Assessing freeze-thaw performance of concrete: Some considerations

Due to the variability of environmental loading, concrete is seldom subject to the effect of a single deterioration mechanism. The possible synergetic effect of two or more deterioration mechanisms, acting simultaneously or intermittently, affects the deterioration rate resulting in service life predictions remarkably different from expected. In Finland, the most common deterioration mechanisms affecting concrete are freeze-thaw and reinforcement corrosion due to both concrete carbonation and the ingress of chlorides. This paper provides a brief glimpse of research conducted at VTT Technical Research Centre of Finland Ltd., on the effect of combined deterioration mechanisms on concrete durability performance. The scope of the research has been broad, i.e., for example evaluating how cracks resulting from freeze-thaw deterioration influence chloride ingress; how freeze-thaw cycles without cracking assist chloride transport in the concrete; or how carbonation changes the surface properties affecting freeze-thaw scaling. Results are based on both accelerated laboratory testing and in-situ exposure testing from field stations. The research results show that a holistic approach to concrete durability performance should be taken into account when estimating the service life of concrete structures