A fully coupled depth-dependent corrosion model for reinforced concrete piles under marine environmental conditions

The corrosion of reinforced concrete (RC) piles in marine conditions demands comprehensive modelling to mitigate risks and enhance structural safety. This study develops a fully coupled, depth-dependent multi-ion reactive corrosion model for RC piles based on poroelastic theory to capture the interactions of chloride ions, sulphate ions, and carbonation across distinct marine exposure zones (atmospheric, splash, tidal, and submerged). Model validation against field experimental data confirms the splash zone as the most vulnerable due to the higher binding affinity of aggressive ions on the surface driven by dynamic exposure conditions. Parametric analysis reveals that increasing cover thickness slightly improves corrosion resistance by delaying chloride ingress, whereas increasing reinforcement bar size significantly improves service life due to a larger exposed steel surface. Additionally, reducing concrete porosity enhances durability substantially by limiting ion penetration, thereby extending service life. Notably, the use of advanced concrete materials, such as high-performance concrete (HPC), self-compacting concrete, and geopolymer concrete can extend service life by up to 80 %. The present study highlights the need for multi-factor corrosion modelling and provides practical design insights for enhancing the durability of marine infrastructure. • A depth-dependent model simulates multi-ion corrosion in marine RC pile structures. • Combined chloride, sulphate, and CO 2 effects are integrated across exposure zones. • Model validated against field data shows splash zone as the most vulnerable region. • Parametric studies reveal the optimal choice of bar size, cover, and concrete type. • Low-porosity concrete like HPC can extend service life by up to 80 %.