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Rebolledo N.,Center for Safety and Durability of Structures and Materials | Andrade C.,Affiliation or Safety and Durability of Structures and Materials
RILEM Bookseries | Year: 2012

In marine environments, reinforcement corrosion develops due to the penetration of chlorides through the concrete pores. Initially the corrosion appears as localized attack, but when the chlorides arrive in high quantities, it extends to the bar surfaces which corrode entirely. In numerous previous studies, the detection of corrosion and its evolution have been monitored by means of measuring and presenting the variation of corrosion rate over time. This representation can be used to deduce when corrosion initiates on a steel bar and how it evolves with time. However, as the corrosion rate changes with temperature and the corrosion process itself evolves, this representation may not be clear enough to be used for comparative purposes. The present work proposes a parallel use of accumulated corrosion depth, which is obtained by the integration of each age of the corrosion rate-time curve. This kind of representation enables the determination of corrosion depth at each age and appears more appropriate for comparative purposes. The procedure is applied to concrete specimens that have been in contact with natural sea water from the Mediterranean Sea for 20 years. The specimens are prepared with different binders in different proportions for purposes of comparison. © RILEM 2012.


Andrade C.,Center for Safety and Durability of Structures and Materials | Sanchez J.,CSIC - Eduardo Torroja Institute for Construction Science | Fullea J.,Center for Safety and Durability of Structures and Materials | Rebolledo N.,Center for Safety and Durability of Structures and Materials | Tavares F.,Center for Safety and Durability of Structures and Materials
Materials and Corrosion | Year: 2012

The corrosion of reinforcement can be detected and its evolution quantified through the polarization resistance, Rp, which enables to calculate the instantaneous corrosion rate. In large structures, the determination of the Rp method uses a small counter electrode and the current applied attenuates with the distance, which makes unknown the area polarized. Two main solutions have been applied to overcome this limitation: to use a guard ring (GR) to confine the current to a prefixed area or to measure the bar length polarized by the current. In present work, a 3D numerical simulation is presented using the program COMSOL Multiphysics. Three cases are studied: no confinement, non-modulated confinement, and modulated confinement of the current. In the results, it is illustrated that only when the GR is correctly modulated, the correct homogeneous distribution is achieved and the critical length is well confined in the area below the circle passing underneath the confinement controller electrodes. In a second part, the paper presented the manner to obtain an annual representative value of the corrosion rate through the integration of the instantaneous Icorr values. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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