Tips for Decorative Concrete Contractors on Polished Concrete - Planning the Finish
The latest in decorative concrete is polished concrete floors. Achieve a better finish by spec'ing a job from the ready mix concrete through the protection process.
The success of a polished concrete surface doesn't rest solely with the concrete processing steps. Careful planning of the project from mix design through final protection will help a contractor achieve a successful end.
Processed concrete, whether honed to 800 grit or polished to 3,000 grit, is a growing area of decorative concrete. Over the last decade or so, the concrete processing industry has experienced a learning curve, but finally architects, designers and engineers are giving concrete processing the green light on an increasing number of projects. This is an exciting opportunity for concrete polishing contractors and manufacturers of equipment and supplies to prove what they have been saying for a long time - there is no other flooring option currently available that is as durable, has as low a maintenance and life-cycle cost, and can be renewed on site as easily as concrete. Every day I see more and more plans that specify polished concrete over VCT, carpet, epoxy and other flooring materials.
Although concrete processing technology has made great strides in the last few years, I see two problems still facing the industry. First, almost all specifications I see are vague in respect to the installation process, i.e., the actual steps and techniques a contractor uses in polishing a floor. Second, if the concrete has yet to be poured most current specifications do not take into consideration other factors that affect the installation process and final appearance of the floor, such as mix design, placement, finishing, curing, joint placement and protection. Final results of a polished concrete floor are largely dependent on the quality of the concrete a contractor is given to work with. When there is an opportunity to specify these other factors, a floor will turn out significantly better than if only the processing procedure is specified.
Specifying a polished floor
When a designer or architect is specifying a processed concrete floor, the first step is to determine the desired finish. Considerations need to be made for the surface cut, clarity of reflection and decorative applications such as coloring, saw cuts, engraving, seeded decorative aggregate, etc.
After the desired look has been determined, specifications for completion need to be written. For new concrete the specifications start in "Division 3 - Concrete." Within this section you will find the specifications for mix design, finishing, curing, control joint placement, protection and sometimes the processing process. If the processing process is not listed in Division 3 it will most likely be found in "Division 9 - Finishes." Following are some brief points to take into consideration when specifying a "Polished Concrete System."
Mix Design
- Mix design varies from one geographic region to the next as a result of available aggregates and weather conditions.
- If possible, do not air-entrain; if entrainment is necessary do not exceed 3 percent.
- Keep fly ash to a minimum, not to exceed 20 percent of the cement weight.
- Do not use calcium chloride-based accelerators.
- Use a 3,500 - 5,000 psi at 28 days mix.
- When exposing aggregate, understand how the aggregates will look when polished and how well that polish will hold up compared to the concrete's finished surface.
- Final color of dried mix if the floor does not receive stain.
- Final color of dried mix will affect the overall color of stains.
Finishing
- Floor Flatness (FF) above 40 will minimize a wavy appearance in a floor when finished.
- Mechanically trowel the surface to the point right before burning and do not allow the power trowel to run dry.
- In areas that receive hand troweling, make sure the concrete has been well consolidated and troweled as tight as possible.
- If a fine aggregate finish with minimum aggregate has been specified, thoroughly floating and tamping will help bring more cream to the surface.
Curing
- « Previous Page
- 1
- 2
- 3
- Next Page »





