Improving the adhesion of zinc coatings used to metallize concrete

Zinc is increasingly being used to metallize steel-reinforced concrete, serving as an anode in the cathodic protection (CP) of the concrete structure. However, for zinc to perform adequately as an anode it must adhere to the concrete structure's surface. A high initial adhesion is needed because the bond strength of any anode coating will normally decrease with time during the application of CP because of anodic reactions at the coating-concrete interface. The less than ideal concrete surface conditions frequently found in the field can make the application of a well-adhering zinc coating very difficult. This work focuses on the arc spray process since it is more cost effective than flame spraying, although the latter is shown to sometimes be preferable.