Prediction of corrosion rate in RC structures - A critical review

Corrosion rate is one of the most important input parameters in corrosion-induced damage prediction models for reinforced concrete (RC) structures. Its accurate assessment and/or prediction is therefore required if the damage prediction models are to be reliably used to predict both the rate and severity of damage and to plan for maintenance of these structures. However, it has not been assigned the level of importance it deserves especially with respect to its prediction. In most cases, instantaneous measurements or constant predicted corrosion rate values are used in damage prediction models hence neglecting its time-variant nature while in some cases, salient factors that affect corrosion rate such as cover cracking and concrete quality and not taken into consideration during the model development. The direct consequence of this may be under- or over-estimation of the severity and the time to corrosion-induced damage such as for example cover cracking, and hence service life of the structure. This paper presents a critical review of some of the available corrosion rate prediction models focusing mainly on chloride-induced corrosion. In addition, proposals for the improvement of these models are made.