SURFACE PREPARATION · ICRI GUIDELINE NO. 310.2R · 9 MIN READ
HOW TO DIAMOND GRIND CONCRETE TO ICRI CSP 2–3: TOOLING SELECTION, MOHS HARDNESS & DUST CONTROL
Over 90% of resinous floor failures trace back to inadequate mechanical surface preparation. High-solids epoxy and moisture vapor barriers do not bond by chemical magic alone—they rely on micro-mechanical interlocking inside opened concrete capillary pores at an ICRI Concrete Surface Profile of CSP 2 to CSP 3.
01 / WHY ACID ETCHING FAILS ON MODERN POWER-TROWELED SLABS
Box-store kits include packets of citric or muriatic acid. On dense, steel-troweled residential garage slabs:
- Zero Laitance Removal: Acid cannot cut through acrylic curing compounds, tire polymer transfer, silicone drips, or hard-troweled cream.
- Entrapped Moisture & Salts: Washing acid off forces gallons of water deep into the concrete matrix and leaves unreacted calcium chloride salts that trigger osmotic blistering under 100% solids coatings.
02 / THE OPPOSITES RULE: MATCHING DIAMOND BOND TO CONCRETE MOHS HARDNESS
Choosing the wrong metal-bond diamond segment either glazes over without cutting (burning a whole day) or wears out a $400 set of diamonds in 400 sq ft. Always follow the Opposites Rule:
| Concrete Hardness (Mohs Scale) | Required Diamond Matrix Bond | Recommended Grit for CSP 2–3 |
|---|---|---|
| Hard / Power-Troweled (Mohs 7–8) | Soft Metal Bond (wears faster to expose fresh diamonds) | 16/20 or 25/30 Grit (Double Segment) |
| Medium Residential Garage (Mohs 5–6) | Medium Metal Bond (standard universal) | 30/40 Grit Metal Bond |
| Soft / Sandy / Abrasive (Mohs 2–4) | Hard Metal Bond (resists premature segment wear) | 30/40 or 40/50 Grit Metal Bond |
03 / 4-STEP FIELD EXECUTION FOR A FLAWLESS CSP 2–3 PROFILE
- Cut the Perimeter & Stem Walls First: Run a 7" hand grinder with a vacuum shroud and 30-grit turbo cup wheel around all perimeter edges, bollards, and garage door tracks before wheeling in the planetary machine.
- Cross-Hatch Planetary Grinding: Run your first pass North–South at a steady walking pace, overlap by 25%, and then run a perpendicular East–West pass. Check with a flashlight held low to the floor—zero shiny hard-troweled spots may remain.
- Chase Cracks & Spalls: Open hairline cracks with a diamond V-crack chaser blade, vacuum out all dust, and fill flush with fast-set polyurea or thickened EPOXY 49 (2A:1B) + fumed silica/cabosil.
- HEPA Vacuum & Water-Drop Test: Vacuum the entire slab twice with a brush-head squeegee wand. Place 5 drops of clean water across the floor—each drop must absorb and darken the concrete within 15–30 seconds before priming with PRIMER 49 or MVB 49.