Concrete realkalization subject to carbonation: Systematic review of the literature on treatment methods, efficacy and reaction mechanisms

Chemical realkalization (CRA) and electrochemical realkalization (ERA) are procedures used to repair concrete structures subject to corrosion in reinforcement due to carbonation. The premise is to raise the pH of the concrete pore solution, with the aim of restructuring the passive film of the reinforcement. RAE has been applied to structures for 40 years and is effective in restructuring the passive film. The CRA is a little discussed method in scientific circles. This paper synthesizes information on these methods, through a Systematic Literature Review (SLR) and snowballing technique, with the adherence of 24 works where the main methods of applying treatments, alkaline solutions and physical-chemical reactions. A comparative analysis was carried out between ERA and CRA, although being governed by different mechanisms both raised the pH of the carbonation front to a value higher than 12, were effective in a period less than 15 days, and were also capable of restructuring the passive film of reinforcement in systems with mass loss due to corrosion below 0.25%. The main gaps are CRA reaction mechanisms, changes in concrete properties, duration of both treatments and greater predisposition to the alkali-aggregate reaction after treatment.