Based on the outcome of the preliminarily experiments that have been carried out so far, it is observed that the chloride-induced depassivation of steel preferably starts in local zones where physical or chemical differences from the surrounding media are obvious.

These local sites can be in the form of defects or crevices on the steel surface; chipped or cracked parts of the epoxy on the steel surface for example can be considered to be ideal locations for becoming preferred local depassivation zones. Similarly, non-uniform mill scale on the steel surface might even create these local effects. In addition, since the interface of rebar surface and surrounding concrete hosts large number of voids and microcracks (some of these are natural concrete voids, but others are large voids that are produced during the pouring of concrete, over vibration or mix settlement), the formation of local zones on the surface of the steel is particularly unique in reinforced concrete.

Although the experimental investigation of this local sites is rather difficult since these local sites are very small and hard to isolate, numerical studies can be used to test and understand the phenomenon. Ion movements and resulting changes in the pore solution composition in the presence of local crevices on the steel surface can be modeled through the solution of the governing differential equations by the finite element technique which is currently in progress.