Found this by doing a search.
" But if you need BARE concrete because you want to stain or paint/epoxy it, you're going to need a concrete floor grinder. A concrete floor grinder uses either carbide cutting bits or carbide abrasive pucks to literally grinds away a thin layer of concrete, along with whatever's stuck to it. It's extremely noisy and dusty, but if you need to take the floor to bare concrete, it's your tool. There are two types. The larger one uses a machine just like the commercial floor buffers you see janitors using, but with a special plate that holds the cutters. For spot work, there's also a smaller one that looks like a router on steroids. If your entire floor is covered with adhesive, you'll need the big buffer model. If you've got the snail trails, either model will work, but the hand-held model will be less messy because you're only grinding a 4" swath instead of the 20" of the bigger model. You may have to call around to find a rental yard that has a floor grinder -- 2 of my 4 local HomeDepot's rent them. "