Abstract
The potential of passive steel embedded in concrete is a key parameter on the value of the chloride corrosion threshold. The phenomenon of a potential-dependent chloride threshold (PDT) along with the corrosion macrocell coupling between active and passive steel assembly components allows to combine a corrosion initiation-propagation model to forecast the durability of reinforced concrete structures in marine service. Initial calculations using a one-dimensional and deterministic corrosion initiation-propagation model incorporating PDT resulted in lower damage development in an aged system than when using the traditional value of fixed chloride threshold (PIT) assumption. In contrast, for early stages of corrosion damage the relative effect tended to be in the opposite direction. These diverse outcomes are explained by the interplay between delayed corrosion initiation and concentration of corrosion when it is localized. An expansion of that PDT forecast model case is presented with emphasis on establishing the model output sensitivity to the choice of model input parameters, primarily to reveal the extent of the macrocell interaction between anodic and cathodic regions under various system conditions. The concrete parameters were: resistivity, oxygen diffusivity and chloride diffusivity, representing values comparable to those encountered in the field plus some extreme conditions, especially at the low resistivity end. A comparison with the traditional PIT approach was also examined.
