2. Two stages in steel corrosion: incubation and propagation

The visible signs of corrosion on a structure (rust stains, cracks, exposed corroded reinforcement, concrete spalling) are the consequences of endogenous chemical reactions that began long before the damage became apparent.

• Incubation and propagation: the process

  Schematically, there are two successive phases in the development of corrosion.

• A priming period, also known as the "dormant period", "incubation period" or "initiation period", during which the stability of the system consisting of the metal reinforcement embedded in the cement matrix of the concrete progressively decreases, creating conditions conducive to the development of corrosion.

• A propagation period during which, first and foremost,...