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Effects of early-age thermal behaviour on damage risks in massive concrete structures / Matthieu Briffaut in European journal of environmental and civil engineering, Vol. 16 N° 5 (Mai 2012) 

Public ISBD [article]  in European journal of environmental and civil engineering > Vol. 16 N° 5 (Mai 2012) . - pp. 589-605 Titre : Effects of early-age thermal behaviour on damage risks in massive concrete structures Type de document : texte imprimé Auteurs : Matthieu Briffaut, Auteur ; Benboudjema, Farid, Auteur ; Torrenti, Jean-Michel, Auteur Année de publication : 2012 Article en page(s) : pp. 589-605 Note générale : Génie Civil Langues : Français (fre) Mots-clés : Early  age  Thermal  properties  Concrete  Massive  structures Résumé : At early age, temperature in massive concrete structures may reach over 70°C because hydration is an exothermic chemical reaction. Temperature evolution (increasing followed by decreasing temperature) can lead to damage risks in the short and long term. Firstly, cracking due to self-restrained strains (essentially thermal strains) can occur (which increase the transport properties and so the kinetics of degradation); and secondly, delayed ettringite formation can appear. In addition, if autogenous and thermal strains are restrained, compressive stresses and then tensile stresses increase, which can cause crossing cracks. However, this paper will not deal with these phenomena. In the first part, sensitivity to delayed ettringite formation and early age cracks by self-restrained strains are studied with regards to the environmental conditions by a numerical approach. This part shows that the external temperature has a significant impact on the maximal temperature reached, but that the temperature difference between the core and the surface is mainly impacted by the wind velocity. Then, a parametric study on the effect of the variation of thermal properties at early age has been achieved and shows that it needs to be taken into account. Finally, visco-elastic mechanical calculations show the impact of thermal property variation on the stresses generated by self restraint. DEWEY : 624 ISSN : 1964-8189 En ligne : http://www.tandfonline.com/doi/abs/10.1080/19648189.2012.668016 [article] Effects of early-age thermal behaviour on damage risks in massive concrete structures [texte imprimé] / Matthieu Briffaut, Auteur ; Benboudjema, Farid, Auteur ; Torrenti, Jean-Michel, Auteur . - 2012 . - pp. 589-605. Génie Civil Langues : Français (fre) in European journal of environmental and civil engineering > Vol. 16 N° 5 (Mai 2012) . - pp. 589-605 Mots-clés : Early  age  Thermal  properties  Concrete  Massive  structures Résumé : At early age, temperature in massive concrete structures may reach over 70°C because hydration is an exothermic chemical reaction. Temperature evolution (increasing followed by decreasing temperature) can lead to damage risks in the short and long term. Firstly, cracking due to self-restrained strains (essentially thermal strains) can occur (which increase the transport properties and so the kinetics of degradation); and secondly, delayed ettringite formation can appear. In addition, if autogenous and thermal strains are restrained, compressive stresses and then tensile stresses increase, which can cause crossing cracks. However, this paper will not deal with these phenomena. In the first part, sensitivity to delayed ettringite formation and early age cracks by self-restrained strains are studied with regards to the environmental conditions by a numerical approach. This part shows that the external temperature has a significant impact on the maximal temperature reached, but that the temperature difference between the core and the surface is mainly impacted by the wind velocity. Then, a parametric study on the effect of the variation of thermal properties at early age has been achieved and shows that it needs to be taken into account. Finally, visco-elastic mechanical calculations show the impact of thermal property variation on the stresses generated by self restraint. DEWEY : 624 ISSN : 1964-8189 En ligne : http://www.tandfonline.com/doi/abs/10.1080/19648189.2012.668016