How long does rebar last in concrete?

[peternap]

I know.....stupid question, but I stay up nights worrying about my foundation.

I really don't care about rebar but I doubted anyone would know how long 1/2" thick angle iron lasted.

[JRR]

Strange!  I worry about the rusting of reinforcement also ... does it fail quickly in concrete under water such as in dams and bridges?

[n74tg]

Even though concrete is relatively porous and allows water to migrate through it, I think the low oxygen environment inside a slab would help prevent the rebar from corroding. 

[MountainDon]

I read somewhere that corrosion is not generally a problem in normal concrete uses like homes. Corrosion of the reinforcing steel can become a problem in roadways and bridges that are subjected to deicing chemicals. That would be way down on my list of things to worry about around the home. Termites or rot would be much more likely to strike first. IMO YMMV

[PEG688]

 Peter I've busted up concrete that was about  / at least 40 to 60  years old , the rebar was always sound. There are other things to fret about , rebar en-cased in concrete  corroding is not one of them. 

So the answer would be, " long enough"!   

[peternap]

Thanks Peg...Now I can get some sleep. It's a little late to do anything about it anyway, unless I want to tear down 2 stories of post and beam framing

I figure in 40 years I'll certainly be in that big barn in the sky ;DI hope

[bobtheengineer]

I wouldn't fret.  Actually rebar in concrete is very stable.  Concrete has a pH of about 10, which creates a very strong passive layer on the outside of the steel. 

The only time when rebar corrosion is an issue, is with an acidic, or choloride environment to eat up the passive layer, and cause a high rate of corrosion.  For environments such as this, they use epoxy coated steel, stainless steel, or even fiberglass rebar. 

[glenn kangiser]

I knew it was something like that, bobtheengineer, but didn't know the specifics.  Thanks for the info and as others have said, Welcome to the forum.

[peternap]

Thanks again everyone!

That darn foundation has caused me more worry than anything else. On the longer poles, I have angle iron anchored in concrete and the post ends resting on the top of the pad. The inner posts are just in gravel and don't concern me.

Everything on the foundation has become a "What if?" issue at some point.

[Billisnice]

I have heard that the rebar in a footing, not a slab, makes an excellent ground for a house. Is that true?

[Redoverfarm]

I noticed something several years ago and always wonder what happened.  Standard re-bar was used in road and bridge construction and suddenly they started using the "green" epoxy coated instead of the regular old black stuff.  I use anything I can get my hands on so it wouldn't matter to me. 

[MountainDon]

De-icing chemicals cause problems with standard re-bar. Chloride compounds are commonly used. The pH changes and then the rebar corrodes badly.

[MikeT]

I have a Ufer rod in my house that is essentially a piece of rebar that was embedded in the footing (in the inside of the wall) and is sticking up, waiting for a grounding wire to be attached via the "special coupling".  It has been flagged as a Ufer rod by my inspector.  I have heard of people accidentally cutting them off, thinking that they were extra rebar.

mt