# Removing Glue/Mastic from Concrete



## Klawman (Nov 10, 2009)

I am removing an engineered hardwood floor from concrete. The wood removal is going fairly well, but the problem is the material used to bond the wood to the concrete slab. Whether it is mastic or wood glue I don't know. It will come off with a wood chisel and hammer, but that will take forever and a week.

If this was a larger area I think I know what to do (rent a floor buffer and a full size diamabrush pad), but it is only approximately 175 square feet. I am thinking of buying a 4.5" diamabrush wheel to use with a neighbors angle grinder. HD also has other machines to consider.

This is the small wheel for use with an angel grinder.









Here is a pic of the "adhesive" to be removed. I am not very sure what it is, but its 24 years old.



Do you have any suggestons other than where a dust mask and next time pay someone to do it.


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## JourneymanBrian (Apr 1, 2015)

If it's oil or solvent based you can use stripper on it


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## rusty baker (Feb 13, 2009)

JourneymanBrian said:


> If it's oil or solvent based you can use stripper on it


That depends on what the next flooring will be.


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## Klawman (Nov 10, 2009)

We are trying to decide if the next floor will be porcelain tile or engineered hardwood.

So far, it seems to do little good to wet the stuff with water. It just makes it slightly pliable as opposed to hard.

What types of stripper will make it difficult for what kind of adhesive to bond?


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## oh'mike (Sep 18, 2009)

Do NOT use a chemical stripper---that stuff will soak into the concrete and cause the next floor to not stick-(bond breaker, Rusty knows his floor prep)

A chipping hammer with a sharp blade might work for you--they can be rented--keeping the blade sharp is another issue---


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## JourneymanBrian (Apr 1, 2015)

If you remove the stripper residue what should be the problem?


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## Colbyt (Jan 27, 2014)

After scraping as much as possible with a stand up floor scraper, I used a wire cup brush. I can't say it was fun but it worked.

The carbide wheel can and will grind the concrete.


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## rusty baker (Feb 13, 2009)

JourneymanBrian said:


> If you remove the stripper residue what should be the problem?


It soaks into the concrete. No way to get it out.


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## Klawman (Nov 10, 2009)

Thanks all. This is a classic example of the importance of knowing what NOT to do; using chemical agents which is what the guys at the local Home Depot wanted to sell me.

I am not sure what O'Mike means by a chipping hammer. There are several sizes of reciprocating hammers I can rent and I was considering the smallest; a Makita 11 pound. The cost of rental fits but then it is nearly an additional $40 to rent the scraper bit. As for the wood, I have almost gotten it all off with the pictured sledge and wrecking bar.

I tried my corded sawzall with Milwaukee spyder blades and they snapped really quick.

Just to test this stuff, I ran an orbital palm sander over it with 40 grit paper and it will come off, but with months of sanding. The scraper on my Demel Multimax will do the job, but would probable take a month and a lot of blades.

Has anyone ever used a diamabrush like the one pictured in post 1. I don't think that is the same thing as a carbide wheel.

The area only measures 150 square feet.

To put this into context, there will be another 1,000 square feet refloored, which is covered with either carpet, tile, or marble, plus a ton of furniture to move. That is too much for me to tackle and I am wondering if I should leave the adhesive removal in the kitchen to them, since they should already have the same equipment on site for removing thin set and padding glue.


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## oh'mike (Sep 18, 2009)

Rental stores will have power floor scrapers---equiped with replaceable razor scraper blades---stand up and push --noisy but easier on the back than a chipping hammer (Google 'Bosch Bulldog' to see what a small chipping hammer looks like)


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## Klawman (Nov 10, 2009)

oh'mike said:


> Rental stores will have power floor scrapers---equiped with replaceable razor scraper blades---stand up and push --noisy but easier on the back than a chipping hammer (Google 'Bosch Bulldog' to see what a small chipping hammer looks like)


Thanks, Mike. I have been looking at the rentals at the HD. One is what I think is Makita's version of the Bosch Bulldog.










Had I known what a ***** this would be, I would have rented one of these (or would it lift up the wood/).







HD also rents a lighter duty version which is this one, which the HD site says Removes carpeting, underpadding and vinyl tiles, glue, parquet, etc.







One advantage of it, if it works, is it weighs a lot less and I don't have a truck to carry it in. 

I wonder how well that will work given that the wood is almost all up. Meanwhile, I contracted for the kitchen remodel, not the flooring as the entire first floor is being done, but the remodeler who isn't really interested in the floor told me that floor demo runs $2 a sq ft around here.

Do you think either of these machines would remove the thin set if I first pop off the tiles in the bathrooms and service room? I don't know what they used to fasten the marble to the entranceway. I am tempted to demo half the first floor one day and, after shifting all the furniture back, to the other side do the other half. It's a lot of work, but after rental equipment costs I should save $2K.


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## Klawman (Nov 10, 2009)

It's hard to have any confidence in the guys at HD. The guys at one HD said I could use either of the power scrapers depicted in my post just above, then the one at another HD said they wouldn't work and were only for removing vinyl.

I hate renting and may buy this "1-1/8 in. 10 Amp Heavy Duty SDS Variable Speed Rotary Hammer at Harbor Freight", which just opened a store in my area and just across from the HD. I am sure the Bosch Bulldog is better, but this will likely never be used again.










with this 2" scaling chisel.










My plan is to use it to also remove about 200 sq feet of marble and 150 sq feet of tile; both on the concrete slab. There is also about 800 sq feet of carpeting to remove, but I have tested some spots and the adhesive securing the pad was used very sparingly.


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## oh'mike (Sep 18, 2009)

I own a Harbor Freight Rotory Hammer----I bought it about two years ago for a one time use----works just fine---I've used it and loaned it out--that thing paid for itself and just keeps making me money.


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## Klawman (Nov 10, 2009)

Thanks, Oh'Mike. It sounds like for the cost of the hammer and bit, around $90, it is worth a try. I can then tear up the rest of the ground floor room by room, will save at least $60 on tool costs and will own the equipment when the job is done.

As for the fancy diamabrush wheel, I found another Marine working at the HD tool rental and, after looking at a sample floor board I brought with me, he thought the adhesive would just gum any kind of abrasive up, so it looks like the way to go is a rotary hammer. He also didn't think the power stripper would take this evil stuff off.

Anyhow, it looks like I get to buy another tool and that is always good.


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## oh'mike (Sep 18, 2009)

If you have a way to sharpen that cutter, you will do well to break it out and use it--

he edge will round over after a while--a few moments at the bench grinder and you will have it sharp again---


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## Klawman (Nov 10, 2009)

oh'mike said:


> If you have a way to sharpen that cutter, you will do well to break it out and use it--
> 
> he edge will round over after a while--a few moments at the bench grinder and you will have it sharp again---


Thanks for that tip. I was thinking of also getting a small bench grinder at the HD; something I have wanted a long time.


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## intelpcguy (May 10, 2015)

Have you considered wet grinding the glue off? I use a Hitachi VS 7" sander / polisher ( SP 18V ) with a 7" turbo diamond wheel, and a plastic home made cup to contain the slurry. I use a yellow sponge ( same kind for grouting ) and generously sprinkle the area, and it will remove any and all adhesives, poly modified thinset, what not ) with no dust. Of course from time to time I have to stop to remove the caked on sludge, and go back to grinding. Considering it's not really meant to do grinding duties, it has held up for over 15 years and I have yet to kill it. I used to use a Makita HK1810 power scraper for such duties ( and slightly wet the area to minimize dust ), but it has broken down ( needs a trigger ), and hence my new solution. You can buy a cheap HF 9" grinder, buy a turbo wheel for it, and then buy a dust extraction cup ( tape off the dust ejection port where the vacuum hook up would go ) and you got yourself a wet grinder. Of course this goes with out saying you should be plugged into a GFCI outlet when doing all this.


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## Klawman (Nov 10, 2009)

Thanks, IntelPCGuy. I was wondering about something like that and, in fact, was going to ask about the grinding wheel (I asked about the small diamabrush wheel which is similar but not the same thing and a lot more expensive. 
The size that goes on an angle grinder). I even started to post a picture of one but got distracted. For my purposes it may be a good way to go. Possibly I should go with both a chipping hammer and a grinding wheel, as I can use the hammer for removing tile and marble, as well as perhaps the bulk of the adhesive, albeit mastic or thinset, and then follow up with the grinder. How do you think that wet grinding would work if hooked up to a wet vac? My guess is that the slurry would immediately clog up the filter.


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## Klawman (Nov 10, 2009)

*Sharpening the edge*

Oh'Mike, Trying to keep expenses down but picking up on the importance of keeping an edge on the the scraper/chisel, I was about to buy a bench grinder and then I remembered the old Dremel rotary tool has a grinding stone that I never used. I think for DIY use it may be all I need.


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## Klawman (Nov 10, 2009)

I almost bought a rotary hanmer at HF, but first got a $10 pole scraper to see how it works, if at all. The know it all at HD rental said their massive SDS Max scraper won't even remove this stuff. Guess what, the hand pole scraper will do it, but it is a lot of work. There is a you tube video showing how to cut one, insert a sds bit and make a power scraper for under $20. I think I will give that a go.

One thing about the HF 1-18" sds plus rotary hammer for $78, it is heavy as hell. It is better for what I need than the sds plus rotary hammer, which is $72, but weighs a lot less. Supposedly the hammer function of the light is more likely to fail. I just have to decide what the back can take.

But I was pleasantly surprised at how well the cheap $10 4" pole scraper works.


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## Klawman (Nov 10, 2009)

It is actually working! I bought the heavier than hell Harbor Freight SDS plus rotary hammer, see the picture, and modifying a youtube video I put together my SDS 4" scraper for $25 ($16 if you don't count the cost of the other 4 drill bits I had to buy to get a cheap set of SDS bits).

The scraping pictured took about 2 hours. I only wish I had this beast hammer drill when I was demoing the wood flooring. I am going to get a SDS chisel that should turn the bulk of the wood removal to a 20 minute job instead of 2 hours.

And my back says thank you to everyone.


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## oh'mike (Sep 18, 2009)

Good work---Did you buy the scraper bit at Harbor Freight?


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## Klawman (Nov 10, 2009)

Thanks for the pat on the head, Oh'Mike. Yep. that is a 4" pole scraper purchased from Harbor Freight for $10 during one of their frequent sales. I cut the pole to size with my hacksaw and then ran a 1" SDS bit into it, also purchased at HF as part of a set that ran $16. The trick was the cutters at the lip of the bit. A buddy got them off using a hammer, a carbide wheel, and a portable torch.

Warning, the first one broke. I bounded it into the handle too hard, using the hammer function, and perhaps was too aggressive. This one is going strong.

I found it works best on about 60% speed. I no have it down to where I can clean an 10 foot 4" ribbon in about two minutes. No mess and no chemicals. Not even a dust problem.


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## Klawman (Nov 10, 2009)

oh'mike said:


> Do NOT use a chemical stripper---that stuff will soak into the concrete and cause the next floor to not stick-(bond breaker, Rusty knows his floor prep)
> 
> A chipping hammer with a sharp blade might work for you--they can be rented--keeping the blade sharp is another issue---


This suggestion of oh'mike was also a good one, that I didn't take as I was concerned that with my uncraftsmanlike skills, meaning none, I would catch an edge and damage the concrete. I bought something for removing the 20 some square feet of engineered wood; not just for that but since I intend to use it to remove 300 square feet of 12"marble tiles and porcelain tiles. A sds-plus 1-12" tiling chisel from Lowes. It is still possible to catch an edge on the crete, but you would have to try hard to do it. 

BTW, when using it to pop the wood off the floor, I set it on max power. Still takes some work, but about 1/4 or 1/3 doing it with a hammer and pry bar.

Damn I love power tools.


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## oh'mike (Sep 18, 2009)

I'm glad that tool is working well for you---

I purchaced one for a job,figuring it would be cheaper than renting---
It was paid for by that one job---and sure has come in handy many times since---

I was accustomed to a Hilti---that is one fine tool by cost a big bunch--I just don't use a big hammer drill often enough to justify the expence.


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## Klawman (Nov 10, 2009)

You are right about it paying for itself. If rented, I would have needed it for a full day at a cost of $120. When I do the entrance, that would be another $60. Then $60 for the service porch tile and thin set. I don't know if I will use it for getting carpet pad/glue off. 

Then I plan on building a patio cover and will use it to drill holes in the concrete for anchor bolts. (My wife and I did one when first married 30+ years ago so this is hopefully something I can handle. I am replacing the tiles in the upstairs bath for another $60 rental savings. I may need it to anchor a gun safe to the garage floor. As part of this flooring job, I may also want to remove a pony wall, which is partially built into a 8" cut back into the side of the raised concrete entrance way. Not sure, but if I do I am guessing that I may need to drill holes to anchor/epoxy rebar to tie the additional pore into the slab. (Before drilling the slab, it is being X-rayed to see if it is post stress. I am pretty certain it isn't, but that is needed to know for certain.)

It was a good buy any way you cut it it. Thanks.


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