Figure 16. Exposed steel reinforcement due to 

 spalling of concrete cover. 



Corrosion of steel reinforcing can also result from stray electrical 

 current or corrosion cells that develop on the embedded steel. Electrical 

 potential differences can occur in various spots in concrete containing 

 metals because of differences in moisture content, oxygen concentration, 

 electrolyte concentration, and by contact of dissimilar metals. A corrosion 

 cell results when regions of different electrical potential are intercon- 

 nected by a conductive pathway. Loss of metal then occurs at the region of 

 more positive potential (anode) . 



One recently developed method of preventing reinforcing steel deteriora- 

 tion is to coat the bars with an epoxy material. The epoxy is applied in 



106 



