Polished concrete in a food processing plant faces repeated washing, standing water and sanitation chemicals, so the floor is judged on hygiene, slip resistance and chemical tolerance rather than reflectance alone. The contractor confirms the substrate can carry a wet-service finish, agrees slip and drainage targets with food-safety and maintenance staff, and seals joints and edges to a washdown standard. This guide covers substrate checks, water exposure, slip zoning, drainage, process order and chemical compatibility.

Scope covers production bays, processing rooms, washdown and cleaning bays, drainage routes, and transitions to tiled or resin areas. Before mobilization, the PM confirms slab age, strength, moisture, existing coatings and joint layout; zones that fail these are logged in the tender assumptions rather than argued on site.

Hygiene brief and substrate baseline

Record slab age, compressive strength from cores or certificates, and condition at three points per 100 m²: sound, cracked, coated or sealed. A slab under 28 days still gains strength and may release bleed water; grinding early opens air voids in uneven paste. Test RH in probes; stop above 75–80% RH, holding surface temperature between 10 and 30 °C through grinding and sealing. Profile to CSP 1–2 heavy aggregate, CSP 3–4 medium removal, or CSP 5–7 fine near mirror finish; hollow patches are cut out before polishing.

Water exposure and moisture control

Classify each zone by how often it is washed and how long water stands. Light rooms see occasional spills; washdown bays see daily hose-down and standing water; raw-material and thaw areas see runoff and wet underfoot. A sealed polished slab resists water better than bare concrete, but porous patches, open joints and unsealed pop-outs take up moisture and can hold residue. Map wet zones before grinding so finish density, seal coat and joint treatment match exposure.

Wet-zone slip resistance and R class

Wet slip governs food-plant acceptance. Dry PTV should read ≥36 on walkable dry areas; wet PTV typically runs 10–20 points below dry, and wet zones must still clear DCOF ≥0.42 under wet testing. R10–R12 maps to exposure: R10 dry packing and storage, R11 light wash zones, R12 where hosing, standing water or greasy runoff is expected. Test slip at handover, recording readings per zone; a mirror finish in a washdown bay is a dispute waiting to happen. Keep coarser grit or sealed anti-slip texture in R11–R12 zones.

Drainage slopes, joints and coving

Drainage slope and joints decide whether water leaves the floor or sits on it. Check fall to drains: typical washdown floors fall 1–2% toward channels and sumps, with no ponding around equipment bases and corners. Control and construction joints are honed, filled flush and sealed along the water line; open joints trap debris and are hard to sanitize. Coved upstands at walls and columns close the gap where a flat floor meets vertical surfaces; check upstand continuity and seal adhesion before the washdown test.

Process sequence and densification

Run the sequence metal bond to resin in full passes. Metal starts at 16 or 20 grit for heavy removal and open aggregate, then 30 and 40 grit to level ruts and transitions; skip a grit only after a straightedge check clears deeper scratches. Resin follows 100, 200, 400, 800, then 1500 or 3000 grit; wet-service bays usually stop at 400–800 grit to retain texture. Apply densifier when dust-free; dilute silicate 1:64 ≈ 15 ml/L first coat, 1:128 ≈ 8 ml/L second coat, keep wet-working 20–30 minutes, wait 4–12 hours between coats.

Compatibility with washdown chemicals

Sanitation chemicals attack the seal and surface over repeated contact; confirm tolerance against the actual cleaners used. Caustic washdowns, dilute acids, degreasers and sanitizers differ in pH and dwell time, and a seal rated for occasional spills may fail under daily hosing. Record product names, dilution and contact time from the cleaning schedule, and run a patch check where compatibility is uncertain. Avoid harsh acids and pressure hot water; reseal before the seal dulls or etches.

Acceptance inspection and common disputes

Run the final inspection with the owner and maintenance supervisor against the schedule: slip readings, drainage run-off, joint and cove seal status, chemical patch result and cleanliness. Photograph each bay under the same lighting and keep readings in the binder. Frequent disputes are ponding at drains or corners, unsealed joints holding residue, gloss or texture mismatch between bays, and wet slip below target.

1. Check fall to every drain: pour water and confirm no ponding around bases, corners and channel ends.
2. Record PTV dry and wet, plus DCOF, in each washdown and dry zone before release.
3. Verify control, construction and isolation joints are filled flush and sealed along the water line.
4. Inspect coved upstands for continuity, adhesion and gaps at walls and columns.
5. Record chemical patch result and cleaning schedule; sign the punch list with due dates.

Handover, cleaning and recoating cycle

At handover, supply the finish schedule, grit sequence, seal products and dilutions, slip and drainage records and a maintenance note: wash down on the shift schedule, rinse chemical residue promptly, and do not leave caustic or acid cleaners standing on the seal. Protect fresh seal coats for walk-on and wet-service times, typically 48–72 hours before washdown resumes. Reseal on exposure: dry areas on a 3–5 year cycle, daily washdown bays on a 2–3 year cycle; re-check slip and joint seal after each reseal.