1. Let it cure and dry
New concrete needs time to cure and lose excess water. Coating manufacturers commonly ask for a minimum cure period and set limits on slab moisture. Test with in-situ RH probes (ASTM F2170) and/or calcium chloride (ASTM F1869) rather than relying on age alone.
2. Remove contaminants
Oil, grease, curing compounds, sealers, old coatings and efflorescence all block adhesion. Degrease first, then remove film-forming contaminants mechanically. Test suspect areas with a water-drop test: water that beads instead of darkening the concrete points to a sealer or contaminant.
3. Remove laitance and create a profile
Laitance is the weak, cement-rich skin on the slab surface. Mechanical methods remove it and leave a profile matched to the coating, referenced to ICRI CSP chips:
| Method | Typical CSP | Best for |
|---|---|---|
| Diamond grinding | 1–3 | Thin coatings, sealers, polished floors |
| Shotblasting | 3–6 (adjustable) | Most high-build coatings and polyurea |
| Scarifying | 4–9 | Removing thick coatings, overlays |
| Abrasive blasting | 3–7 | Walls, columns, irregular areas |
4. Repair and detail
Fill cracks, spalls and bugholes with compatible repair materials. Treat moving joints and cracks with flexible details, and saw-cut termination keys at edges, drains and doorways so the coating has a locked-in edge.
5. Clean, prime and verify
- Vacuum thoroughly; dust is a bond breaker.
- Prime to seal pores and reduce outgassing, ideally on a stable or falling slab temperature.
- Verify bond on a test area with pull-off testing (ASTM D7234) before full production on critical jobs.