The approach presented here is an attempt to implement the values of corrosion intensity which have been measured in laboratory tests, in the framework of the service life prediction analysis for corroding structures. First of all, the model on service life suggested by Tuuti was considered, and only the propagation period model has been analyzed in this paper. In order to expand the proposal, different steps were covered: (1) the definition of an unacceptable level of deterioration, taking into consideration the levels suggested by the Comite Eurointernational du Beton (CEB) in its Bulletin No. 162, in order to define the urgency of intervention in a damaged structure; (2) the reduction in bar diameter or bar section was taken as the determining parameter in failure risk, assuming that this decrease in section occurs either in a generalized form or in the zones of the structure in which the load-carrying capacity may be significantly affected; and (3) the ranges of possible corrosion intensity values were introduced in Tuuti's model for calculating the reduction in bar section in function of the life of the structure. Some examples for bars of 10 and 20 mm were presented. Finally, the limitations and the improvements of the proposal are discussed.