Corrosion Index

[Stues]

I apologize for not having adequate reference materials, but I am not able to find a suitable explaination of corrosion index. I have a bridge that has been specified to have its members have a corrosion index of 5.8. The supplier proposes weathered steel that has an index of 6.0. Although I recognize this is adequate, I'd like to understand what is. Thanks in advance.

 

[DrCol]

ASTM G101 refers to the corrosion index for weathering corrosion on steel: A good explanation can be found at

http://iti.acns.nwu.edu/projects/hsla.html