What is included in a polished concrete system?

More than the grinding and polishing passes. Before the first cut: protecting the slab while the building goes up, a mock-up that sets the finish, and a plan for joints and repairs. In the sequence: the metal grinding, a fill pass for pinholes, any dye, the densifier, the resin polishing, a guard and on a high gloss floor a burnish. After it: a cleaning and maintenance routine that keeps the finish. The grit sequence guide covers the passes themselves. This page covers the rest.

Why does polished concrete start at the pour?

Because the finished floor is the slab, and anything that happens to the slab during construction is still there when it is polished. Hydraulic oil from lifts, rust from stored steel, tire marks and rubbed in grime all stain it, and a stain that has soaked in does not always grind out. The curing method matters too. A floor that will be coated only needs the cure to leave nothing that stops a coating bonding, while a floor that will be polished needs it to leave the color even, and plastic sheeting laid on the surface can mark it. That is why polished concrete specifications call for the slab to be protected from the day it is placed, and why the curing method is agreed before the pour rather than after.

What happens to the joints on a polished floor?

They are filled, flush, with a semi rigid filler, usually a polyurea or an epoxy made for joints. On a polished floor the joint edges are exposed to hard wheels with nothing on top to protect them, and an unfilled edge chips. The filler supports the edge and is ground level with the floor. Joints are filled as late as the schedule allows, because the slab keeps shrinking and the joints keep opening for months. Some separation between the filler and the joint later on is expected, and the fix is to refill, not to call it a failure.

How is the finish specified?

By measurement, not by adjectives. "High gloss" means different things to different people, and it is a poor thing to argue about after the floor is done. The Concrete Polishing Council publishes an appearance chart that describes a finish by three measured properties: distinctness of image, which is how sharply the floor reflects, gloss, and haze. It uses all three because gloss alone is easy to push up without improving the floor. Write the target into the specification, agree it on the mock-up, and measure it on the finished floor.

Can polished concrete be colored?

Yes, usually with a penetrating dye rather than a film, so that the color is in the concrete and polishes with it. Where it goes in the sequence matters. Dye manufacturers commonly apply it to the opened surface just before the densifier, which then helps lock it in. A floor that gets daylight needs a dye whose data sheet says it will hold its color in UV. Color also changes what a repair looks like, because a patch has to match the dyed floor rather than plain concrete.

How do you maintain a polished concrete floor?

Keep grit off it and clean it with the right chemistry. Daily dust mopping or auto scrubbing with a pH neutral cleaner does most of the work. Grit tracked in is what wears the traffic lanes, so keeping it off the floor matters. Acidic spills can etch the surface if they are left, and strong cleaners can dull it, so the cleaning products belong in the handover. A densified floor is harder but it is still concrete and still somewhat porous, which is why a guard goes on and why it is renewed. When the lanes dull, a burnish and fresh guard usually bring them back without re-polishing.

Polished Concrete Floor System

The grit sequence gets all the attention, and it is only the middle of the system. A polished floor is decided at the pour and on the mock-up, finished by how the joints, repairs and color are handled, and kept by what happens after handover.

Quick answer

A polished concrete floor is the slab itself, ground and then polished until it shines, with a densifier and a guard. The grit sequence is the middle of the job. Before it: protect the slab from the pour onward, agree the finish on a mock-up, and plan the joints and repairs. Inside it: a fill pass, any dye, then the densifier. After it: a measured finish at handover and a cleaning routine that keeps it.

The ladder is the middle

Most of what is written about polished concrete is about the grit sequence, and this site is no exception. The grit sequence guide covers metal against resin, the four exposures, the four finish levels and where the densifier and guard go. The pricing guide turns that sequence into hours.

But a polished floor has no coating to hide anything. What the slab went through before the grinder arrived, how the joints and repairs were handled, and how the floor is cleaned afterwards all end up in the finish. This page is those parts of the system, in the order they happen.

Before the first cut

Decide whether this slab should be polished. Not every slab can give an even finish, and the polished concrete vs epoxy guide covers which cannot. That decision comes first, and is cheapest before any grinding.
Protect the slab from the day it is poured. On a new build the floor is the finish, so specifications for polished concrete call for it to be protected while the building goes up: drip protection under equipment, no parking or material storage on the slab, and non-marking tires. Oil, rust and rubbed in grime all stain, and a stain that has soaked in does not always grind out.
Settle the curing method before the pour. Under a coating, the question is what the cure leaves behind that could stop a bond, which the cure and seal guide covers. Under a polish, the question is also whether it leaves the color even. Plastic sheeting laid on the surface can mark it, which a coating would hide and a polish will show.
Agree the finish on a mock-up. A test area on the actual slab, run through the actual sequence, is how the exposure, color and sheen are agreed. Specifications commonly require one, keep it through construction, and judge the finished floor against it. A photograph of someone else’s floor is not a specification.

Joints and repairs

On a coated floor the coating covers the joint edges and the repairs. On a polished floor they are part of the finished surface, so each one is a decision rather than a step.

Fill the joints with a semi rigid filler. A polyurea or epoxy made for joints, filled flush and ground level with the floor. It supports the joint edges against hard wheels, which otherwise chip them.
Fill them as late as the schedule allows. The slab keeps shrinking and the joints keep opening for months after the pour. Some separation between the filler and the joint later is expected, and it is refilled, not treated as a failure. Tell the client that at handover.
Expect repairs to show, and decide how. A crack or spall repair is a different material from the concrete around it, and color matched repair products exist precisely because a plain one shows. Agree with the client whether repairs should blend in or read honestly as repairs, and if the floor is dyed, match the dye rather than the bare concrete.

The crack repair calculator sizes the filler from length, width and depth. The crack telegraphing page explains why a control joint is a planned crack and should not be treated like an accidental one.

Inside the sequence: fill and color

Two steps sit inside the grit sequence and are easy to leave off a quote.

The fill pass. The early metal cuts open pinholes and small voids in the surface. A grout coat, either a proprietary grout or the floor’s own grinding dust worked in with a binder, fills them, and the following passes grind the excess off. Skip it and the pinholes stay open in the finished surface.
Dye. Color in polished concrete is usually a penetrating dye, so it is in the concrete rather than in a film that the polishing would remove. Dye manufacturers commonly apply it to the opened surface just before the densifier, which helps lock it in, and that fits the densifier position the grit sequence guide gives. Where daylight reaches the floor, check the dye’s data sheet for UV stability.

Specifying the finish so it can be checked

“High gloss” is an adjective, and adjectives turn into arguments at handover. The Concrete Polishing Council publishes an appearance chart that describes a finish by three measured properties:

Distinctness of image, how sharply the floor reflects an object. This is closest to what people mean by a clear, mirror like finish.
Gloss, how much light the surface reflects.
Haze, the milky bloom that can sit in a reflection.

It uses all three because gloss on its own is easy to raise without making the floor any better. Put the target in the specification, confirm it on the mock-up, and measure the finished floor against it.

Grip

A smooth floor that gets wet needs grip treated as a specification decision, not an assumption. Agree with the client where the floor will be wet, and what they expect there, before the finish level is chosen, and keep topical products off the floor that were not part of that decision.

After handover: keeping the finish

Clean with a pH neutral cleaner. Dust mopping or auto scrubbing with a neutral cleaner does most of the work. Grit tracked in is what wears the traffic lanes, so keeping it off the floor matters.
Deal with spills promptly. A densified floor is harder, but it is still concrete and still somewhat porous. Acidic spills can etch the surface and oil can stain it if left. That is why the guard goes on, and why it is renewed.
Hand over the cleaning products. The wrong cleaner dulls a polished floor. Name the products in the handover, not just “keep it clean”.
Restore rather than redo. When the traffic lanes dull, a burnish and fresh guard usually bring them back without re-polishing, as the grit sequence guide explains.

What this page does not cover

The grit sequence. Grits, exposure levels, finish levels, densifier and guard timing are in the grit sequence guide.
Figures. Hours, grits, measured finish targets and cure times depend on the slab, the machines and the products. The hours are published on this site only where they are checked against the engine, in the pricing guide and the polished concrete cost calculator.
The sealed version. A ground floor finished with a clear film instead of a polish is a grind and seal floor.