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.