Performance parameters for the durability design of reinforced concrete structures with stainless steel reinforcement

Stainless steel reinforcing bars can be a suitable choice to guarantee the target service life of reinforced concrete structures exposed to aggressive chloride-bearing environments. Usually, the choice of the stainless steel grade is based on experts’ opinion or practical codes, whilst the adoption of performance-based approaches would allow to quantify the service life. To apply these models, when stainless steel reinforcement is used, the evaluation of the parameter which describes its performance when used in a chloride-bearing environment, i.e. the critical chloride threshold for the initiation of corrosion, is an indispensable requirement. This parameter cannot be easily determined since it is influenced by many factors and a standardised methodology for its evaluation has not been proposed yet. This paper describes the results obtained in an experimental research aimed at developing a test methodology which allows to evaluate the cumulative density function of the critical chloride threshold for the corrosion initiation. A test procedure based on mixed-in chloride and potentiostatic polarisation was proposed and applied to a duplex stainless steel reinforcement (1.4362). Corrective factors, which have to be applied in order to use these data for the design of structures in different exposure conditions, are discussed.