Abstract
This paper deals with the effect of the leaching process of cement-based materials on their mechanical properties. This process mainly induces a total leaching of Ca(OH)2 and a progressive decalcification of the C-S-H leading in turn to a gradient of C/S ratio in the leaching zone. Modeling of the deterioration of cement paste exposed to leaching consists of a decrease in the local elastic modulus with both a damage function d and an aging function L:E=E0 (1-d)(1-L).
The main parameter fo the aging function is the residual calcium content in the material. This calcium content depends directly on the thickness of the degraded zone and on the different types of hydrates in the cement paste.
The non-linearity of the mechanical behavior of the cement-based material is described by a damage function whose main state parameter is the equivalent strain. The characteristic parameters of the material are identified by a compressive loading test.
The model of aging damage behavior proposed in this paper corresponds perfectly with the experimental results obtained in the case of a uniaxial compressive load.
Résumé
Cet article traite de l’influence de la lixiviation des matériaux à base cimentaire sur leurs propriétés mécaniques. Cette attaque chimique provoque essentiellement une dissolution totale de la Portlandite et une décalcification progressive des C-S-H caractérisée par un gradient constant du rapport C/S dans la zone lixiviée. La modélisation de la dégradation de la pâte de ciment subissant une lixiviation est obtenue en diminuant le module élastique local par l’intermédiaire d’une fonction d’endommagement d et d’une fonction de vieillissement L:E=E0 (1-d)(1-L).
La variable d’état de la fonction de vieillissement est le taux de calcium résiduel en phase solide. Ce taux de calcium est directement fonction de l’épaisseur lixiviée et des hydrates composant le liant cimentaire.
La non-linéarité du comportement mécanique du liant cimentaire est décrit par une fonction d’endommagement dont la variable d’état est la déformation équivalente. Les paramètres caractéristiques du matériau sont identifiés à partir d’un essai de compression simple.
Le modèle de comportement élastique endommageable vieillissant proposé, qui est exploité pour cet article dans le cas d’une sollicitation de compression simple, fait apparaître une excellente concordance avec les résultats expérimentaux.
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Carde, C., François, R. Aging damage model of concrete behavior during the leaching process. Mat. Struct. 30, 465–472 (1997). https://doi.org/10.1007/BF02524774
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DOI: https://doi.org/10.1007/BF02524774