Corrosão de armaduras em concreto armado: o processo, causas e técnicas de mitigação

Abstract

The corrosion of reinforcing steel in reinforced concrete structures constitutes one of the main degradation mechanisms, directly affecting the durability, safety, and service life of constructions. This study presents an analysis of electrochemical corrosion mechanisms, addressing depassivation processes resulting from carbonation and from the action of chloride ions, as well as their structural effects. The structural and economic consequences associated with corrosion are analyzed, such as cracking of the concrete cover, loss of steel–concrete bond, reduction of the effective load-bearing cross-section, and increased repair and maintenance costs. Moreover, the determining factors for the progression of corrosion are discussed, including concrete properties, water-to-cement ratio, curing conditions, the presence of cracks, and environmental variables. The study also encompasses the main diagnostic and monitoring techniques, such as the determination of concrete mechanical strength, carbonation depth, electrical resistivity, identification of chlorides in concrete, corrosion potential analysis, and linear polarization resistance. Furthermore, the principal mitigation and rehabilitation strategies are addressed, highlighting electrochemical techniques (cathodic protection, desalination, and realkalization), the use of inhibitors, and the application of metallic and non-metallic coatings. Finally, it was verified that corrosion results from the interaction of environmental, physicochemical, and construction-related factors; directly impacts the structural behavior of reinforced concrete and generates economic losses; carbonation is related to factors that govern concrete permeability; chloride ions are the most aggressive agents, causing intense and localized corrosion; diagnostic techniques are essential for the development of effective mitigation strategies; and the rehabilitation plan is established according to the specific characteristics of each case.