Evaluating the Protection Effect of Galvanized Coatings on Reinforcing Bars for Concrete

摘要

Reinforced concrete structures exposed to severe environments are susceptible to corrosion, decreasing substantially its service life performance. To avoid such deteriorations, the use of protective coatings to the reinforcing steel bar, also called rebar (i.e. galvanizing), is increasing in the last two decades. The galvanizing process is the formation of a metallic layers (zinc, Zn, and iron-zinc, Fe-Zn, alloys) on the steel surface. This metal not only works as a physical barrier, but also acts as a galvanic anode protecting to the steel, from corrosion. This galvanic mechanism of Zn on alkaline media has some drawback as for how long it will last if Zn also corrodes in alkaline media, before hazardous chemicals (i.e. chlorides and CO_2) reach the embedded steel. In this work, some defects were created on galvanized rebars in order to evaluate the sacrificial effect of Zn and the effect of chloride addition.