C04.06
Urethane concrete, patch, and joints
MavCrete and MavGrout are a different sport — 15-minute pot life, keyways, trowel discipline, and a wet edge measured in minutes. Patch and joint products have their own clocks.
- Run a MavCrete placement to the sheet: mix, spread, wet edge, broadcast
- Cut keyways and honor terminations on every cementitious install
- Use the right patch and joint product — and never a rigid filler in a moving joint
Urethane cement family — critical numbers per sheet
| Requirement | Value |
|---|---|
| Pot life (MavCrete UM / MavGrout USP) | 15 minutes @77°F — spread within 3 minutes of mixing |
| Wet edge | Abutting edges within 10 minutes; 'wet edge installation is imperative' on every sheet |
| Temperatures | Ambient/surface 40–85°F · material 50–80°F (guides: 60–80°F) — below 60°F the UPA topcoat must be Fast Cure |
| Concrete | Cured 14 days minimum and 3,500 psi; 300 psi pull-off; broom finish fully removed |
| Profile | MavCrete UM and MavGrout USP: CSP-5 or coarser (40-grit). UF-HD / UM-SL / UQ-HD / UQB systems: CSP 3–5 |
| Keyways | 5/16" x 5/16" minimum at all terminations, joints, columns, doorways, drains |
| Mixer | Proper mortar mixer and paddle (the sheets name the MAN-U-FAB M-61) — complete mix, minimum air |
| Thickness | UM: 1/4"–3/8" trowel. UF-HD / UM-SL: 3/16" + broadcast = 1/4". UQ-HD: 1/8" + broadcast = 3/16". USP sloping: 1/2"–3" |
| Trowel discipline | Finish strokes one direction, do not overwork the mortar, no more than two light passes with the mohair roller |
| Broadcast | To rejection on the wet slurry — never onto the wet edge until it is settled and back-rolled |
| Cure to traffic | UM: light 6 hr, full 24 hr. USP: 12 hr before joints are cut or anything goes on top |
| Shelf life | UM and USP: 6 months. Never on wet concrete. Not color-stable — expect color change |
Patch and joint products — from each PDS
| Product | Critical requirements |
|---|---|
| MavJoint JF (semi-rigid joint filler) | 1:1, gels in 45–50 seconds through the static mixer. Fill FULL depth, slightly overfill, shave flush with a sharp blade (30 min to 4 hr). Concrete 28 days old minimum — 90 preferred. Air/surface -25 to 120°F. NEVER in a joint designed to move — that gets a sealant. Not during the year's temperature extremes. |
| MavRapidPatch (polyurea patch) | 1:1, mix 20–30 seconds, use within 2–3 minutes. Traffic in 10 minutes, heavy in 30. Works 0–95°F. Dry silica sand to stiffen — never more sand than liquid, never solvent-thinned. Chase and vacuum cracks first. |
| MavPolyPatch (polished-concrete patch) | 1:1, mix 45–60 seconds — over 60 seconds makes it kick faster. 15 minutes on the floor. Grindable in ~1 hour (test a spot first). NO wet scrubbing before — slurry plugs the voids. Standing moisture in a void makes it foam. Cracks over 1/8" prefilled; voids over 1/2" get sand-blended material. |
| MavTints (pigment packs) | Exact ratios per resin: 1 pint/gal for HWU and ESD · 1 pint/2 gal polyaspartic · 1 pint/1.5 gal polyurea · 1 pint per 1, 1.5, or 3 gal epoxy (white and sandstone may take 2). Premix the pack, verify color and hide on a test area before coating the room, and never over- or under-tint. |
- Not this
The joint moves a little — fill it with JF anyway, it's tough stuff.
ThisThe JF sheet is absolute: moving joints get a sealant, never a rigid filler. Rigid filler in a moving joint shears itself and the edges.
- Not this
Skip the keyways, the mortar's thick enough to hold.
ThisEvery termination gets a 5/16" keyway. Unkeyed edges are how quarter-inch floors peel back from doorways.
Takeaways
- Urethane cement is on the floor within 3 minutes of mixing and abutting edges land within 10 — the wet edge rule is printed on every MavCrete sheet.
- Keyways, 5/16" wide by 5/16" deep, at every termination, doorway, drain, and joint — or the edge lifts.
- MavCrete UM, MavGrout USP, and MavSeal RCU carry a 6-MONTH shelf life. Check the date on the drum before it goes on the truck.
SOPSOP Section 2.7.8 — Field Non-NegotiablesSOP Section 2.10 — Safety SOP