Corrosion of steel reinforcement due to atmospheric pollution

The aim of this study is to examine the performance of four different sets of reinforcing steel rebars, S220, S400, S500s Tempcore and S500s Vanadus, exposed to the Greek atmosphere, before their installation into the concrete. The performance against atmospheric corrosion of the aforementioned steel rebars was evaluated by means of microscopy techniques and corrosion rate measurements. In particular, we studied the influence of corrosion products of a set of reinforcement steels on the bond strength between concrete and steel bars, during the hydration process of cement. Furthermore, microscopy techniques and visual observation were used to identify the rust strains and the corrosion product morphology of steel reinforcements before their installation into the concrete. The experimental results shown that the steel type, which exhibits the higher resistance, as far as atmospheric corrosion concerns, was S220 reinforcing steel. In contrary, S500s Tempcore has the least corrosion resistance. The bond strength between concrete and the steel rebars was found to decrease with increasing weathering from 45 to 122 days, due to the morphology and to the thickness of the rust layers formed on steel surface, as observed by the ESEM.