Partially Built Abandoned Concrete Structure

[Jimbio7]

I've been asked to review an existing multistory concrete structure that was left unfinished for 13 years. Client wants to know if the building is salvageable. All of the above grade walls, columns and slabs have been exposed to Canadian winter freeze and thaw without any air entrainment or other protection. Presumably no chlorides.
From a previous survey done and a review of the slab condition, it does not appear that differential frost heave has occurred at the interior pile foundations, either due to the weight of the structure or friction of the piles below frost.
At this point, all I want to know is if there are any code provisions or industry suggestions that would make the concrete unsuitable for use after being left for so long in an exposed condition. Something that we wouldn't be able to observe using core samples and visual reviews or any other testing you would do for an old parking garage. My research is coming up empty.

 

[BAretired]

Apart from what the code may say, do you trust the work done to date by the contractor? Do you know who the contractor was? Do you have or can you obtain drawings for the project? Would you be willing to assume responsibility for the structural work done to date?

 

[Jimbio7]

Original developer stopped paying the contractors though I don't know who the GC was. Current owner who acquired it wants to sell it now so needs to warrant that it isn't just a teardown. From what is visible, workmanship seems OK. We will be getting the existing drawings.
My main question is assuming we (or a different engineer who does take responsibility) reviewed all the existing information and did testing that would satisfy us that the building is ok structurally (including necessary repairs or upgrades), does the fact that it has been sitting exposed for 13 years cause any code issue or significantly reduce the expected lifespan of the underlying structure such that it isn't worth salvaging? Someone (don't know who) told the client that concrete exposed for more than 10 years is unusable?

 

[Enable]

We used to regularly pour CIP parking garage slabs with no waterproofing or protective coating. Those were exposed for decades in unheated garages with people driving on them with all sorts of contaminates (e.g. salts). If it's salvageable will depend on the current condition and nothing else.

That said, I would be surprised if concrete is actually in okay shape if it wasn't intended to be exposed. That's a long time for non-air entrained concrete to sit! I would definitely be scanning and taking loads of cores.

 

[BAretired]

Someone (don't know who) told the client that concrete exposed for more than 10 years is unusable?

That is not something we can take to the bank.

If a structural engineer inspects the building and runs whatever tests he deems necessary, and declares the existing structure to be adequate for continued use, I don't believe the building code would enter the picture. If the authority having jurisdiction disagrees with his declaration, based on comments, complaints, opinions of neighbors or any number of other concerns, there could be an ongoing battle, the results of which can only be guessed.

 

[dik]

I think freeze thaw has a greater effect on wetted concrete. If it was dry then there are likely no issues. Best to check in areas that could have received water. You can also have an investigation undertaken by a company that specialises in concrete testing. As far as frost heave... it's often a problem that occurs in some locations. Ice lenses can build up and create substantial heave... often this doesn't happen. I recall a paper of decades back where they have found supercooled water at -40 (doensn't matter if C or F) in clays. The clay is so tight that the water cannot do a phase change, so it stays in a supercooled state.

If it has not deteriorated, there is a reasonably good chance it is OK. Just a matter of doing a little NDT and observations.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JoelTXCive]

I would think that you could reach a rational decision on the building being usable or not.

You could have the client hire and pay a testing company to take cores and write a report on the condition of the concrete.

Then, assuming old plans are available; you can write a report on the structural condition of the building and reference the report on the condition of the concrete.

For most of our clients, we make them hire and pay the geotech; and then all of our contract language and PS&E documents state that we are relying upon XYZ's geotechnical analysis for our structural design.