Polished concrete glossary of terms & finishes
15 technical terms, diamond tooling stages and finish classes explained in plain English.
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Key polished concrete terms explained
Aggregate Exposure Class
Visual grading describing how deeply the concrete surface paste is ground back—from Class A (cream/paste finish) and Class B (salt-and-pepper fine sand) to Class C (full 8–20 mm coarse stone exposure).
Burnishing (High-Speed Pad)
Final high-rpm pass with a diamond-impregnated hog-hair or resin burnishing pad that heats the guard treatment to micro-fuse pores and build specular gloss.
Colloidal Silica Densifier
Nanoparticle liquid hardener sprayed onto ground concrete between metal and resin tooling stages; it reacts with free calcium hydroxide in the slab to form insoluble calcium-silicate-hydrate crystals in the pores.
Control Joint (Saw-Cut)
Planned contraction cut sawn to one-quarter or one-third of slab depth within 12–24 hours of power-trowelling so drying shrinkage cracks occur neatly along straight lines rather than meandering across the room.
Cream Polish
Surface-level diamond polish using resin-bond pads (or fine hybrid pucks) on a hard power-floated slab that retains the natural cement paste swirl without exposing the underlying sand or stone.
Distinctness of Image (DOI)
Optical reflection sharpness rating from 0 to 100 measuring the crispness of overhead reflections in a polished concrete floor—distinguishing true flat mechanical diamond refinement from a bumpy topical sealer.
Grit Progression Sequence
Stepwise diamond tooling schedule—typically 30/40 and 80/100 metal-bond segments followed by 100, 200, 400, 800, 1500, and 3000 resin-bond pads—where each grit removes the scratch pattern of the previous pass.
Grout Coat (Pin-Hole Filling)
Latex-modified cementitious or polyurea pore-filler trowelled tight across the floor after the 80-grit or 100-grit pass to plug tiny air voids and pull-outs before densifying and resin polishing.
Metal-Bond Diamond Tooling
Sintered steel segments containing industrial diamond grit mounted under planetary grinders for the heavy initial flattening and aggregate-exposure cuts on hard Irish limestone or granite slabs.
Micro-Topping Overlay
Polymer-modified cementitious skim coat trowelled at 2–4 mm over worn or patched substrates where the existing slab cannot be mechanically ground directly.
Pan & Blade Power-Floating
Ride-on or walk-behind rotary trowel stage carried out while fresh C35/40 concrete stiffens, compacting the top 3 mm paste into a dense, flat crust ready for diamond polishing.
Planetary Counter-Rotating Grinder
Three- or four-head floor grinding machine whose satellite heads spin opposite to the main drum, eliminating directional swirl marks and producing uniform flatness across the slab.
Resin-Bond Diamond Pads
Phenolic resin pucks embedded with fine diamond abrasives (100 to 3000 grit) used after densification to close the concrete surface from a matte hone up to a mirror sheen.
Salt-and-Pepper Finish
Light 1–2 mm diamond cut that skims off the top laitance skin to reveal fine river sand speckles and occasional pea-gravel tips without cutting deep into the coarse stone.
Stain Guard (Penetrating Impregnator)
Breathable lithium-silicate or fluoropolymer sealer buffed into the finished floor at the end of polishing to give a 2–4 hour window to wipe up red wine, coffee, oil, and vinegar spills.
Questions people ask
How much do polished concrete floors cost?
Most floors are €90 to €150 a m². Large floors with a standard finish start at €55 to €60 a m²; small floors and high-end finishes start at €120 a m². Rural jobs add €20 to €30 a m². See our price guide.
Can you polish an existing concrete floor?
Often, yes, and then the grinding and polishing is the whole cost. Whether yours polishes well depends on the concrete, what's been stuck to it and the cracks. A test grind shows it. See polishing an existing floor.
How long does it take?
A new slab cures for at least 28 days before the grinding starts. The polishing itself takes days, not weeks, depending on the size and the finish. How long it takes.
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