2012

Vesikari, Erkki; Ferreira, Miguel

Traditional service life design of a reinforced concrete structure is normally based on the performance of concrete when subject to a dominating degradation mechanism. However, this rarely occurs in real-life exposure where reinforced concrete structures are subject to the simultaneous effect of several degradation mechanisms. Practical experience and research results have shown that this is not a conservative approach to SLD. The combination of several degradation mechanisms can result in a shorter service life due to the possible synergetic effects which currently have not been considered in SLD. In this paper an empirical model for the combined effect of frost attack and carbonation/chloride penetration is presented. Based on the results of laboratory exposure tests, the effects of frost attack on the rate of carbonation and chloride penetration as an interacted degradation were developed. In addition, a procedure for service life design based on the use of interaction factors is presented where the synergistic effect of both internal frost attack and frost scaling on carbonation and chloride penetration are considered. Results showed that, if frost attack is rapid, it is usually the dominating degradation mechanism, marginalising reinforcement corrosion initiated by carbonation or chloride penetration. If frost attack proceeds slowly, reinforcement corrosion can become dominant and the interaction effects should be considered in the service life design of reinforced concrete.