Polished concrete is a very viable flooring option for commercial and retail facilities, as well as schools and factories. When the slab's surface is ground, polished, and cleaned correctly, it is safe, performance-oriented flooring with a design flair. The natural porosity of polished concrete, along with the flat surface that grinding produces, provides a safe flooring option, dry or wet.
Now that many are embracing polished concrete as a option, let's address how safe a polished concrete floor is.
First, we reached out to polished concrete to stop spalling and dusting in industrial applications. Second, we added color as a design element in commercial and retail operations. Third, we have started to see how everyone is focusing on polished concrete in sustainable, Leadership in Energy and Environmental Design (LEED)-directed projects.
Safety is part reality and part perception. About 50% of slip and falls are perceptually caused. Someone sees a shiny surface and he naturally tenses up, and due to this tensing up, he falls.
Your customer, the building owner, cannot eliminate slips and falls. But he can minimize them through analysis of floor type, along with proper cleaning and walk-off mat systems.
Any surface can be slippery if it is either wet or not cleaned regularly. Dust and dirt can act as ball bearings and cause a slip and fall just as easily as liquids can.
While there is no set, definitive means to judge safety, there are guidelines. At one time, OSHA and the Americans with Disabilities Act provided specific numbers, but today these figures tend toward guidelines. The low-end numbers indicate a potentially unsafe slip area, and higher numbers indicate a trip hazard.
Generally, 0.5 is considered the minimum reading indicating a floor that is safe from slips.
The bottom line is that concrete polishers must utilize consistent testing methods on their finished projects, and they need to test both dry and wet conditions.
Many intangibles affect safety. These including the type of sole of a shoe, (neolite, rubber) whether new or old soles; the weather; contamination of the floor; lighting; and the person's gait. Still, there is no single method for testing all of these variables.
While there also is no consistent test method, the American National Standards Institute is evaluating and creating a consistent standard. Today, the public must deal with no fewer than nine different ASTM recommended testing standards, in addition to two design standards. The test standards address both wet and dry floors, floors with waxes and polishes, ceramic tile, workplace environments, and more. It is very frustrating.
When you look at polished concrete versus polished granite or marble, most people assume that they would have the same Static Co-efficient of Friction (SCOF) as each other. But the polished concrete will be more slip-resistant, especially when wet.
The reason for this is that while granite and marble are formed over time under pressure and heat, making for a generally non-porous surface, polished concrete has many micro-pores in its surface. It is a fallacy that the polished concrete becomes denser as you move up in grit level, say from 400 to 800, or 800 to 1500. In fact, concrete will never be as dense in the polished stage as it was when the surface was freshly consolidated during finishing.
The only change to the concrete surface during grinding and polishing, other than clarity and gloss changes, is that the height of the scratch pattern from the diamonds is cut in half during each successive step. Density and pore closing (to some degree) occurs during chemical densification, but not during the diamond stages.
The intelligent polisher and educated owner will test the floor with a recognized slip tester, and then maintain a log of all of the results.
For instance, L&M Construction Chemicals utilizes the testing program of the National Floor Safety Institute (NFSI) to certify not only a densified floors, but also the floor surface following cleaning.
In addition to L&M, NFSI has been recognized or sponsored by cleaning solutions manufacturer Tennant, the International Sanitary Supply Association, and State Farm Insurance. Polished concrete floors that receive an 800-grit finish with our FGS PermaShine Plus densifier and FGS Conditioning Cleaner, are both rated as High Traction Floors by NFSI.
Leaving dirt at the door
Measuring the SCOF of a floor is only part of the equation. A proper walk-off mat system leading 10 feet to 15 feet into a retail or commercial building will trap most of the wet and dry soils before people track them onto the polished floor.
It is important to remind your customer to keep the walk-off mat system clean, or it will just extend the dirt further into the building. Walk-off mats act as a sink for soil and dirt, so they must be cleaned regularly, as they can only hold so much material.
Cleaning with both the proper cleaner (neutral or low alkaline), and the proper amount of cleaner, will ensure that you both have a clean, dirt- and dust-free surface, and also one without traces of a slippery residue.
Finally, maintain a log of slip testing results performed consistently with the same equipment at regular intervals. In measuring the static coefficient of friction of a polished concrete floor, always maintain records of the test measurements, both from a visual gauge of your grinding and polishing and to eliminate or minimize punitive damages in light of a slip and fall in your office, or on your project. These tests also provide proof of your company's compliance with OSHA and ADA guidelines.
Peter Wagner is the director of marketing and sales support for L&M Construction Chemicals of Omaha, Neb. He has been involved in polished concrete for nearly 10 years, as an installer in the Pacific Northwest, and in marketing and sales support. He previously was involved in the stone restoration industry in Portland, Ore. E-mail[email protected]