Repasivation of steel rebars after and electrochemical chlorides removal treatment by simultaneous application of calcium nitrite

Abstract

The Electrochemical Removal of Chlorides (CE) can be proposed as methodology for the treatment of reinforced concrete structures affected by corrosion. This methodology is based on the temporary application of an external voltage between an external anode located on the concrete and the rebar connected as cathode. After the treatment, the extraction of chloride from the concrete level and the repassivation of the rebar are expected. The migration of ionic inhibitors to the rebar could be considered during the connection of an electric field to favour the regeneration of the passive film. In present work a novel methodology is proposed to enhance the efficiency of an Electrochemical Chloride Extraction treatment by simultaneous application of calcium nitrite. A fast repassivation of the rebar is reached after the CE treatment when the inhibitor is applied during the electric field connection. The penetration of the inhibitor near the rebar surface has been confirmed by. The new passive conditions of the steel rebar after the treatment were confirmed by electrochemical measurements. The penetration of the inhibitor near the rebar surface was assured by analysing of nitrite dissolved into the aqueous phase. The presence of nitrite promoted a faster regeneration of the passive film that is maintained in time.