Abstract
The paper presents the results of a corrosion investigation on rebar electrodes embedded in concrete prism specimens which were exposed to cycles of sea-water spray for up to about 600 days (1200 marine cycles). The w/c ratio of the matrix was varied between 0.45 and 0.76 and the cement content ranged between 330 and 530 kg m−3. Corrosion potential and polarization resistance of the electrodes were monitored at regular intervals by means of electrochemical procedures using a potentiostat apparatus. The Cl− and OH− concentrations in the matrix were also determined at the level of rebar electrodes. The results show that cement content has an insignificant influence on rebar corrosion, w/c ratio being the dominant factor which controls corrosion. The Cl− and OH− concentrations of the pore fluid are of secondary importance relative to w/c ratio. Acceptable corrosion rates are achieved at a w/c of 0.45, with the pore fluid Cl−/OH− ratio reaching a value of 11.
Resume
Cet article présente les résultats d’une étude sur la corrosion de barres de renforcement formées par des armatures enrobées dans des prismes de béton exposés à l’eau de mer pendant des cycles allant jusqu’ à 600 jours (1200 cycles marins). On a fait varier le rapport eau/ciment de la matrice de 0,45 à 0,76 et la teneur en ciment de 300 à 530 kg m−3. On a contrôlé le potentiel de corrosion et la résistance à la polarisation des électrodes à intervalles réguliers par des méthodes électro-chimiques. On a également déterminé les concentrations en Cl− et OH− au niveau des électrodes.
Les résultats montrent que la teneur en ciment a un effet insignifiant sur la corrosion du renforcement, le rapport eau/ciment étant le facteur dominant qui régit la corrosion. L’influence des concentrations en Cl− et OH− du liquide interstitiel est relativement secondaire. On atteint des taux de corrosion acceptables avec un rapport eau/ciment de 0,45 et un rapport Cl−/OH− du liquide interstitiel de 11.
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Mangat, P.S., Molloy, B.T. Factors influencing chloride-induced corrosion of reinforcement in concrete. Materials and Structures 25, 404–411 (1992). https://doi.org/10.1007/BF02472256
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DOI: https://doi.org/10.1007/BF02472256