Cracks and reinforcement corrosion

Research Project, 2023 – 2026

In current codes, the crack width on the concrete surface is limited, as a way to try to avoid or at least delay reinforcement corrosion and thus obtain durable structures. There is also a large focus on cracks and crack widths at inspections of existing structures. However, despite major research efforts, the effect of cracks on durability is debated. We know that in a chloride-containing environment, there is a greater risk for pitting corrosion at transverse cracks. However, the corrosion pits seem to grow at a slower rate over time, while they increase in number. These observations have major implications for the structural safety, as corrosion patterns with few, deep, narrow pits are significantly more detrimental than many scattered, shallow pits, both for load-carrying and deformation capacity. The corrosion process is affected by the self-healing of cracks and by the appearance of corrosion-initiated cracks. In this project, the complex interaction between transverse cracks, corrosion damage and corrosion-initiated cracks will be investigated. We will conduct long-term tests, designed to complement existing test results, and supplement an existing database with additional information from the literature. The results will be analyzed, both through physical modelling of the entire corrosion process, and with statistical methods where we investigate how cracking correlates with measured corrosion attacks. The project will be carried out in collaboration between Chalmers University of Technology and the Norwegian University of Science and Technology. The main result from the project will be knowledge about the effect of cracks on corrosion. This is fundamental both to be able to set reasonable requirements for new construction, and for improved maintenance planning of existing structures. Thereby, the project contributes to reducing the use of resources and to lower life cycle costs for concrete structures.