Found black foam material under carpet I'm replacing

[Lollyloopp]

Found a black foam substance glued to concrete after removing carpet. Pulls up easily where it is the thickest.
In researching I found black mastic cut back adhesive that might have asbestos and left over backing from rubber backed carpet. How can I definitely tell the difference?
What I have is soft foamy material that is flexible, not hard or rigid. It does crumble out tear apart easily.

Also, best way to remove this stuff, especially where it seems really stuck to the concrete?

I already laid a vinyl plank floating floor over it with an underlayment. The floor came apart after a few months. The click lock just failed miserably, I think because of the unevenness from this black stuff.

 

[C.J.]

The only way to check for asbestos is to send a sample off to a lab to have it examined. Assuming it’s not hot, a 4” razor scraper is usually the quickest way to scrape that foam backing up.

 

[Don Monfils]

Sounds like it was a rubber back carpet.
The black rubber should be able to be scraped off with a stand up scraper or even an ice chopper. You can buy an inexpensive 4 inch wallpaper scraper, but then your working on you hands and knees.

 

[rugaddict]

What you have there is the classic black rubber from a glued down rubber back carpet circa 1980—- glue would be hard—-rubber would be soft—- that is why the click failed—-too soft too much movement—-I use a razor scraper to take it up—-labor intensive—-very messy—-that’s why the last people chose to avoid it

 

[Lollyloopp]

Thank you for the reassurance!
Do I need to scraper EVERYTHING of the concrete? There are remnants of the adhesive under the rubber backing. Would this also cause the floor to fail? The laminate floors have done fine with the small amounts of adhesive left from old carpet padding.
This turned out to be an expensive mistake on my part and don't want it to happen again!

Thank you for all your help!

 

[highup]

If the foam is gone and there are some adhesive remnants they're okay as long as they're not tacky or sticky at all.
Have you checked the floor to see how flat it is? It's rare to see a floor that's within the manufacturer's tolerances. If there's any leveling or filling to be done or if you have any doubts at all about the tackiness of the floor adhesive, then after filling the floor you could skim coat the floor with a thin coat of filler using a flat steel trowel. Back when that foam was put down most of the adhesives dried hard, not tacky but I thought I'd bring that up anyway.

 

[Floorist]

If there are a few sticky spots that you can't get off, sprinkle baby powder or corn starch on them.