Abstract
Coatings can contribute to extending service life of concrete structures exposed to marine environents by reducing the rate of chloride penetration. In the present paper, the effect of coatings on the rate of chloride uptake was studied by measuring their concentration profiles at different, times, extending up to 24 months. Using a solution of the so-called Fick’s second law of diffusion, least-square fitting leads to the value of chloride concentration under the coating (C o ) which allowed us to compare the effectiveness of different coatings. Dependeng on the formulation, some of the studied acrylic coatings could reduce the value ofC o by more than 80% in comparison to the unpainted concrete. Water permeability coefficients were measured for the same coatings, according to EN 1062-3. The ranking of effectiveness to stop chlorides is the same as the water imperviousness, but the minimum requrement proposed by prEN 1504-2 (0.1 kg.m−2h−0.5) did not prove to be enough for an efficient protection against chloride permeation.
Résumé
Les revêtements peuvent contribuer à l’extension de la durée de vie des structures en béton exposées à des environments marins en réduisant le taux de pénétration des chlorures. Dans cet article, l’effet des revêtements sur le taux de pénétration des chlorures dans le béton a été suivi en mesurant leurs profils de concentration à des périodes différentes jusqu’à 24 mois d’exposition. En utilisant une solution de la seconde Loi de Fick, nous avons appliqué la méthode des moindres carrés au taux de concentration en ions chlorures sous le revêtement (Co), afin de comparer l’efficacité de plusieurs revêtements. Selon la formulation, quelques peintures acryliques qui ont été étudiées ont pu réduire la valeur de Co de plus de 80% en comparaison avec le béton sans revêtement. Les coefficients de perméabilité à l’eau des mêmes revêtements ont été obtenus d’après la norme européene EN 1062-3. Le classement des revêtements par degré d’efficacité contre l’entrée des chlorues est le même que pour leur imperméabilité à l’eau, mais la quantié minimale mentionnée dans le projet de norme européenne EN 1504-2 (0,1 kg.m−2.h−0,5) n’est pas suffisante pour que le revêtement protège de façon efficace le béton contre la pénétration des chlorures.
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Editorial Note The National Laboratory of Civil Engineering (LNEC, Portugal) is a RILEM Titular Member.
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Rodrigues, M.P.M.C., Costa, M.R.N., Mendes, A.M. et al. Effectiveness of surface coatings to protect reinforced concrete in marine environments. Mat. Struct. 33, 618–626 (2000). https://doi.org/10.1007/BF02480601
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DOI: https://doi.org/10.1007/BF02480601