Quick Answer

To cut concrete with an angle grinder, fit a dry-rated diamond blade matched to your grinder's size, mark the line, make several shallow passes instead of one deep cut, and let the blade do the work at full speed. An angle grinder cuts concrete up to about 50mm deep in one pass on edges and up to 30mm on flat work. For anything deeper, cut both sides and break the core, or use a proper saw. A 125mm or 230mm grinder with a quality diamond blade handles most small concrete jobs. For the right tooling on this job, see general purpose diamond blades, stone and masonry blades.

Choose the Right Blade and Grinder

Use a diamond blade rated for dry cutting of concrete, sized to the grinder guard: 100mm, 125mm or 230mm. The blade must state it is for masonry or concrete; a metal-cutting blade will fail. Check the blade speed rating against your grinder's RPM, and never use a blade larger than the guard allows. For dust control, fit a cutting shroud and connect a vacuum, because concrete dust is a silica hazard.

Set Up Safely

Clear the work area, mark the cut line with chalk, and clamp or wedge the workpiece so it cannot move. Wear eye protection, a dust mask or respirator, hearing protection and gloves. Stand clear of the line of rotation in case the blade binds. If you are cutting a slab or paver, support both sides of the cut so the piece does not drop and pinch the blade.

Cutting Technique

• Run the grinder up to full speed before touching the concrete.
• Guide the blade along the line with light forward pressure; do not force or twist it.
• Make a first shallow pass of 5 to 10mm, then deepen in steps until you reach the full depth.
• On thick pieces, cut both faces and use the remaining web as a break line instead of forcing one deep cut.
• Lift the grinder clear when finished and let the blade spin down before setting it down.

Common Mistakes to Avoid

The two most common mistakes are cutting too deep in one pass, which overheats the blade and causes kickback, and using a glazed or wrong blade, which smokes and stalls. Cutting at low speed also burns segments. If the blade stops cutting, dress it on an abrasive block rather than forcing it. Stop immediately if the grinder vibrates or the blade wobbles; that means a damaged blade or spindle.

Frequently Asked Questions

Q: How deep can a 125mm angle grinder cut concrete?

A: A 125mm grinder reaches about 35 to 40mm depth, which is enough for chasing, cutting thin slabs and cutting blocks. A 230mm grinder reaches about 65 to 70mm.

Q: Can I cut concrete with a cutting disc for metal?

A: No. Metal cutting discs are not designed for concrete and will wear out instantly or shatter. Use a diamond blade rated for masonry and concrete.

Q: Why does my blade smoke when cutting concrete?

A: The blade is glazed, the cut is too deep, or you are forcing the grinder. Slow the feed, make shallower passes, and dress the blade if it has stopped cutting.

Conclusion

An angle grinder with a dry-rated diamond blade is the practical tool for cutting concrete on small jobs. Match the blade to the grinder, work in shallow passes at full speed, and control the dust. Follow that routine and you will get clean cuts without burning blades or risking kickback.