has been presented by Mozer, et al.^^ Steel cast in concrete quickly 

 develops a passivating iron oxide film that prevents further corrosion. 

 Passivation of the steel is provided by the high alkalinity (pH 12.8) of 

 lime produced by the hydration of cement." Corrosion of rebar occurs if 

 failure (cracking) or porosity of the concrete allows chloride ions 

 (electrolyte) to penetrate ot the surface of the rebar, and depends also 

 on other factors such as the availability and concentration of oxygen, and 

 number and size of voids adjacent to the rebar. -'-^ Figure 1 is a schematic 

 representation of the conditions at the rebar surface when an electrolyte 

 penetrates and forms an electrolytic macrocell in the concrete. -'--'- 



PENETRATION OF OXYGEN AND CHLORIDE IONS 





IMPERMEABLE 5y.C:D?lri^ °%°°, 





.POROUS CONCRETE 



^J^ PASSIVATION 

 ^•p^cOF STEEL 





oy^\ 



CATHODIC AREA 



FORCEMENT 



ANODIC AREA 



CATHODIC AREA 



LOSS OF PASSIVATION BY CHLORIDE, 

 RUSTING, AND EVENTUAL 

 SPALLING OF CONCRETE 



Figure 1 - Electrolyte Macrocell in Reinforced 

 Concrete Causing Spalling 



Corrosion resistance may be enhanced by metallic (i.e., zinc or 

 nickel) coatings on rebar embedded in concrete submerged in seawater. In 

 reviewing the technology, Lorman-'--'- noted that long-term tests have revealed 



