A note on limitations of the use of accelerated concrete-carbonation tests for service-life predictions

Concrete carbonation is a process that can limit the lifetime of reinforced concrete structures. The resistance of concrete samples to carbonation is usually determined by accelerated tests under relatively high CO2-concentrations and a fixed relative humidity. No general agreement exists on whether and how the results of these experiments can be extrapolated to a natural setting. This note presents a partial review of existing extrapolation strategies, particularly of explicit prediction formulas. A summary of the problems and limitations which are known from experiments and theoretical modelling is given. Special focus is directed to the different moisture transport characteristics in both natural and accelerated settings. Some strategies are proposed on how to deal with the problems.