ASR pessimum behaviour of siliceous limestone aggregates / E. Garcia-Diaz in Cement and concrete research, Vol. 40 N° 4 (Avril 2010)  

Public ISBD [article]  inCement and concrete research > Vol. 40 N° 4 (Avril 2010) . - pp. 546–549 Titre : ASR pessimum behaviour of siliceous limestone aggregates Type de document : texte imprimé Auteurs : E. Garcia-Diaz, Auteur Année de publication : 2012 Article en page(s) : pp. 546–549 Note générale : Bibliogr. Langues : Anglais (eng) Mots-clés : Aggregate  Alkali-Aggregate Reaction ,Calcium Silicate Hydrate (C-S-H) Concrete Pessimum effect Résumé : Siliceous limestone aggregates have “pessimum” behaviours similar to those observed for pure siliceous aggregates such as flint or opal. For high alkali contents concretes based on fine and coarse reactive siliceous limestone aggregates swell less than concretes based on fine reactive siliceous limestone aggregates and non-reactive coarse aggregates. The reduction of the swelling is more significant for a “micritic” limestone containing highly reactive free silica than for a “sparitic” limestone containing less reactive free silica. The consumption of a part of the alkalis by non-expansive processes such as chemical sorption on silanol sites of reactive silica and pozzolanic C–S–H is expected to explain the reduction of the swelling. En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609002221 [article] ASR pessimum behaviour of siliceous limestone aggregates [texte imprimé] / E. Garcia-Diaz, Auteur . - 2012 . - pp. 546–549. Bibliogr. Langues : Anglais (eng) in Cement and concrete research > Vol. 40 N° 4 (Avril 2010) . - pp. 546–549 Mots-clés : Aggregate  Alkali-Aggregate Reaction ,Calcium Silicate Hydrate (C-S-H) Concrete Pessimum effect Résumé : Siliceous limestone aggregates have “pessimum” behaviours similar to those observed for pure siliceous aggregates such as flint or opal. For high alkali contents concretes based on fine and coarse reactive siliceous limestone aggregates swell less than concretes based on fine reactive siliceous limestone aggregates and non-reactive coarse aggregates. The reduction of the swelling is more significant for a “micritic” limestone containing highly reactive free silica than for a “sparitic” limestone containing less reactive free silica. The consumption of a part of the alkalis by non-expansive processes such as chemical sorption on silanol sites of reactive silica and pozzolanic C–S–H is expected to explain the reduction of the swelling. En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609002221

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Influence of lithium hydroxide on alkali–silica reaction / D. Bulteel in Cement and concrete research, Vol. 40 N° 4 (Avril 2010)  

Public ISBD [article]  inCement and concrete research > Vol. 40 N° 4 (Avril 2010) . - pp. 526–530 Titre : Influence of lithium hydroxide on alkali–silica reaction Type de document : texte imprimé Auteurs : D. Bulteel, Auteur ; E. Garcia-Diaz, Auteur ; P. Dégrugilliers, Auteur Année de publication : 2012 Article en page(s) : pp. 526–530 Note générale : Bibliogr. Langues : Anglais (eng) Mots-clés : Alkali-silica reaction  Reactive aggregate Reaction degree Lithium Inhibitor Résumé : Several papers show that the use of lithium limits the development of alkali–silica reaction (ASR) in concrete. The aim of this study is to improve the understanding of lithium's role on the alteration mechanism of ASR. The approach used is a chemical method which allowed a quantitative measurement of the specific degree of reaction of ASR. The chemical concrete sub-system used, called model reactor, is composed of the main ASR reagents: reactive aggregate, portlandite and alkaline solution. Different reaction degrees are measured and compared for different alkaline solutions: NaOH, KOH and LiOH. Alteration by ASR is observed with the same reaction degrees in the presence of NaOH and KOH, accompanied by the consumption of hydroxyl concentration. On the other hand with LiOH, ASR is very limited. Reaction degree values evolve little and the hydroxyl concentration remains about stable. These observations demonstrate that lithium ions have an inhibitor role on ASR. En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609002233 [article] Influence of lithium hydroxide on alkali–silica reaction [texte imprimé] / D. Bulteel, Auteur ; E. Garcia-Diaz, Auteur ; P. Dégrugilliers, Auteur . - 2012 . - pp. 526–530. Bibliogr. Langues : Anglais (eng) in Cement and concrete research > Vol. 40 N° 4 (Avril 2010) . - pp. 526–530 Mots-clés : Alkali-silica reaction  Reactive aggregate Reaction degree Lithium Inhibitor Résumé : Several papers show that the use of lithium limits the development of alkali–silica reaction (ASR) in concrete. The aim of this study is to improve the understanding of lithium's role on the alteration mechanism of ASR. The approach used is a chemical method which allowed a quantitative measurement of the specific degree of reaction of ASR. The chemical concrete sub-system used, called model reactor, is composed of the main ASR reagents: reactive aggregate, portlandite and alkaline solution. Different reaction degrees are measured and compared for different alkaline solutions: NaOH, KOH and LiOH. Alteration by ASR is observed with the same reaction degrees in the presence of NaOH and KOH, accompanied by the consumption of hydroxyl concentration. On the other hand with LiOH, ASR is very limited. Reaction degree values evolve little and the hydroxyl concentration remains about stable. These observations demonstrate that lithium ions have an inhibitor role on ASR. En ligne : http://www.sciencedirect.com/science/article/pii/S0008884609002233

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