• Zone 1: Submerged - underwater sections of marine piles are continuously exposed to salt water and will become contaminated with chlorides. Despite being highly contaminated with chlorides, submerged sections of reinforced piles are generally less affected by corrosion due to limited oxygen availability.

  • Zone 2: Tidal - the tidal zone is subjected to repeated intermittent seawater exposure and is at increased risk of corrosion due to exposure to chlorides and oxygen. The corrosion rate in this zone is often limited by the rate oxygen can diffuse to the reinforcing steel since the concrete in this zone generally remains saturated.

  • Zone 3: Splash - the splash zone is subjected to occasional seawater wetting. The splash zone is generally at greater risk of corrosion due to regular exposure to chlorides and increased oxygen availability.

  • Zone 4: Atmospheric - The upper sections of concrete marine piles are often above the splash zone and may appear to be less vulnerable to corrosion. These sections however are subject to airborne chloride deposition. It may take more time for chlorides to reach critical concentrations at the reinforcing steel surface, but when this happens, corrosion can be severe as oxygen availability is not limited.

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