Effect of salt water ageing on the degradation of steel‐composite bonded interfaces

This work aims to investigate the long‐term effect of sea water conditions on the steel‐composite interface. The degradation of the steel‐composite bonded interface was investigated using fracture tests in coupon specimens. Specimens were manufactured and placed for ageing in a salt water solution to simulate the degradation of the bi‐material interface in offshore environment. Four‐point end notched flexure (4ENF) tests were performed to access the interface fracture behavior under quasi‐static loadings. Results of non‐aged and aged specimens show negligible degradation of the interface fracture properties after 69 days of immersion. In addition, steel plates were coated with resin and placed for ageing. The corrosion of uncoated and coated steel surfaces was inspected using optical microscopy. Results showed that the coated steel surface is susceptible to the environmental degradation. This indicates that the steel‐composite interface bonding will degrade after moisture reaches the steel surface.