Splitting cracks as performance indicator for existing structures, part 2

Research Project, 2024 – 2026

The project is a direct continuation of an earlier project with the same name, addressing the need for suitable performance indicators for structural safety in a changing climate. We must understand, model, and quantify the underlying physical mechanisms to predict safety in a changing future. Climate change will mean both higher average temperatures and more frost cycles, especially in areas where many roads will be opened to heavier loads. Therefore, how the combination of corrosion and frost affects safety becomes essential. In the first part of the project, experiments showed that pre-cracked specimens lost a significant part of their residual strength when subjected to frost cycles submerged in water. Therefore, crack widths will be affected by frost, which needs further study. Furthermore, we have managed to quantify several important parameters, such as the free volume increase of rust, internal deformations and cracking of the specimens, and the corrosion attack on the steel.  
In this project, we will continue to evaluate experiments quantifying the transport of corrosion and how it is affected by cracks. These results will be used in analyses, allowing us to calibrate previously used models of corroding reinforcement much better. Furthermore, experiments with combined corrosion and frost will be carried out, and the effect on cracks and the bond between reinforcement and concrete will be studied. The final result is an improved proposal on how splitting cracks can be used as a performance indicator for existing concrete structures. With this increased knowledge, we can repair and replace existing structures only when necessary, with continued guaranteed load-carrying safety.