Análise do comportamento do aço galvanizado frente à corrosão por cloretos e seu efeito na aderência

Abstract

Hot-dip galvanized steel is widely used to control corrosion in reinforced concrete structures exposed to aggressive environments. Hence, to analyze its behavior, considering the conditions of the environment and the corrosion process is important. The literature presents uncertainties in these field and there is lack of studies on the influence of corrosion of galvanized steel on its adherence to concrete. Thus, the aim of this study was to investigate the electrochemical behavior of galvanized steel against corrosion and its effect on the bond strength to concrete. For the first analysis, there was made cells containing steel bars (galvanized and non-galvanized) with 8 mm of diameter submerged in saturated solutions, which simulated the liquid phase of concrete. The steel behavior was evaluated by monitoring the cells using electrochemical techniques. For the second analysis, specimens composed of a concrete cube with a steel bar (galvanized and non-galvanized) of 10 and 20 mm located in the middle with a defined length of adhesion were used. Adhesion was evaluated using the pull-out test, followed by measuring the degree of corrosion of the steel. The result has shown that the zinc coating acts as a barrier against corrosive agents and has a performance that is indifferent to concrete carbonation, maintaining high corrosion resistance. It was also found that the initial corrosion of galvanized steel due to the high alkalinity of fresh concrete does not affect the structural performance of reinforced concrete and that galvanized steel has superior bond strength to concrete than non-galvanized steel for small corrosion rates. Nevertheless, it decreases as the corrosion rate increases.