Concrete durability based on coupled deterioration by frost, carbonation and chloride

Concrete performance is traditionally assessed based on deterioration caused by a single mechanism. Yet in field performance, concrete is actually being affected by simultaneous environmental and conditional exposures, possibly with synergetic effect on the degradation rate of concrete. In this paper, the results of a Finnish research project based on assessing coupling deterioration mechanisms are presented. For instance, evaluating how cracks resulting from frost attack influence chloride ingress, or how carbonation changes the surface properties and thus may affect frost-salt scaling and chloride penetration. The research project built on 30+ years of concrete durability research, including 10 years of field station studies. The durability performance was assesses with both accelerated laboratory testing and in situ exposure results from field stations, to more realistically predict long-term performance. All the results together with local weather data served as a basis for thorough modelling, computer simulation and development of service life models. The project was composed of an extensive laboratory testing regime, in parallel to the exposure of several concrete specimens at field stations, also subject to periodic testing. Testing was based on standardized methods, taking into account the effects of ageing and repeated exposure cycles to different conditions as well as field studies. More than 60 different normal strength concrete mixtures were evaluated with a range of cementitious binders and air contents. The final stage of the project addressed improving service life prediction tools based on the laboratory coupled deterioration results. The project results quantitatively support the hypothesis that a holistic approach should be taken to predicting deterioration. The project has addressed improving service life prediction tools based on the laboratory coupled deterioration results and field testing.