From corrosion rate to accumulated corrosion depth or loss in cross section of reinforcements
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.