I pulled up some old tiles from the basement floor several months ago. Now I decided to remove most of the rest of them and found out recently that the black mastik glue probably contains asbestos. I would like to install new self stick vinyl tiles over the floor. My questions are: Will the new tiles stick to the floor considering the old mastik is still there? Do I need to seal the cement floor first? The box of tile recommended sealing so I bought some bottles of bond enhancer for cement floors. It is supposed to be put on with a paint roller. Is it necessary to use or even safe considering the asbestos mastik on the floor now? The house was built in 1946 and the tiles were covered w wall to wall when I had it inspected before buying it. Replacing the carpeting is not an option due to my cats urinating on the carpet. I put a treadmill in the basement on top of a small area rug which is on top of the black mastik. Is it safe to go down there and use it or should I cover the black mastik before doing anything down there? Any help would be greatly appreciated.

Are you positive that the mastic contains asbestos? Maybe it is a good idea to have an asbestos removal professional test it and find out how much of a health hazard you are dealing with.
I urge you to do that

I believe that answer will determine what you can and need to do about the place, and make an informed decision. I can't, just based on your explanation, tell you what is or is not safe.

Thanks for your advice.

No I am not certain that it contains asbestos. I was just going based on what the project manager from work thought, as he supervises renovations. Also based on many descriptions on the internet. I don't think I can afford to bring in a professional to test it though, so I may have to try another method. Perhaps self test kit from Home Depot, I think there is such a thing but haven't actually looked for one yet.