Quick Answer

Yes, you can diamond-grind and polish a floor that was already scarified or shotblasted, but you cannot jump straight to 120 grit. Scarifiers leave sharp, jagged chatter ridges that read CSP 8-9; shotblasting leaves a rounded, pebbled texture at CSP 4-5. Both need a fresh metal-bond grind starting at 30 or 40 grit to flatten the peaks before you move through the resin sequence. Expect two to three extra passes per grit and 15-25% higher tool wear than on a smooth troweled slab.

What the Previous Mechanical Prep Leaves Behind

• Scarified (flail machine) - deep, parallel teeth marks, exposed aggregate, loose sand in the valleys, and a profile that feels like coarse sandpaper. Typical CSP 8-9.
• Shotblasted - uniform, rounded dimples, no loose aggregate unless the slab was soft. Typical CSP 4-5.
• Scarifier plus shotblast combo - the worst case: deep teeth marks with rounded pebbles inside the grooves. This needs the longest flattening pass.

Run your hand across the floor. If your palm catches on ridges, you are not ready for resin pads yet.

Starting Grit and Bond Selection

On a scarified floor, start at 30 grit metal bond with a soft-to-medium bond on normal concrete; on hard concrete (Mohs 5+), use a medium to hard bond to avoid premature glazing. On a shotblasted floor, you can start at 60 grit because the profile is already mild. Skipping the first grit leaves chatter marks that show through every later step.

For the first flattening pass, our Diamond Trapezoid Grinding Disc (JOY-TP-R3) with triple round segments gives aggressive, chatter-free cutting on planetary grinders.

Sequence: What to Run and How Long

Stage	Scarified floor	Shotblasted floor
Metal bond	30, 60, 120	60, 120
Cross-passes per grit	3	1-2
Densifier	After 120	After 120
Resin sequence	200, 400, 800, 1500	200, 400, 800, 1500
Tool wear vs normal	+25%	+10%

Common Mistakes on This Kind of Floor

• Starting too fine - 80 or 120 grit cannot flatten 2 mm scarifier teeth; the pads load up and glaze.
• Skipping the vacuum between grits - loose aggregate sand scratches the next pad pass.
• Using a hard bond on scarified soft concrete - glazing happens within 20 m². Ask us about bond recommendation before ordering.
• Forgetting edge prep - scarifier teeth are deeper at the wall; hand-grind edges with a Diamond Cup Wheel (JOY-CW-R6) before the machine reaches the perimeter.

When to Strip Residual Adhesive First

If the scarifying was done to remove glue or VCT, residue remains in the valleys. Run a single PCD pass first. Our PCD Cup Wheel (JOY-CW-PCD6) cleans the glue pockets before you switch back to diamond metal bond.

Frequently Asked Questions

Q: Can I polish directly over shotblasting texture?

A: Not for a high-gloss finish. Shotblasting leaves CSP 4-5 dimples that reflect unevenly. You need at least 60 and 120 grit metal bond passes to close the profile first.

Q: How much does scarifying add to the tooling budget?

A: About 15-25% more metal-bond plates than a troweled slab, because the jagged texture abrades diamonds faster. Resin pad life is about the same.

Q: Will scarifier marks disappear at 400 grit?

A: Only if you fully removed them at 60 and 120. If ridges remain, they show through every later grit and look like rakes in the finished floor.

Q: Is a scarified floor OK to seal without polishing?

A: Yes. Sealer will lock in the texture and give you a CSP 8 non-slip industrial floor, but do not expect gloss.

Conclusion

A scarified or shotblasted floor is recoverable - it just needs one extra grit at the start and a slightly harder bond to chew through the mechanical texture. Match the starting grit to the CSP you are looking at, vacuum between passes, and the rest of the polishing sequence runs normally. Contact JOY TECH for a bond recommendation matched to your concrete hardness.