Guideline for service life design of structural concrete with regard to chloride induced corrosion - The approach in the Netherlands

Nowadays the market calls for concrete structures with 80, 100 or 200 years life without major maintenance. To meet this call, CUR committee VC81 has developed a guideline for service life design based on initiation of corrosion due to chloride penetration for exposure classes XD and XS. A semi-probabilistic simplification of the DuraCrete methodology is introduced with a probability of failure of ≤10% for corrosion initiation, based on experience gained with two large tunnels and structures in the High Speed railway line. The required concrete performance is the chloride diffusion resistance, measured as Rapid Chloride Migration (RCM). Its limit value depends on cover depth, required service life, exposure class and binder type (Portland, Blast furnace slag and Portland/fly ash). Model calculations were validated using data from marine and road structures. Three options are provided for specifying a maximum RCM value: (1) a range of concrete cover depths adapted to the binder type; (2) a semi-probabilistic approach using a safety margin for the concrete cover depth; (3) full probabilistic calculations based on specified input parameters. Quality control based on concrete resistivity measured using the Two Electrode Method is proposed. The guideline permits optimisation with respect to cover depth and concrete composition.