Concrete Crack Repair Before Grinding Workflow

Steps

1. 1

   Crack Assessment

   Identify crack type: hairline (<1mm), medium (1-5mm), or structural (>5mm). Determine if crack is active (still moving) or dormant. Check depth with wire probe.

   Hairline: Cosmetic only, may not need filling\nMedium: Fill required before grinding\nStructural: Engineer assessment needed, do not grind over

2. 2

   Crack Preparation

   Chase crack with angle grinder and crack-chasing blade to create V-groove (wider at top). Vacuum all dust and debris. Blow out with compressed air.

   Pro tip: V-groove gives filler more surface area to bond. A flat crack will pop out under grinding pressure.

3. 3

   Filler Selection

   Choose filler based on crack width and floor use. Polyurea for fast cure (15 min). Epoxy for structural strength. Polyurethane for flexible/active cracks.

   Polyurea: Fast cure, semi-flexible, good for most grinding prep\nEpoxy: Strongest, rigid, best for structural\nPolyurethane: Flexible, for active cracks\nSand-filled epoxy: For wide cracks >5mm

4. 4

   Fill Application

   Mix filler per manufacturer instructions. Pour into crack slightly overfilled (will be ground flush). For deep cracks, fill in layers.

5. 5

   Curing

   Allow full cure before grinding. Polyurea: 15-30 minutes. Epoxy: 4-24 hours depending on product. Do not grind uncured filler.

   Pro tip: Test cure by pressing thumbnail into filler. If it dents, its not ready.

6. 6

   Grind Flush

   Once cured, grind filler flush with surrounding concrete using 40-60 grit metal bonds. The filler should blend seamlessly with the floor.

Tools Required