Rust on Rebar - How much is too much?

[pricklyPete]

As the engineer on a project, I have been asked to inspect some rebar that has been sitting outside for over a year while the project was temporarily on hold. Naturally, the rebar has rust on it in many locations. It is visually evident that there has been no loss of material (which could be addressed by ASTM 615 if that where the concern). The question that I have is if the bond will be affected. Light rust is acceptable, but this term is a subjective. At worst, a very small flake can be peeled off with a fingernail. Does any one have any resources on this topic?

 

[apsix]

This is from a publication found at

http://www.sria.com.au

"Research has shown that the sorting and normal handling and placing of bars removes the loose scale and the remaining rust and bonded scale is not detrimental to the bar bond."

If the rebar is already tied in place I would think about high pressure washing, or otherwise see what it looks like after it has been placed.

 

[bridgebuster]

This came up once before:

http://www.eng-tips.com/viewthread.cfm?qid=207448&page=235

 

[pricklyPete]

Thanks. Not sure why it doesn't come up when I search subject lines for rust.

 

[DWHA]

A lot of it depends on you authority on the project.
Try this, ask the contractor what are we going to do about the build up of rust on the bars. As defined, light scale rust is acceptable. However, you have stored this material outside for much longer than is typically accepted. - This puts it on the contractor, I have experienced that often they have no problem sand blasting or pressure washing the bars.