The major degradation mechanism in concrete structures is the corrosion of the
reinforcements as a result of chloride penetration. The corrosion reduces the
serviceability and safety of structures because of the cracking and spalling of
concrete and loss of the steel cross-section. Recently, service life design has moved
from being prescriptive to model- and performance-based. The current approach
aims at postponing the initiation of corrosion until the end of the required service
life with a predetermined reliability. This is based on the simplified modeling of
transport in uncracked concrete and testing of laboratory samples for chloride
diffusion.