+1 If the tiles are 9" by 9", the are likely ACM (Asbestos Containing Materials). The tiles themselves are not the real issue because they are not very friable. The Mastic is the issue and caution should be taken when removing that as the previous poster mentioned. As a general rule, if the mastic is black, get it tested at a minimum.

That looks a little like the extra blade they gave to me too. It didn't work well on the tile, but I used it later on the thinset with the speed set low and at a high angle. Every now and then it would break through the concrete top layer so I just did the high spots like you said. I felt like "Ahnold" or Rambo with a Gatling gun. My arms are beat but it is better than what I was facing with the chisel and hammer. I'm ready for the next step now, which is "rest one week" and get stuff on order. You have been a great help. Thanks!

btrflytrvlr, I'm facing the same problem and hence, googled the problem and came across your same question. I'm in So. Fla and I think the humidity hasn't helped the situation. I ripped up my parents carpeting in the bedroom (they don't have a clue yet - I'm hoping after the initial shock they'll be happy) and underneath some of the padding is lightly stuck to the parquet wood flooring. It does seem to come off, but like someone mentioned, it needs some extra elbow grease to get it off - has to be an easier way, I hope. Also, it too has a mirror image of the dots all over the floor. Would love to get them off without maring the finnish. Also, what does one do to fill the small nail holes where the carpet stripping is attached? And, where there are some fine gaps, are these to be filled or just left as is. Seems dust can easily settle in. Hope someone has some tried and true remedies. THANKS!

You could always grind the surface down (the ENTIRE lot). The prints are now 'in' the concrete. I'm guessing the weight of the foot/body caused a slight change in the SURFACE of the concrete. This would have shifted the direction of the surface aggregate to have a different look. Kinda like vacuum lines in a carpet. The direction change of the pile changes the appearance of the carpet. When finishing concrete the pros sweep it or 'brush it' to give it a specific look. I'm guessing your body weight disturbed this brushing enough to cause a visual change. Technically there is nothing wrong with the concrete...but it is an eyesore.