Quick Answer: Remove old glue from concrete with a grinder fitted with a PCD tool or coarse metal-bond cup wheel, working dry with a dust shroud. Grind in overlapping passes until the glue is gone, then make one light pass with a regular cup wheel to clean the surface for coating.

Choose the Right Tool for the Glue

Thick adhesive and mastic gum up ordinary cup wheels quickly. PCD (polycrystalline diamond) tooling is designed to shave coatings and adhesives without loading, which makes it the fastest option for carpet glue, tile mastic, and epoxy residue. For thin glue films, a coarse metal-bond cup wheel works.

If you already use a machine, fit the PCD tooling for floor removal to grind glue off without constant clogging.

Grinding Technique

1. Scrape any loose glue or carpet remnants with a floor scraper first.
2. Grind in straight, overlapping passes, moving at a steady walking pace.
3. Check the floor frequently: glue hides in low spots and around patches.
4. Follow with a fine pass using a standard cup wheel to clean the residue.

Do not press hard. PCD and cup wheels remove glue with the disc weight and rotation; pressure only heats the adhesive and makes it smear.

Wet or Dry?

Dry grinding with a vacuum shroud is the standard for glue removal, because water turns adhesive into a slippery slurry and spreads it into the pores. If you must grind wet, flush the floor thoroughly and neutralize any residue before recoating.

Dry dust is hazardous silica, so the shroud and a HEPA vacuum are mandatory, not optional.

After the Glue Is Gone

Grinding glue leaves a roughened profile, which is actually ideal for coatings and overlays. Vacuum the dust, wipe with a damp cloth, and check for remaining shiny patches. Glossy spots mean adhesive is still in the pores: regrind those areas before sealing.

FAQ

Can I remove tile glue from concrete with an angle grinder?

Yes, with a PCD or coarse cup wheel. Work in light passes and let the tooling cut; mastic melts and clogs when you push hard.

What is the fastest way to remove carpet glue from concrete?

A PCD-equipped grinder removes carpet glue the fastest. Floor scrapers handle the loose bulk, then PCD cleans the residue.

Do I need to grind all the glue off before epoxy?

Yes. Epoxy needs a clean, porous profile; any remaining glue will peel under the coating.

Conclusion

Match the tool to the adhesive: PCD for heavy mastic and glue, coarse metal bond for thin films, and always dry with a vacuum. The right PCD cup wheel turns the messiest glue job into a quick, coating-ready floor.