Effect of coarse aggregate size on corrosion of reinforced concrete exposed to carbonation and chloride ingress by electrochemical measurements

Abstract

This article evaluated the application of electrochemical techniques to assess the degree of corrosion of reinforcement steel in concrete exposed simultaneously to carbonation and chloride ingress. After carbonation accelerated at 3 different levels, the reinforcement corrosion was accelerated by the ionic migration of chlorides. Subsequently, the electrochemical techniques (Rp, cyclic voltammetry, EIS) were applied to the specimens at 40 months of age. Chloride penetrations above 20 mm showed a remarkable drop in steel durability. In this condition, the disappearance of the stability region in the voltammograms and an increase in the capacitive arc of the impedance spectra were identified. The intensification of carbonation reduced the Rp. Concretes with 25 mm coarse aggregate had the worst results in the electrochemical tests since the sharp drop in the phase angle during EIS tests indicates a concrete/reinforcement interface incapable of retaining electrical charges, with a low resistance to corrosion progress. The results of mass loss supported this statement.