Evolution of reinforcement corrosion due to climatic variations

Concrete moisture is the most significant parameter with respect to its durability, however the data on moisture content in real-size structures are scarce in contrast to the numerous literature published on laboratory experiments. The majority of laboratory tests have been performed in chambers with controlled hydrothermal regime, in general to enable the concrete to reach equilibrium and steady-state conditions. However, real weather induces permanent nonsteady state situations due to the evolution of temperature and climatic events as snowing or raining. Present paper discusses the effect of climatic events on the hydrothermal performance of concrete and their influence on reinforcement corrosion process. Concerning the moisture level, the degree of saturation, S-W, and not the internal relative humidity has been identified to be the controlling parameter of the corrosion process. The psychometric chart and the S-W-RH plots are very suitable to study the hydrothermal behaviour. With respect to the corrosion parameters, corrosion potential, resistivity and corrosion rates, they are very influenced by temperature in a complex manner. The temperature is the main factor influencing the degree of saturation in sheltered conditions while rain and snow are so, in unsheltered ones. In opposition, however, what can be expected, climates with higher temperatures are less aggressive than colder ones, except when rain periods are produced during the hotter periods.