Quick Answer

Concrete grinding discs use a metal or hybrid bond with coarser diamond grit to cut hard, dense concrete, while masonry discs use a softer bond suited to brick, block, and mortar. Using a masonry disc on concrete glazes quickly; using a concrete disc on soft masonry grinds too aggressively and leaves deep gouges.

What the Bond Controls

The bond is the metal or resin matrix that holds the diamond grit. Hard concrete needs a bond that wears just fast enough to expose fresh diamonds; a masonry disc's bond is softer, so on concrete it wears away without cutting and the diamonds polish smooth. The grit size matters too: coarse grit (16-30) removes concrete fast, fine grit (80-200) smooths.

Concrete Discs: What They're Made For

Choose a diamond grinding disc for concrete when the material is cured concrete, screed, or concrete with aggregate: slabs, floors, patios, and repairs. Metal bond discs level high spots and remove coatings; hybrid bond discs are a versatile middle option for general concrete work on a hand grinder or floor machine.

Masonry Discs: What They're Made For

Masonry discs suit soft, abrasive materials: clay brick, concrete block, mortar joints, and softer stone. The softer bond wears fast and continuously exposes fresh diamonds, which is exactly what soft materials need. They are also a common choice for grinding down mortar on repointing jobs and for cleaning brick faces.

How to Tell Which Disc You Have

Check the label: discs marked for concrete, screed, or granite are hard-bond tools; discs marked for brick, block, or masonry are soft-bond tools. If the disc has no label, compare segment hardness with a thumbnail: masonry segments often feel softer and erode visibly during work. When in doubt, start with a concrete disc and a coarse grit.

Frequently Asked Questions

Q: Can I use one disc for both concrete and brick?

A: A hybrid bond disc can handle both on light work, but you will get better results using a dedicated disc for each material, especially on heavier jobs.

Q: Why did my masonry disc stop cutting concrete?

A> The soft bond glazed over against hard concrete. Recondition it on an abrasive block and switch to a concrete-rated disc.

Q: What grit should I use to smooth concrete after grinding?

A: Step up from coarse to medium: 40-80 grit smooths, 120-200 prepares the surface for polishing or coating.

Conclusion

Match the disc bond to the material and the job goes fast; mismatch it and the disc glazes or gouges. Keep a concrete disc and a masonry disc in your kit and reach for the right one: hard bond for concrete, soft bond for brick and block.