Cuviello Concrete and Terrazzo Polishing

For Architects & Specifiers

Concrete

Not all concrete is a good candidate for processing and polishing. When working on existing concrete, results are largely dependent on the quality of concrete Cuviello is given to work with. For example, residential concrete has a low PSI, is often hand troweled, and rarely is there a concern for mix design, finish methods or the curing processes.

However, most existing commercial concrete that has not been damaged is of sufficient PSI and has been finished in a manner (with a trowel machine) that will allow for excellent results.

Variables such as aggregate, color variations, miscellaneous contaminates, cracks, patterns left by previous floor covering, existing stains, nail holes from previous walls, patched areas, and flatness can affect the final appearance and results.

On new projects, final results are significantly improved when the concrete slab is poured within specifications that lend it to the processes. A polished concrete application needs to be viewed as a total flooring system that includes several components:

• concrete mix design
• finishing methods
• curing methods
• control joint placement
• polishing process

A slab poured within specifications that are conducive to the process will eliminate a significant number of variables and provide improved finish results over an existing concrete slab.

Visit www.greenenduranceflooring.com for step by step specifications.

When it has been decided that processed concrete is going to be used as a finished floor, there are several visual facets that need to be determined. Considerations need to be made for the surface cut, clarity of reflection, and decorative applications such as coloring, saw cuts engraving, seeded decorative aggregate, metal strip placement, etc.

Remember: a processed concrete surface is still concrete -- it is consistently inconsistent. Each individual concrete pour, from one truck to the next, will have differences. Concrete varies in color, concrete cracks, and concrete is inconsistent. Will you and the customer's expectations be met?

There are four visual aesthetics that have to be specified:

• Aggregate Exposure
• Clarity of Reflection
• Coloring
• Planned and Existing Characteristics

Aggregate Exposure

• Surface Cream
• Fine Aggregate
• Medium Aggregate
• Large Aggregate

The goal is to refine "to" and remain "within" the desired layer and make it as consistent as possible throughout the entire area being processed. These layers can vary in thickness throughout the surface and the area of the slab being processed. As a result, there may be random exposure of varying degrees of exposed aggregate through a floor. This is one of the many reasons why achieving the correct Floor Flatness (FF) at the time or placement and finishing is critical.

Surface Cream is the very top layer of the concrete that is made up of the troweled cement paste that contains primarily the cement fines of the mix. The goal is to stay primarily within the Portland cement paste, resulting in little to no aggregate exposure. There can be several layers within the cream that vary in color. 1/32" - 1/64" is removed from the surface.

Fine Aggregate is the layer just below the cream and is made of the fine aggregate, primarily sand and very small stone of various types that lend themselves to a "salt and pepper" look. To reach this layer, the cream-cement fine layer is removed by grinding the surface. This layer is the purest, the most consistent in color, and has the fewest imperfections. 1/64" - 1/8" is removed from the surface. Small amounts of medium aggregate may appear at random locations.

Coarse Aggregate is the layer below the cream and fine aggregate layer. It is made of the coarse aggregate within the concrete mix. To reach this layer, the cream-cement fine and the fine aggregate layer is removed by grinding the surface. These aggregates may be the aggregate used in the concrete mix, or decorative aggregates seeded into the surface at the time of the pour, such as recycled glass, landscaping stone, nails, nuts, bolts, sea shells, etc. There are three degrees of Coarse Aggregate: Small, Medium and Large. 1/8" - 1/4" is removed from the surface.

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Clarity of Reflection / Distinction of Image

Clarity of reflection, also known as distinction of image, refers to how defined, crisp and clear the reflection of objects are when looking straight down (not out at an angle) into a surface. There is a difference between a crisp and clear reflection and a muffled one.

• Ground
• Honed
• Semi Polished
• Highly Polished

Ground concrete has a flat appearance with no reflection.

Honed concrete will have a well-refined and even appearance; the finish will have a muffled but crisp shine that lacks defined clarity of reflection. A honed finish stops at 200 or 400 grit. Note: a 400 grit honed finish still has a muffled sheen and will have higher clarity of reflection than a 200 grit finish.

Semi Polished concrete will have greater reflection with a crisp appearance. A semi polished finish stops at 800 grit.

Highly Polished concrete will have depth and clarity of reflection like a mirror. A highly polished finish stops at 1,500 grit. If a floor has been properly processed, there is no need to go higher in grits.

In many respects, the process of mechanical polishing with bonded diamond abrasives is very technical - in simple terms, two contractors can have the same equipment, abrasives, supplies, etc. with the only variable being the rate at which the equipment is being moved across the surface in a liner motion - and the results between the two contractors will be different, even though both contractors finished at the same grit. Cuviello's proprietary system uses scientific testing equipment (metrology measurement and distinction of image meters) to quantify the finished floor.

By quantifying results using scientific equipment, the subjective nature of the Concrete Polishing process is eliminated. Owners can be assured that they are receiving what they are paying for, and are guaranteed a floor with high aesthetics and superior durability.

Both of the floors below were polished to a 1500 grit. The lack of clarity of the floor on the left is the result of a polishing process that was rushed.

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Coloring

There are four primary ways concrete is colored:

• Integral - Performed at the time of pour. Is considered environmentally friendly and is UV stable.
• Water Based Dyes - Performed during the polishing process. Is considered environmentally friendly and is UV stable, but not UV resistant.
• Solvent Based Dyes - Performed during the polishing process and can meet VOC requirements when used with acetone, since acetone is exempt from VOC requirements. 40 CFR 51.100(s). These dyes are UV stable, but not UV resistant.
• Acid Stain - Performed during the polishing process. Is not considered environmentally friendly, but is UV stable.

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Planned and Existing Characteristics:

Concrete contains multiple variations, like a piece of wood. Each piece of concrete has its own character.

Planned Characteristics

Metal Strips, Stained and Exposed Aggregate

Recycled Glass Mixed with Black Cement

Existing Characteristics

Two different mixes separated by a cold joint. See the different aggregate?

A patched crack.

Surface crazing created by improper curing or a mix with too much water.

Pieces of wood in the concrete.

Foam in the concrete.

Rebar

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Other Specification Requirements:

Note: Below are some of the very basic specification dos and don'ts. For help with specifications for mix design, finishing, curing, control joint placement, the polishing process, and protection, contact us. For a step by step process, visit www.greenenduranceflooring.com.

SOME (BUT NOT ALL) OF THE RESULTS FROM POOR PLANNING THAT CUVIELLO CONCRETE CAN HELP AVOID

Why Use Zip Strips? Baseboard Not Big Enough to Cover Felt:

Two Pours from Two Different Trucks:

Improper Curing and or Mix Design:

Low Floor Flatness (FF) Numbers:

Poor Mix Design:

Improper Floor Protection: