the process

"Concrete Processing" is: the act of changing an existing concrete surface by means of a mechanical process that involves cutting and/or refining the surface to a desired finish.

Polished Concrete is one of many end results in what is the "processing" of the concrete surface by mechanical refinement through the use of multiple abrasives measured in grits. This is the same processes used to polish stone such as marble and granite.

Currently, the industry breaks down the process of Concrete Polishing into grinding and polishing. Some within the industry simply use the word "polishing" for the entire process.

The process of Polishing Concrete consists of three consecutive categories: grinding, honing and polishing. Each category is then broken down into multiple steps, consisting of consecutively finer grit abrasives. During the processes a densifier or hardener is applied that is absorbed into the concrete creating a chemical reaction that makes the concrete more dense and hard.

Recent advances in polishing equipment and techniques has allowed concrete to be ground, honed and polished to a high polish with clarity of reflection and depth when looking straight down that does not use any type of coatings or sealers. Grinding, Honing and Polishing concrete is similar to sanding wood or buffing your finger nails with progressively finer abrasives. The process is performed with large planetary head machines where the main head rotates in one direction and smaller satellite heads spin in the opposite direction.

"Polished Concrete" is: the processing of the concrete surface through means of a mechanical process that uses an abrasive medium where each step is refined to its purest possible form on a microscopic level from one progressively finer abrasive to the next until the desired level of 'polish' is achieved.

The result is a beautiful, durable and efficient surface which eliminates the need for carpets or tile that requires expensive replacement, maintenance and use of harsh cleaning chemicals. The natural concrete floor can be customized and provides long-lasting beauty and ease of maintenance with environmental benefits.

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Maximum "clarity of reflection" and "durability" of the surface is determined by the precision with which a contractor executes the grit sequence and the full refinement of the concrete surface. Even if the desired result is not clarity of reflection or a glass like finish, each grit must be fully refined to obtain the maximum durability and a clean crisp look of the finished surface. Full refinement of the surface extends beyond replacing scratch patterns from one progressively finer grit to the next. Once a scratch pattern has been replaced additional refinement of the surface can be achieved.

It is imperative not to skip a grit in the processing sequence and when transitioning from metal to resin bond abrasives the first resin bond grit used must be one grit lower than the last metal grit used. For example, if the last metal grit abrasive used is a 100 then the first resin grit abrasive used must be a 50 grit.

IMPORTANT
The Craftsmanship of the
Polishing Processes

The processes of polishing concrete is very technical in nature and requires real craftsmanship.

Just because two contractors have the same grit sequence specified the significant factor to take into consideration is that maximum refinement of each grit is performed. Refinement goes beyond replacing the scratch pattern from one grit to the next. Some contractors reduce refinement to the process of replacing the scratch pattern from one grit to the next. This is a misconception. Once the scratch pattern has been replaced from the previous grit, further refinement of the concrete should take place.

Contractors need to understand and be able to explain what maximum refinement of the surface means.

There are many variables a contractor has to contend with throughout the processes. Knowing what these variables are and how do deal with them separates the knowledgeable contractor and the contractor just going through the motions of the processes.

Variables Within Contractor Control

Variables Outside Contractor Control

Is the concrete hard or soft?
What imperfections need to be removed?
Is the surface level and flat? Level means the whole slab. This refers to the angle at which the whole slab sits. Flat means areas of the slab. This refers to high and low spots within the slab.
What type of concrete mix is it? The concrete for a residential garage is different from the concrete used on bridges, roads and warehouses.
What types of ad mixtures were used? Retarders make the concrete cure slowly, Accelerators make it dry faster, Air-entrainers add and distribute air into the concrete, Plasticizers increase the workability of the concrete, A variety of fibers and polymers may be used to add strength, Aggregate (some with different densities) may vary depending on geographical location.
Was the concrete vibrated to remove air?
How was it troweled? By hand? Mechanically?
Were any additional coatings, glues or mastics applied?