The mortar used to install ceramic tiles creates a fast and strong bond between the tiles and the installation surface. Once dry, the mortar turns into a material that's as hard as concrete. Removing this mortar after removing the tiles can be a labour intensive, messy process. When the mortar cannot be removed using chemicals, you'll actually have to grind away the material until you reach the concrete beneath. Depending on the size of the area, this could take hours, producing dust that can cover the surrounding area. Once completed, however the concrete will be clear of any traces of the mortar, and prepared for any resurfacing you may wish to do.
Cover every surface of the room with dust sheets, except for the area containing the mortar to be removed. Tape the cloths down using masking tape.
Wear the dust mask and safety goggles to protect your eyes and lungs from the dust that will be released by the removal process.
Place an aluminum oxide grinding disc onto the concrete grinder. Plug in the grinder and move it to the edge of the mortar bed. Large electric floor grinders can be rented at home improvement stores or equipment rental shops. Connect the vacuum tube from your concrete grinder to a canister vacuum cleaner.
Spray down the surface of the mortar with water to cut down on the dust created when grinding the mortar. Turn on the vacuum cleaner to collect the dust created from the grinder.
Turn on the grinder and run it over the surface of the mortar using a small circular motion. Keep the grinder moving constantly and watch for the concrete surface beneath the mortar. Avoid remaining in one place for any length of time to prevent grinding down into the concrete below.
Use multiple passes to remove the mortar. On the first pass, level the surface, removing any sharp protrusions. Use the second pass to remove the majority of the mortar, leaving only the hardest remnants on the surface of the concrete. On the third pass, remove these hard remnants, reducing all the mortar to dust.
Turn off the grinder after each pass and sweep up any mortar dust that the vacuum missed to better see your progress. Wet the surface of the mortar again after each sweeping to help with dust containment.
Remove any debris and dust after finishing the grinding process, and then remove the dust sheets. Clean the surface of the floor, first sweeping and then washing away any mortar dust that may be left on the concrete.