Assessment and prediction of RC structure service life by means of durability indicators and physical/chemical models

This paper presents an approach to assess the durability of RC structures, with respect to chloride-induced reinforcement corrosion. The approach is based on durability indicators (DIs). First, performance-based specifications, which involve solely DIs, are proposed for concrete mix-design. In addition, within the framework of service life prediction, a multi-level modelling concept is presented, where DIs are the main input data of the various models. A multi-level physically-based numerical model of chloride ingress has been developed within this framework, and is summarized in the paper. The model offers currently three levels of sophistication in saturated conditions and one level in non-saturated conditions: level 1 is a simple chloride diffusion model, level 2 is a multi-species model based on Nernst–Planck equation, level 3 involves transport-chemistry coupling, whereas level 4 is a coupled moisture-ion transport model. Examples of application and validation of the model in lab and in field conditions, in particular in the case of wetting–drying cycles, are given in the paper.