Removing old adhesive from concrete

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hayley3

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To keep water out of the garage, a contractor glued down a threshold at the entrance. I need to replace the threshold but I cannot get up the old adhesive. Was hoping someone might know of a solution. I tried flooring adhesive remover but it didn't work. I was not sure where to post the question.

Thanks,
Cheryl
 

jadnashua

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IF it's really stuck, you may just be able to glue a new one on top of it.

FWIW, some of those adhesive removers can leave a residue that gets absorbed into the concrete that can prevent new stuff from creating a good bond. Sometimes, you end up needing to literally grind it off.

You might try to pick up a floor scraper. This is essentially an oversized razor blade on a long handle so you don't have to bend over. The blades dull quickly but it doesn't sound like you have a lot of area. Some boiling water and the scraper may get most of it up. The hot water will soften it, making scraping more efficient.
 

hayley3

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IF it's really stuck, you may just be able to glue a new one on top of it.

FWIW, some of those adhesive removers can leave a residue that gets absorbed into the concrete that can prevent new stuff from creating a good bond. Sometimes, you end up needing to literally grind it off.

You might try to pick up a floor scraper. This is essentially an oversized razor blade on a long handle so you don't have to bend over. The blades dull quickly but it doesn't sound like you have a lot of area. Some boiling water and the scraper may get most of it up. The hot water will soften it, making scraping more efficient.


Oh wow, I never thought of that.... but I did notice that remover absorbs really good into the concrete and was worried it would discolor it. If it had stayed on the surface it might've worked better. I did buy a huge scraper with a blade from Harbor Freight, (which is in transit) but this stuff is really hard. For the rubber threshold to stick, it can't have anything on the floor. I have an orbital sander but I doubt that would work on it. Some of it is glue but some of it is hard, so it's like he used two things to get it to stick and I can't remember who did it.
 

hayley3

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Awwww where did that link go about the grinding wheels? I decided I will go ahead and buy an angle grinder.
 
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jadnashua

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A diamond cup wheel. Ideally, your grinder would have a dust collector. It will be VERY dusty...wear good eye and dust protection, and keep the area blocked off so you don't get it everywhere.

If it were a larger area, you'd probably want to rent a scarcifier machine.
 

hayley3

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My grinder specifically says "Never use a cup wheel". I wonder why that is.
Also I tried my Bosch oscillating multi-tool with a grinding blade attachment and it works (although painfully slow) to get the top hard stuff off but leaves a pliable residue beneath that. However, although the scraper attachment worked, it's too slow so I felt I needed a better tool, so yesterday I ordered some Zec Silicon Carbide Discs which are supposed to work for removing sealants on concrete.
 

bcarlson78248

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When I was trying to remove adhesive under old VAT I found this product that got a lot of good reviews, but I never actually used it. https://products.franmar.com/products/mastic-adhesive-remover-for-concrete-bean-e-doo Its not petroleum based , so its not supposed to infuse anything into the concrete that would cause problems later with new flooring.

My tile adhesive showed positive for asbestos, so I ended up hiring an abatement company to remove both tile and adhesive. I don't know what they used in their machine (it was liquid), but the final result was a smooth, clean floor that could be painted or stained almost immediately.

Bruce
 

cacher_chick

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If the adhesive is really hard, seeing how it is such a small area, I would first scrape with a carbide blade paint scraper, and then try sanding off the remainder with an orbital sander with 60 or 80 grit discs. If the adhesive is hard, the sander will reduce it to a powder.
 

hayley3

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When I was trying to remove adhesive under old VAT I found this product that got a lot of good reviews, but I never actually used it. https://products.franmar.com/products/mastic-adhesive-remover-for-concrete-bean-e-doo Its not petroleum based , so its not supposed to infuse anything into the concrete that would cause problems later with new flooring.

My tile adhesive showed positive for asbestos, so I ended up hiring an abatement company to remove both tile and adhesive. I don't know what they used in their machine (it was liquid), but the final result was a smooth, clean floor that could be painted or stained almost immediately.

Bruce

Thanks, I read the reviews online, it sounds like great stuff.
 

hayley3

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If the adhesive is really hard, seeing how it is such a small area, I would first scrape with a carbide blade paint scraper, and then try sanding off the remainder with an orbital sander with 60 or 80 grit discs. If the adhesive is hard, the sander will reduce it to a powder.
I wish I knew which adhesive they used. When I am able to scrape off the hard top layer, the remaining layer is white and putty-like, so it's like caulk but it's not easy to scrape. I bought this thing from Harbor Freight and so far it does the best job but it's not easy. Right now it's wet from the heavy rainfall so that may have softened it some. It would be easier to scrape if it were brittle which it is not.
 

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AlexWilliams

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I'm glad I found this post because for the last week I've been trying to remove the adhesive from the threshold in the garage. I tried with boiling water and a scraper but I couldn't remove all of it. I even tried my orbital sander with dust bag but some of the adhesive it's still there. I may end up hiring an abatement company because this is taking too much time, but I'm looking for solutions here, maybe I'll find something to work. I think the orbital sander didn't work because the adhesive was softened by the boiling water and I may try that again. However, I'm looking forward to any advice.
 
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