Impacts of global warming and variable airborne chloride exposure on concrete structures in Hokkaido, Japan

Global warming has become a threat to human societies due to its myriad and complex impacts. Among these are sea level rise and climate change, which carry significant implications for the life-cycle management of concrete infrastructure in coastal areas due to unforeseen changes in chloride exposure, which may lead to uncertainty about structural safety. This may be attributed to the inability of chloride diffusion prediction methods to account for temporal changes in exposure, as conventional methods assume a constant surface chloride ion concentration. However, it may be expected that, due to changes in airborne chloride exposure as a result of global warming, the surface chloride concentration is not constant over time. It is therefore necessary to account for its impacts in the life-cycle management of concrete infrastructure by considering temporal changes in the exposure to airborne chloride. In this study, a method is developed that facilitates the prediction of chloride penetration into concrete under non-constant surface chloride concentrations, which are estimated from the airborne chloride exposure based on sea wind ratio, wind speed, and distance from coastline. The impacts of global warming on chloride diffusion are then estimated at a specified coastal location in Hokkaido, Japan, over a 50-year period using forecasted climate data and simulated sea level rise. Although the numerical simulation results did not find that the chloride con- centration limit necessary to initiate corrosion will be reached in even the most severe prediction scenario, variability in the surface chloride concentration may reduce the safety factor against chloride-induced corrosion, as not considering the effects of global warming may lead to underestimating the actual chloride exposure.