Chloride penetration in concrete under marine atmospheric environment – analysis of the influencing factors

Marine atmospheric exposure conditions provide a severe environment for reinforced concrete structures, mainly due to the occurrence of chloride-induced reinforcement corrosion. This procedure was influenced by many parameters related to the concrete properties and to the environmental condition. In this paper, cubic concrete specimens with 150-mm edge, different types of cementitious material and different strengths, were arranged on a structure, which exposed them to a natural marine atmospheric environment. The purpose was to evaluate quantitatively the influence of different exposure conditions on the durability of concrete, measured in terms of chloride penetration into concrete. Both relative humidity (RH) and temperature were monitored in the experiment. The results indicated that the surface RH and temperature of the concrete were much different from that of the air. The diffusion coefficient and surface chloride concentration were time- and location-dependent, and were influenced by the RH, temperature, and the concrete strength. The results also indicate that error results would be made when using constant diffusion coefficient and surface chloride concentration with the air RH and temperature to predict long-term chloride penetration.