Impact damage on polished concrete is rarely just a hole. A dropped tool or a hard wheel leaves three things: a crater, a ring of crushed paste around it, and often a hairline crack running from the edge. Repair only the crater and the ring will still show as a dull halo.

Assess the damage

Feature	What it means	Repair
Crater under 5 mm	Paste only	Patch with matched paste, polish level
Crater 5-20 mm	Paste plus aggregate lost	Chip back to sound concrete, fill in layers
Crushed ring	Micro-cracks around impact	Grind the ring out, not just the hole
Crack from edge	Stress path	Route, fill, then polish
Loose area, drummy	Delamination	Cut out to sound bond, full-depth patch

Repair sequence

1. Clean and dry the area. Wet paste will not bond and will show as a dark spot.
2. Chip or grind back to sound concrete, including the crushed ring, with a small diamond cup.
3. Fill in layers with a matched repair material; deep holes go in two pours to limit shrinkage.
4. Overfill slightly, cure fully, then cut back flush with a cup wheel.
5. Hone the patch through the field sequence, starting one grit coarser than the surrounding floor.
6. Blend 200-300 mm beyond the patch and polish to the same gloss, checking under raking light.

Matching the gloss

• Measure the surrounding gloss first, then polish the patch to that number, not to "as shiny as possible".
• Use the same pad and the same machine speed as the original finish.
• If the patch reads lighter, check the aggregate, not the polish; a resin-rich patch reflects differently.
• Seal the patch with the same product and the same number of coats as the field.

When to replace rather than repair

If the impact broke a section of slab or exposed mesh, patching will fail in service. Cut a clean square, dowel or key the edges, and pour a matching repair section. On visible floors, tell the client the honest choice: an invisible repair is possible for cosmetic damage; structural damage is a different price and a different warranty.

Photograph before and after from the same position. Repair quality is judged months later, and the photo is the only record of what was there.