When it comes to installing a floor that looks terrific, requires very little maintenance, performs dependably long-term, offers superior sustainability, and meets budget, sometimes it is not only how you start but also how you finish.

Dry polished concrete offers a great opportunity to revitalize and rejuvenate floors in a long-term cost effective manner while achieving an attractive, durable and affordable 21st century look.

Case in point: To fulfill all those goals for durable, non-slip flooring in the lobby and other public areas in the Norma Lea Beasley entrance hall, a recently completed major addition at the University of Arkansas Law School, in Fayetteville, the architects turned to an age- old building material enhanced with a new twist made possible by innovative technologies and installation techniques. Enter dyed and dry polished concrete.

When the project was still in the planning stages, representatives of the university and the law school considered using fire cracked black granite because they liked the look. But preliminary pricing for the granite came in at about $32 a square foot, far exceeding budget.

Through value engineering of flooring alternatives, the decision- makers honed in on dyed and dry polished concrete as a very good- looking and sturdy alternative, which competes very favorably in cost against not only granite and marble but also against porcelain tile and terrazzo and is competitively priced against linoleum and vinyl composition tile.

Concrete flooring, dyed and dry polished, will run less than the cost of a terrazzo or stone floor and be cost competitive with other flooring materials and yet can feature the same type of decorative pattern in the similar choice of colors as either granite or terrazzo. The savings achieved by using polished concrete on a large project can be substantial notes polished concrete consultant David Stephenson, American Concrete Concepts Inc. (ACCI), Springdale, Arkansas, the contractor for the polished concrete flooring.

In addition to serving as the eye-catching floor for the entry area, exposed concrete is used for the treads and landing of a dramatic hanging staircase overlooking the entrance, a study room, a café area in the reading room, and the corridors to the original building. Even the stairs and landing themselves were dyed and sealed to closely match the polish. In all, the polished concrete covers about 10,000 square feet of the approximately 60,000 square foot addition.

While concrete as a modern building material has been around since the mid-nineteenth century, only in the last few years has polished concrete really come into its own.

Recent innovative construction chemicals to dye and densify concrete and new dry polishing techniques that utilize diamond disks in grinding machines provide an efficient and cost-effective way to transform a bland concrete floor into a highly appealing polished surface that outperforms most floor covering choices in maintenance. Once completed, polished concrete does not require waxing, polishing, or other periodic protective treatment and certainly would not look tired after a day’s worth of student and faculty footwork on it. Also, a polished concrete floor has no seams and no grout, thereby eliminating any breeding ground on the floor for mold or mildew. In fact, depending upon the system used, it is possible to save up to 65% on maintenance costs compared to other flooring options.

Just about any structurally sound concrete floor can be dyed, dry polished, and chemically hardened and densified (which essentially is the hardening of the top wearing surface). New floors, however, require a minimum wait after the pour, normally 28 days, to allow the concrete to cure properly. The dyeing process is performed after the floor is polished to the desired level. Within minutes after the dye is applied, the installer performs an additional polish and then applies a hardener/densifier to extend durability and dramatically reduce ongoing maintenance costs.

For the law school project, Stephenson used the dry grinding process along with specific manufacturer-recommended techniques and products to smooth, polish, color and densify new and existing concrete floor surfaces.

His crew performed the initial preparation steps a few weeks after the concrete was poured, while other crews were onsite still doing the steelwork. They then returned at the end of the construction phase, about nine months later, to color the concrete and complete the polishing. At that time, the stair treads which were too narrow to accept the process’s machinery, were dyed separately to match the color of the polished concrete flooring and sealed with penetrating topical sealant.

“It was an important consideration that the treated (polished) concrete floor meets the NFSI (National Floor Safety Institute) standards for certification as a “High Traction” floor – that it retain its non-slip qualities even when it becomes wet and complies with ADA and OSHA requirements for interior floor surfaces,” points out project manager and lead architect Dan Fowler of Cromwell Architects/Engineers, in Little Rock. The courtyard walkways, which were not polished, received a light broom finish to provide the desired non-slip properties for exterior concrete. The matching of the interior concrete color with the exterior concrete color ensured easy visual transitions throughout the building complex.

Concrete dye is available in many attractive, translucent colors in varied intensities ranging from relatively light to rich and extremely vivid. Both new and renovated polished concrete floors can be permanently dyed most any color or combination of colors (from muted to razzle dazzle), with the exact hue complementing the palette of other finish materials (walls, seating, desks and adjacent floors).

That capability was an important factor for the decision-makers for the project, who ultimately selected a warm dark gray dye that complemented the slate walls adjacent to the hanging staircase. It also picked up the color tones in the sculptures installed in the interior courtyard. The dye, a combination of several blended colors in various intensities, was applied just before the final polishing of the floor with the finest grit.

The architects also wanted a simple unobtrusive joint pattern, which ACCI achieved by cutting straight lines lightly into the surface both as control joints at column lines and for a bit of a pattern in the floor.

“Polishing the surface created the highly reflective glimmer and glisten surface we were after,” Fowler explained. Indeed, in the café area, light streaming in from the wall of floor to ceiling windows and reflecting on the polished concrete capitalizes on the benefits of daylighting, which was not a consideration in the specification process but which turned out to be a nice perk. Also, the reflection of ceiling-hung lighting on the floor adds visual interest from anywhere along the hanging staircase.

After completion of the dry grinding, dyeing and polishing process, the concrete surface is now somewhat porous. An important part of the system, and the best way to ensure long-term durability, is to apply a compatible penetrating chemical hardener/densifier which will harden and protect the surface wear layer of the floor.

For example, on his dry polished concrete projects, Stephenson uses a waterbased, solvent-free VOC-free, odorless and non-toxic hardener/densifier. The “green” hardener/densifier chemically reacts with weak components within the concrete floor, calcium hydroxide and calcium carbonate, to form a hard, dense crystalline compound, calcium silicate hydrate (C-S-H) in the top wear layer (a depth of about 1/16 of an inch). That hard crystalline formation does not, however, completely seal the surface. It enables excess moisture and water vapor to escape from within the concrete without a negative effect that all too often happens with other flooring materials. Rather, the crystalline formation becomes a component of the concrete rather than a top sealing film that can scratch, chip, peel or discolor as do film forming coatings and floor waxes.

The added strength and wear resistance helps preserve the highly polished ‘new’ look for many years. The chemical interaction also eliminates dusting of the concrete surface and reduces micro-pitting, the process by which the wear surface microscopically deteriorates over time by abrasion.

Restoring concrete floors in school buildings minimizes the environmental impact compared to demolition and new construction. The process can be completed in just a few days either at night, on weekends, or during school vacations without disturbing class schedules.

In fact, a system that utilizes highly efficient HEPA filter vacuum air purification technology to collect dust generated during the dry abrasive grinding and smoothing process keeps the jobsite atmosphere virtually clear of airborne dust. The dust is captured and collected in lightweight bags suitable for landfills.

Using an installer trained and certified by the manufacturer of the components of a dry polished concrete flooring system ensures correct installation. From initial evaluation of existing concrete and proper preparation for a polishing/dyeing/densifying sequence to grinding of the surface and then application of dyes and densifiers.

Other features of polished concrete contribute to its being an excellent high performance choice for greener, healthier schools and universities.

• Polished concrete can help buildings gain up to five U.S. Green Building Council’s certified LEED (Leadership in Energy and Environmental Design) credits under various categories, including Materials and Resources, Energy and Atmosphere, and Low Emitting Materials.

• Depending upon the colors, the floor can reflect as much as 35% of the light, saving on the energy used for lighting. The lower heat output from the lamps, in turn, reduces the demand on the air-conditioning system in warm weather. Moreover, a concrete floor absorbs heat during the day and radiates that heat out at night. This delay in the cycle can further lower HVAC energy costs.

• It is very easy for flooring professionals to use multiple colors in various sections of the floor and/or incorporate school logos and emblems as well as geometric and free-form designs. It wears well underfoot, year after year, in lobbies, classrooms, cafeterias, hallways, and anywhere else a great looking and durable floor is an asset.

While the process for fully treating concrete to optimize goals is fundamentally the same for every installation, decision-making for each project always includes: 1) choice of color (if any) and the intensity of color and 2) the level of shine.

For most any academic building, flush with tired looking, removable coverings on concrete (such as worn out carpeting, linoleum or VCT), dry polished concrete offers a great opportunity to revitalize and rejuvenate floors in a long-term cost effective manner while achieving an attractive, durable and affordable 21st century look.

Greg Schwietz is president of L&M Construction Chemicals, which produces chemical treatments for the construction, repair and protection of concrete and is the developer of the FGS/PermaShine concrete polishing system. Visit them at: www.lmcc.com or at: www.fgs-permashine.com or call: 800.362.3331. Mr. Schwietz can be reached at: gschwietz@lmcc.com.

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