Chloride ingress measurements and corrosion potential mapping study of a 24-year-old reinforced concrete jetty structure in a tropical marine environment

Abstract

A corrosion survey was made of a 24-year-old reinforced concrete jetty structure in Woodlands, in the northern part of Singapore. This particular jetty structure was selected for the field survey since it was already showing signs of reinforcement corrosion and deterioration. Two piles which were located near the stairs (and were easily accessible) were surveyed in detail. The survey covered the mean tidal zone, the upper tidal zone at 0·8 m above the mean tide level, and the splash zone at 1·3m above the mean tide level. The principal test methods used in the survey were chloride profile analysis and corrosion potential mapping. A general visual and de lamination survey was also carried out. The chloride content in the concrete increased with height above the mean tide level. Chloride diffusion coefficient values, which were calculated from the chloride profile measurmounts, ranged from 2·13 × 10-8 cm2/s athe mean tidal zone to 5·50 × 10 8 cm2/s at the splash zone. The upper tidal and splash zones, i.e. those with the highest chloride content, were found to be most susceptible to corrosion. The corrosion potential measurement was reasonably consistent and reliable method for monitoring and assessing the level of rebar corrosion.