Assessing the Corrosion Behaviour of Reinforcement Mild Steel in Simulated Coastal Marine Conditions of Walvis Bay, Namibia

The coastal atmosphere of Walvis Bay, Namibia, is among the most corrosive in southern Africa due to persistent marine aerosols, high humidity, and temperature fluctuations. This study investigates the corrosion behaviour of reinforcement mild steel bars (rebars) under simulated marine conditions, using natural seawater and corrosion parameters derived from environmental data of the study area. Unlike conventional studies, this work integrates region-specific exposure data to realistically reproduce the aggressive marine conditions typical of splash and tidal zones. After 60 days of immersion, smaller diameter bars exhibited approximately 64.8% higher mass loss (0.095 ± 0.026 g) than larger bars (0.037 ± 0.001 g), corresponding to corrosion rates of 0.153 ± 0.021 mm/y and 0.076 ± 0.033 mm/y, respectively. SEM and XRD analyses revealed ferrite-pearlite microstructures and corrosion products such as Fe₂O₃, Fe₃O₄, γ-FeOOH, and α-FeOOH, confirming both uniform and localised corrosion. The results are the first publicly disseminated quantitative corrosion dataset for steel rebars in the Walvis Bay marine environment. The use of protective coatings, optimised concrete cover thickness, and periodic maintenance to mitigate steel degradation are highly recommended for reinforced structures in that area. These findings are useful for designing durable coastal infrastructure in Namibia and comparable marine environments. However, there is need for further detailed monitoring of environmental conditions to better understand their influence on the corrosion of exposed steel infrastructures at the coast of Walvis Bay.