1. Reinforcement corrosion

Concrete is a material whose constitution is not stable and evolves over time. From a global point of view, this transformation leads to dimensional changes at the element level. As regards the structure of the internal composite, on macro and microscopic scales, the hydration compounds of the binder are the subject of different combinations. As we shall see in the next paragraph, concrete is heterogeneous and diffusion phenomena are complex. Void spaces (pores and capillaries) containing air or various solutions play a major role in the solidification process of the crystals making up the binder phase, which enclose and ensure bonds with inert aggregates.