In-field performance of North Sea offshore platforms with regard to chloride resistance

Since 1973 a total of 34 platforms for the oil and gas industry, representing 2 650 000 m³ high-strength concrete/high-performance concrete, have been installed in the North Sea. The structures have been closely monitored by the operating companies with regard to their in-field performance. This paper analyses chloride profiles from some 180 cores taken from ten structures after 2–26 years' service. The profiles are applied to assess the remaining service life by modelling. Based on this, the remaining service life as a function of reliability for not passing a critical chloride content at the reinforcement, is directly quantified. The findings are compared with the requirements given in the present Norwegian standards for concrete works exposed to a harsh marine environment.