Durability performance of an RC beam under real marine all corrosion zones exposure for 7 years

Chloride-induced rebar corrosion is the dominant threat to reinforced concrete durability, whereas its effect mechanism and damage degree are quite variable in different marine exposure zones. Accordingly, a concrete beam was prepared and exposed to marine fields across various corrosion zones for 7 years, and its durability performance (especially rebar corrosion and chloride ion profiles) was evaluated. The results show that the most corroded zone occurred in the high tide level of the tidal zone, and a chloride convection zone of 4 mm emerged concomitantly. Moreover, the rebars were characterized as vertical nonuniform corrosion and localized corrosion, and their corrosion products mainly comprised two outer and inner layers. Therefore, better corrosion protection should be applied to concrete in the tidal zone, when the concrete structure is simultaneously exposed to different corrosion zones. However, the negative impact of long-term marine exposure on the mechanical properties and carbonation resistance of concrete is negligible. In addition, many marine organisms (barnacles and oysters) were found to be subregionally attached to the surface of concrete located in the submerged and tidal zones. Furthermore, they can protect the concrete by forming the shielding layer, delaying the permeation of chloride ions.