The present study concerns the electrochemical treatment to increase the resistance against chloride–induced corrosion of steel in concrete, which was ensured by a microscopic examination and corrosion tests. The current density (DC) applied to the embedded steel immediately after casting of concrete ranged 125, 250 and 500 mA/m² for two weeks. As a result, an increase in the current density resulted in an increase in the precipitated calcium hydroxide at the steel–concrete interface within 100 µm from the steel surface, which would enhance the buffering capacity to the corrosion reaction. However, an application of the electrochemical treatment did not always impose the benefit in raising the corrosion resistance: the surface chloride content, when the concrete specimens containing the steel embedment was exposed to a salt solution, was increased, presumably because of modification of the chemistry at the right surface of concrete. Notwithstanding, the critical chloride ranged 0.88, 1.21 and 1.76% by weight of cement for the current density of 125, 250 and 500 mA/m² respectively, while untreated specimens indicated only 0.62%. Consequently, the electrochemical treatment increased the corrosion–free life by enhancing the resistance to corrosion, resulting from the formation of precipitated calcium hydroxide at the steel–concrete interface.
Keywords: electrochemical treatment, calcium hydroxide, porosity, critical chloride content, steel corrosion resistance, concrete structures, calcium hydroxide, steel–concrete interface, chloride–induced corrosion