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How do you fix cracks before spray resin?
Fix cracks by width, and only once they’re dry. Hairline cracks get Step Safe Heavy Duty brushed in, cracks from 2 to 10mm get Shieldcoat Slab Repair, and anything wider gets a cement based fill first with Slab Repair on top.
Steps
- Make sure the crack is dry. Same rule as the slab: dry concrete, at least 28 days old.
- Measure the width and pick the repair from the table.
- Fill it and feather it flush with a flexible putty knife.
- Pressure clean, then prime with Primer X once the repair has gone off.
| Crack width | Repair |
|---|---|
| About 1mm | Step Safe Heavy Duty, brushed in with a small brush |
| 2 to 5mm | Slab Repair |
| 5 to 10mm | Slab Repair in two layers, 1 to 4 hours apart |
| Over 10mm | Cement based repair for the bulk, then a 2 to 5mm layer of Slab Repair |
Why a flexible filler?
Concrete moves. A rigid filler cracks again when it does, and the crack shows straight back through your coating. Slab Repair stays flexible, so the repair lasts as long as the spray resin over it. More on the prep in spray resin driveways.