Influence of Partial Rust Layer on the Passivation and Chloride-Induced Corrosion of Q235b Steel in the Carbonated Simulated Concrete Pore Solution

Abstract

A partial pre-rusted wire beam electrode (WBE) was designed to study the influence of the rust layer on rebar corrosion in the carbonated simulated concrete pore solution (SCPS). The results show that the passive film generated on the pre-rusted steel area is more fragile than that formed on the fine polished steel area in carbonaceous media. Nevertheless, the pitting corrosion resulting from the presence of chloride ions still tends to occur on the fine polished steel surface due to the local acidification process being hindered by the rust layer. The rust layer could play a more important role than the passive film in inhibiting the initiation of chloride-induced corrosion on rebar. The expansion path of the corrosion product would be blocked by the rust layer, leading to the pit propagating in the fine polished region. Furthermore, the growth of pitting corrosion is greatly accelerated due to the catalytic cathodic reaction of the rust layer.

Experimental study on passivation and corrosion performances of pre-rusted steel in simulated concrete pore solution

“…The diffusion of the chloride ions and the carbonation of concrete both could lead to the degradation of the passivation, finally resulting in the local breakdown of the passive film [4][5][6]. Various research works were conducted in the past decades, focusing on the initiation and propagation of pitting corrosion in the concrete pore solution [7][8][9][10][11]. In most of these previous studies, fine polished steel samples were employed.…”