Yes, you can use sandpaper on concrete floors or countertops to repair etch marks, rough spots, hone or polish the surface, or prep for sealing. Make sure the surface remains wet when sanding and periodically remove all debris to keep from burnishing the cement. Diamond pads or discs are the best options, but you can use metal or wood sandpaper. This Manual Marble Polishing Pad Kit is pretty handy for etching repair on concrete.