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Grind the repair area to a CSP 4-5 profile (open coarse aggregate) for epoxy mortar repairs. Use aggressive metal-bond trapezoid discs such as 4-segment metal-bond shoes or PCD tooling if old coatings are present, bevel the edges of the repair pocket at 45 degrees, and vacuum until white glove clean. Epoxy mortar bonds mechanically to open concrete - a smooth ground surface will delaminate. Do not solvent-wipe after grinding; the epoxy needs a dry, rough, dust-free surface.
Epoxy mortar is a 2-20 mm thick repair product. It does not chemically bond to concrete; it mechanically keys into the pores. A light grind leaves a CSP 2 profile that looks clean but has no texture. Within months, traffic and vibration break the bond. The International Concrete Repair Index calls for CSP 4 for epoxy mortars thicker than 6 mm.
Cut the repair perimeter square with a diamond saw to 10 mm beyond the delaminated area. Grind out loose concrete until it rings solid. Bevel the edges to 45 degrees over 20-30 mm so the epoxy has a key. Grind the bottom of the pocket to open the pores. Vacuum with Hepa, then blow compressed air through the cracks, then vacuum again. Apply epoxy primer within 2 hours.
| Repair thickness | CSP target | Tooling |
|---|---|---|
| 3-6 mm | CSP 3 | 30/40 metal |
| 6-20 mm | CSP 4 | 16/20 metal |
| > 20 mm | CSP 4-5 | 16/20 + bush hammer |
For bottom-of-pocket work, a walk-behind grinder with hard-bond trapezoid discs opens the surface fast. For edge beveling inside the pocket, use a 5-inch angle grinder with a double-row cup wheel - it cuts the 45-degree bevel cleanly. If old epoxy is still on the repair area, strip it first with a PCD cup wheel before you start profiling.
For very tight pockets where the walk-behind cannot reach, use an angle grinder with a bush hammer plate to create a CSP 5 texture that epoxy grips aggressively.
A: No. Acid etching is not recommended for epoxy repairs - it leaves salts and an uneven profile. Diamond grinding is the only accepted method for structural epoxy bonds.
Rough enough that you can feel aggregate with a fingernail. If it looks like fine sandpaper, it is not rough enough.
Prime within 2 hours, then pour within the primer open time (usually 1-4 hours). Grinding and priming must happen same day.
Yes. Sharp 90-degree corners are stress risers - epoxy cracks out of them within a year. Bevel at 45 degrees for a gradual transition.
Epoxy mortar lives on mechanical bond - grind to CSP 4, bevel edges, vacuum white-glove clean, and prime same day. Aggressive metal-bond shoes and PCD stripping tooling make the prep fast. JOY TECH supplies the trapezoid discs and cup wheels used for epoxy repair prep; send us your repair size for a prep kit.
Written and reviewed by JOY TECH - an SGS & BV audited, CE/RoHS certified diamond tools manufacturer founded in 2004, exporting to 50+ countries.
Our factory and quality management system are audited by SGS and Bureau Veritas. Products meet CE/RoHS requirements and every piece is 100% inspected before packing.
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