Removing black asphalt/tar-like floor adhesive off concrete effectively

[Shawn Prentice]

I haven't tried anything yet as I haven't started the job. Just doing some pre-job homework since I haven't dealt with this before. I will need to set tile on the concrete when it's stripped, so the adhesive needs to come off completely. Best methods to achieve this or should I be subbing this out. Then if subbed out, who does that type of work typically? Thanks for the help.

Add: Does "cutback" sound right? Mid 1960's house. I have heard some modifieds can go over that. Has anyone done that before?

[rustyjames]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

Just a heads up--that adhesive could contain asbestos.

[Shawn Prentice]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

Thanks, I am aware of that. I know wet scraping is a good method, but I'm not sure about the best solvent to use.

[philthegreek]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

Shawn, I ran into this last year. I started with solvents, but the asphalt adesive had penetrated the concrete. The solvents used are really nasty stuff. One of my local tile distributors suggested a intermediate membrane that was peel and stick. My only alternative would have been to chip the entire surface and pour leveling compound, which would have blown the budget for the 8'x12' kitchen. I mentioned this on the tile forum and was chastised for it. Anyway, 1 year later and still no problems with the install. Just have to make sure the the asphalt is really clean, so some solvent will have to be used to get a surface ready to bond to. I'll have to dig up the product name though.

phil

[Shawn Prentice]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

Thanks Phil. I did a bit of skimming at JB forums and saw the use of self-level with a crack membrane over it, but no clear consensus. Then I saw some mention of razor scraping it and using a modified that is compatible, I think Laticrete makes one for going over cutback. Not finding the cut and dry info so far, but I will dig deeper into JB forum tomorrow.

[Greg Di]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

You would think that SOME company would develop a product that would bond right over the adhesive. It's not like it's not an uncommon situation. I would go so far as to say it's a very COMMON situation.

We can put men on the moon, but we can't bond over that black crap? Hard to believe.

[Shawn Prentice]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

Greg, from additional research I've done since the first post, it looks like there are some modifieds that can be used over it after razor scraping. Just looking for input from the ones I trust, here on these forums, for any experience.

On a completely off the topic issue, I hope there are no negative feelings from the "other" thread as I do appreciate and understand your point of view. And I do respect your knowledge and contributions.

[always-learning]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

Add: Does "cutback" sound right? Mid 1960's house. I have heard some modifieds can go over that. Has anyone done that before?

I've installed tile over cutback adhesive. I've used Mapei's adhesives primarily, over the last 10 years, and , in all honesty, I've yet to have a callback on anything I've installed, other than damage caused by the homeowner, If you really are concerned over the dryset not sticking to the cutback, once you're done cleaning the surface, then you can apply Mapei's primer called Primer WE. Basically, I've just scraped the surface, using basic scraping tools, then cleaned the surface using TSP, allowing it to dry, and then installing tile using Mapei's best thinset

From the manufacturer:

Primer WE is a two-component, polymer-modified, solvent-free water-based epoxy primer for enhanced adhesion to nonporous substrates prior to the application of MAPEI self-leveling materials. When mixed, Primer WE is purple for easy identification. It improves adhesion over smooth, nonabsorbent and difficult-to-bond-to substrates such as properly prepared ceramic tile, cement-based terrazzo, old cutback adhesive residue and approved plywood subfloors.


Here is an informative link for preparation regarding cutback surfaces.

http://www.rfci.com/files/pdf/RFCIRecommended9-04.pdf



http://www.mapei.us/

[dgbldr]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

Shawn, that is indeed cutback, used to glue the old VCT tile. If you want to remove it, you can do so quite well with 747.

There are a number of thinsets that expressly allow installation over cutback. They work fine. I have tile installed over cutback in my own basement, large tile, over 10 yrs ago, no issues ever.

[Shawn Prentice]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

Thanks for the info Chuck and DG.

[Wngsprnt50]

Re: Removing black asphalt/tar-like floor adhesive off concrete effectively

We have numerous apartment complexes that have the asphalt cutback adhesive. Its really not too big of a deal. There are several types of adhesive that will work over it. Also, someone mentioned asbestos. In addition to the adhesive, most likely the tile will also have it if it is a older vinyl type tile.