pastes. However, the effect of the admixtures on the rheological parameters depends directly on the type and dosage of the superplasticizer as well as of the binder used and, in the case of the AAS, on the pH of the alkaline activator solution. In 11.7-pH NaOH-AAS pastes the dosages of the superplasticizers required to attain similar reduction in the yield stress are ten-fold lower than for Portland cement. In this case the superplasticizers studied show a fluidizing effect considerably higher in 11.7-pH NaOH-AAS pastes than in OPC pastes. In 13.6-pH NaOH-AAS pastes, the only admixture observed to affect the rheological parameters is the naphthalene-based admixture due to its higher chemical stability in such extremely alkaline media. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001082 [article] Adsorption of superplasticizer admixtures on alkali-activated slag pastes [texte imprimé] / M. Palacios, Auteur ; Y.F. Houst, Auteur ; P. Bowen, Auteur . - 2009 . - pp. 670–677. Génie Civil Langues : Anglais (eng) in Cement and concrete research > Vol. 39 N° 8 (Août 2009) . - pp. 670–677 Mots-clés : Alkali-activated  slag  cement;  Admixtures;  Portland  cement;  Adsorption;  Rheology Résumé : Alkali-activated slag (AAS) binders are obtained by a manufacturing process less energy-intensive than ordinary Portland cement (OPC) and involves lower greenhouse gasses emission. These alkaline cements allow the production of high mechanical strength and durable concretes. In the present work, the adsorption of different superplasticizer admixtures (naphthalene-based, melamine-based and a vinyl copolymer) on the slag particles in AAS pastes using alkaline solutions with different pH values have been studied in detail. The effect of the superplasticizers on the yield stress and plastic viscosity of the AAS and OPC pastes have been also evaluated. The results obtained allowed us to conclude that the adsorption of the superplasticizers on AAS pastes is independent of the pH of the alkaline solutions used and lower than on OPC pastes. However, the effect of the admixtures on the rheological parameters depends directly on the type and dosage of the superplasticizer as well as of the binder used and, in the case of the AAS, on the pH of the alkaline activator solution. In 11.7-pH NaOH-AAS pastes the dosages of the superplasticizers required to attain similar reduction in the yield stress are ten-fold lower than for Portland cement. In this case the superplasticizers studied show a fluidizing effect considerably higher in 11.7-pH NaOH-AAS pastes than in OPC pastes. In 13.6-pH NaOH-AAS pastes, the only admixture observed to affect the rheological parameters is the naphthalene-based admixture due to its higher chemical stability in such extremely alkaline media. ISSN : 0008-8846 En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609001082