Concrete floor deterioration?

[thaddeus cox]

Hi again - going for a two-fer today.

I recently moved an old couch that's been sitting in my basement, and found some unusual looking... "stuff" underneath, which appears to be coming up from inside or underneath the concrete floor.

As you can see it pushed up the floor "paint" which has been in place since I bought the house about 10 years ago, forming a kind of bubble which collapsed when I stepped on it.

Any clues what's going on here and whether it is something I should be concerned about? (other than I need to clean my basement...)

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Thanks!

[Scott Patterson]

You can bet it is moisture related or maybe I should say activated. Something was on the concrete floor before it was painted over. I have seen similar conditions when dried urine stains have been covered with paint.

[thaddeus cox]

You can bet it is moisture related or maybe I should say activated. Something was on the concrete floor before it was painted over. I have seen similar conditions when dried urine stains have been covered with paint.
Thanks for the reply Scott.

I meant to include that the more "rusty" of the spots is pretty close to where they apparently had cut a channel for the (copper) oil line to the now-decomm'd oil furnace.

[Scott Patterson]

Thanks for the reply Scott.

I meant to include that the more "rusty" of the spots is pretty close to where they apparently had cut a channel for the (copper) oil line to the now-decomm'd oil furnace.

Old fuel oil seeping out of the concrete? All SWAGS, take some samples to a local lab if you really want to know what is leaching out of the concrete.

[John Kogel]

Pic 2 shows the oil line on the left, I believe? The uplifted sections follow a roughly straight line on a different angle. I suspect you have an old cast iron drain pipe under there that is expanding as it rusts. I don't know why iron expands like that but I know that it does. If you follow that line of rust does it correspond with a floor drain or plumbing drain?
Have your drain system scoped with a drain camera if you need more info. But since the floor is kaka anyway, and the concrete is pretty thin, I would just dig it out a bit, gently with a trowel.
It could be just old abandoned car parts or it could be natural iron. But there is moisture there that is triggering the problem.

[Rick Cantrell]

Pic 2 shows the oil line on the left, I believe? The uplifted sections follow a roughly straight line on a different angle. I suspect you have an old cast iron drain pipe under there that is expanding as it rusts. I don't know why iron expands like that but I know that it does. If you follow that line of rust does it correspond with a floor drain or plumbing drain?
Have your drain system scoped with a drain camera if you need more info. But since the floor is kaka anyway, and the concrete is pretty thin, I would just dig it out a bit, gently with a trowel.
It could be just old abandoned car parts or it could be natural iron. But there is moisture there that is triggering the problem.
I don't know if that is what's happening, but that is using your thinker.