Chloride Penetration Profiles in Marine Environments

Abstract

The chlorides from the sea and the marine breeze are the main source of corrosion in marine environments. Their penetration into concrete occurs through capillary absorption, diffusion or a mix of both. A chloride threshold for producing reinforcement corrosion can be predicted through mathematical models but the results may not be reliable if the action of environmental agents as the RH, temperature, winds, rains and drying periods are not well known. Although these limitations are recognized in several works, there are few field data in the literature to support, according to different exposure conditions, the form of the chloride penetration profiles. This work presents the form of chloride profiles from different exposure conditions. It discusses their behavior and justifies the results according to the presence of the environmental conditions. Some of the results indicate that the environments with chloride saturation produce profiles with a well defined concentraion gradient, while those with strong periods of rains, drying, winds, as well as strong variations of RH and temperature show a two-zone profile. In the last case, one zone is close to the concrete nucleus where the supposed reinforcement is positioned and that stays dampened due to the high chloride concentraion, and the other one is close to the concrete surface in which continuous wetting and drying cycles take place. It was also found that, under this research trial, the chloride penetration mechanism did not change with the micro-climate but nucleus concentration changed with the distance from the sea and concrete quality.