Guideline for service life design of structural concrete -
A performance based approach with regard to chloride induced corrosion
G. van der Wegen1, R.B. Polder2,3, K. van Breugel3
1 SGS INTRON B.V., Sittard, the Netherlands
2 TNO Technical Sciences, Structural Reliability, Research group Building Materials, Delft, the Netherlands
3 Delft University of Technology, Faculty of Civil Engineering and Geosciences, Section Materials and Environment, Delft, the Netherlands
Nowadays major structures require a service life of 100 years or even more. CUR committee VC81 has developed a guideline for service life design based on initiation of corrosion due to chloride penetration for exposure classes XD or XS. A semi-probabilistic simplification of the DuraCrete methodology is introduced with a probability of failure of <10% for corrosion initiation.
Three options are provided to the designer: (1) a range of concrete cover depths adapted to the binder type and exposure class; (2) a semi-probabilistic approach using a safety margin for the concrete cover depth; (3) full probabilistic calculations based on specified input parameters. The guideline permits optimisation with respect to cover depth and concrete composition.
The required concrete performance is the chloride diffusion resistance, measured as Rapid Chloride Migration. Its limit value depends on cover depth, required service life, exposure class and binder type (Portland, Blast furnace slag and Portland/fly ash cement). Model calculations were validated using data from marine and road structures.
Key words: Concrete, reinforcement corrosion, chloride, service life design, performance