Abstract
Chloride-induced steel corrosion is the most concerning issue for the durability of concrete structures. Concrete and steel samples were obtained from a 30-year-old reinforced concrete bridge. The chloride content was measured by a potentiometric titration method and the microstructure of concrete was obtained by scanning electron microscopy and mercury intrusion porosimetry. The rust phases of the steel were detected by X-ray diffraction and Raman analysis. It was found that the convection depth for chloride transport in cracked concrete was significantly larger than that in uncracked concrete. The concrete in a pier column facing upstream had greater porosity due to the water impact and calcium leaching. The coefficients of variability of chloride diffusivity of concrete for the bridge deck and the pier column were significantly different. Rust phases including lepidocrocite, goethite, akaganeite, magnetite, and maghemite were detected using Raman spectroscopy and X-ray diffraction. The major phases of steel rust in the atmospheric zone were lepidocrocite and goethite, while they were lepidocrocite and maghemite in the tidal zone. The results of this study would provide information concerning the chloride-induced steel corrosion under a marine environment in order to predict long-term behaviors of a reinforced concrete structure.
Highlights
The degradation of reinforced concrete (RC) structures in a marine environment is related to physical and chemical processes including chloride penetration, sulfate attack, and carbonation.Among these factors, chloride penetration is The most concerning for The durability of concrete structures [1,2]
Costa and Appleton [3] studied concrete structures exposed to a marine environment in Portugal and found extensive deterioration due to chloride-induced corrosion of The reinforcement
The results showed that chloride accumulation first increased and decreased as The drying time increased. in addition to chloride from seawater, atmospheric chloride in The marine environment accumulates on concrete surfaces and slowly diffuses into The concrete [11]
Summary
The degradation of reinforced concrete (RC) structures in a marine environment is related to physical and chemical processes including chloride penetration, sulfate attack, and carbonation. Poupard et al [25] tested steel bars in a RC beam in a marine environment by X-ray diffraction (XRD) and μ-Raman analysis They identified α-FeOOH, β-FeOOH, Fe3 O4 , and maghemite (γ-Fe2 O3 ) as corrosion products. Otieno et al [33] compared chloride-induced corrosion of beam specimens exposed to accelerated laboratory conditions (cyclic wetting and drying) and a filed marine tidal environment. In The previous study on The steel corrosion embedded in concrete, most of The work has been carried out in The laboratory under accelerated conditions, due to The slow processes of corrosion under a natural environment. The chloride profiles and steel corrosion were studied in The atmospheric and tidal zones for a 30-year-old concrete bridge in a marine environment in Shenzhen, China. Corrosion products of steel in The atmospheric and tidal zones were identified by XRD and Raman analysis
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
