Assessment of the behaviour of concrete in the initiation period of chloride induced corrosion of rebars

Reinforcing steel bars embedded in concrete depassivate when a certain amount of chloides built up in their surrounding. In order to reach the rebar, chloride ions have to diffuse through the concrete and then accumulate in a specific amount able to depassivate the steel. In order to predict the time to corrsion onset, both steps, that in a whole are called initiation period for corrosion, have to be taken into account. In this paper, two methods that accelerate the phenomena by the application of electrical fields, are presented: The first one is the so called Multi-Regime Method (MR), that allows the determination of both diffusion coefficients, Ds and Dns, and therefore the binding ability of the matrix. The second one is the Accelerated Integral Corrosion Method (AIC) to determine simultaneously the non steady diffusion coefficient and the threshold value of corrosion of steel. Both methods are reliable, quick, very appropriate concerning cost in hours-man and resources and have been validated in comparison with traditional non accelerated methods.