Concrete, ground, honed and sealed.
A polished concrete floor has nothing covering it, so everything that has happened to it is on show. It grinds and hones like a soft stone, and how it finishes depends almost entirely on how deep the grind goes.
Two very different floors get called polished concrete. One is mechanically polished: the slab itself ground with diamonds, densified with a chemical hardener and polished to a sheen that comes from the concrete rather than from anything applied. The other is a coating, a urethane or epoxy poured over the slab, which looks glossy on day one and behaves like plastic. They fail differently and they are restored differently, so identifying which one is underfoot is the first thing that happens.
On a mechanically polished floor the grind depth decides the look. A shallow pass leaves the cream, the smooth cement-rich layer at the top, and reads as an even soft grey. Going deeper exposes the sand, and deeper again exposes the large aggregate, the stone in the mix, which gives the terrazzo-like look people usually have in mind. That decision cannot be undone: once the aggregate is exposed it is exposed. It is worth being sure before the machine starts.
What goes wrong is wear and absorption. Traffic lanes dull first. Oil, wine and anything acidic soak into an unsealed or under-sealed slab and stain it, because concrete is porous and the stain is in the material rather than on it. Crazing, the fine map of surface cracks, is normal in a slab and becomes more visible as the floor is polished. On a coated floor the coating scratches, clouds in the lane and eventually peels, and no amount of cleaning brings it back.
Where the limit sits: concrete is not a uniform material. Colour varies across a pour, aggregate is not evenly distributed, and a patch where a wall once stood will always read differently. Polishing reveals what is in the slab, it does not even it out. Deep oil staining that has been in the slab for years often will not come out completely, and it is fairer to say that before starting than after.
Questions about polished concrete.
How long does a marble floor restoration take?
A large entry or open-plan floor is usually two to three days. A single room is a day. The time goes into grinding, honing, polishing and sealing, each pass across the whole floor, with drying time between the last polish and the sealer. Rooms can stay in use around the work; we move through the house in sections so you are never locked out of everything at once. The floor is walkable the same day it is polished and fully cured a day or two after sealing. We give you a schedule before starting so you know which rooms are out of action and when.
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