Assessment of Corrosion Behaviour of Mild Steel Reinforcement Bars in Coastal Environments of Bayelsa State

This study investigates the corrosion behaviour of mild steel reinforcement bars exposed to the coastal saline environment of Bayelsa State, South South Nigeria. Coastal structures in the Niger Delta are among the most vulnerable to reinforcement corrosion due to the combined effects of chloride ion penetration, high humidity, and elevated temperatures, leading to premature structural degradation. The study adopts a laboratory and field-based experimental methodology in which mild steel rebar specimens are subjected to accelerated salt spray corrosion testing and natural immersion in seawater samples collected from three locations in Yenagoa and Brass. Corrosion rate is measured gravimetrically at 2, 4, 6, and 8 week intervals. Surface analysis is conducted using scanning electron microscopy to characterise the morphology of corrosion products. Electrochemical impedance spectroscopy is applied to assess passive film stability on selected specimens. Findings reveal corrosion rates significantly exceeding those reported for comparable inland environments, with chloride-induced pitting identified as the dominant damage mechanism. Corrosion product analysis confirms the formation of akaganeite phases characteristic of chloride-contaminated steel. The study demonstrates the insufficiency of bare mild steel rebar in aggressive coastal exposure and recommends epoxy-coated or stainless steel alternatives for structural reinforcement in Bayelsa State coastal construction. Keywords: corrosion, mild steel, reinforcement bars, coastal environment, Bayelsa State.