Impact of mechanical loading on the corrosion of steel reinforcement in concrete structures

This paper presents results of an experimental investigation on the effect of mechanical loading on the corrosion of steel reinforcement in concrete. Reinforced concrete beams were cast, subjected to mechanical loadings and then exposed to corrosive environment. Successive drying and wetting cycles using 3% sodium chloride salt solution were used to accelerate the corrosion attack. Electrochemical techniques such as macrocell corrosion current, linear polarization resistance (LPR), corrosion potential (Ecorr) and electrochemical impedance spectroscopic (EIS), were used to evaluate the corrosion behavior of the reinforcement. Also, chloride penetration profile and visual inspection of the beam rebars were obtained. The results shows that the pre-exposure mechanical load has no influence on the corrosion initiation or corrosion rate thereafter, unless it reaches to some limit where it develops connected cracks through which the chloride ions flow and depassivate the rebars. The load of 25% of the ultimate capacity seems to be the critical load limit where some microcracks onset to be connected, facilitate the chloride ions flow, and initiate the rebar corrosion.