On Mathematical Models of Degradation Processes According to ISO 16204 and fib Model Code

The main factors affecting the service life of concrete structures are the presence of chloride ions and carbon dioxide, alternating frost action and mechanical stresses on the structure. In practice, these effects can be taken into account by using mathematical modelling of these phenomena. In this contribution, the authors focus on the processes of chloride ions and carbon dioxide (carbonation process) diffusion through concrete and the associated subsequent corrosion of reinforcement. Mathematical models recommended by the fib Model Code and ISO 16204 are described and the effect of simultaneous environmental and mechanical load on the service life of the structure is discussed. The models are used to study the residual service life of a simple reinforced concrete frame bridge based on the percentage loss of reinforcement area analysis over time.