The BOT-3000 digital tribometer by Regan Scientific Instruments is an NFSI0-approved testing device to determine surface friction.
NFSI The BOT-3000 digital tribometer by Regan Scientific Instruments is an NFSI0-approved testing device to determine surface friction.

More than half — 55%—of slips, trips, and falls are caused by a hazardous walkway, according to the National Floor Safety Institute. Because of the high gloss produced by polishing concrete, many people assume it’s slippery. However, depending on which test method is used, the results may be confusing.

There is much at stake here. Concrete polishing contractors, who are riding the wave of the new concrete polishing business, cannot let building owners fear their customers, employees, and others will be afraid to walk on the surface. It’s bad for business for the building owner and the concrete polishing contractor.

For decades, manufacturers of floor finishes and polishes have relied upon the ASTM D-2047 (UL-410) standard for determining the slip-resistant properties of their products. This test method divided products into two categories, those whose dry Static Coefficient of Friction (SCOF) was equal to or greater than a 0.5 value and those whose SCOF was below the 0.5 value.

Products that met the 0.5 or greater value were classified as slip resistant, while products whose SCOF was below the 0.5 value were simply not classified. For many, this pass-fail approach created the perception that products meeting the 0.5 value were “safe” while those that did not were “unsafe.”

But this is not true. Just because a dry floor fails to meet the 0.5 threshold does not mean it is not safe, but rather that it’s not slip resistant. When floors other than those coated with a commercial polish are tested, they often fall below the 0.5 threshold. But polished concrete is not the same as a floor polish. Therefore, the ASTM D-2047 standard is not applicable. Furthermore, the ASTM D-2047 test method relies upon the use of a device called the James Machine, which is not portable and can’t be used outside of a laboratory. This makes filed testing impossible.

Hazardous walkways cause more than one-half of all slips, trips, and falls.
NFSI Hazardous walkways cause more than one-half of all slips, trips, and falls.

Because about 80% of all slip and fall claims occur on wet floors, it only seemed reasonable to test walkways under wet conditions rather than dry. In December 2009, the ANSI/NFSI B101.1-2009, “Test Method for Measuring Wet SCOF of Common Hard-Surface Floor Materials,” was published, establishing the first wet test method.

Rather than the pass-fail approach established by the ASTM D-2047 test method, the ANSI/NFSI B101.1-2009 standard identifies three individual risk categories, or Traction Ranges, to which each range describes the risk potential for a slip-and-fall.

Surfaces whose wet SCOF is 0.6 or greater are referred to as High-Traction. Walkways whose wet SCOF is below a 0.6 but greater than a value of 0.4 are defined as Moderate Traction, and walkways which possess a wet SCOF of less than 0.4 are defined as Low Traction. High Traction surfaces present the least amount of risk for a slip-and-fall claim, while Low-Traction surfaces present the highest risk.

High-traction range

A James Machine, which is used for the ASTM D-2047 test method, is not portable. This makes field testing impossible.
NFSI A James Machine, which is used for the ASTM D-2047 test method, is not portable. This makes field testing impossible.

When tested under the ANSI/NFSI B101.1-2009 standard, most polished concrete surfaces, regardless of grit size, usually fall in the High-Traction range. This raises the question: So how could polished concrete be slippery when dry but not when wet?

The answer is simple and has everything to do with the method by which the surface was tested. The ASTM D-2047 standard relies upon the use of a leather sensor, while the ANSI/NFSI B101.1-2009 standard uses a rubber-like compound called Neolite.

Dry leather is more likely to induce a slip on a smooth dry floor than rubber on a wet floor. Each test method has value, and should serve as a guideline to polished concrete contractors. However, currently, the only standard that applies to polished concrete is the ANSI/NFSI B101.1-2009 standard.

Polished concrete surfaces, like all walkways, should be kept clean and free of potentially hazardous materials such as paper dust, sand, soil, and liquids. Finally, in an effort to show compliance, it is important for end-users and polished concrete contractors to test their walkways per the ANSI/NFSI B101.1-2009 standard. This can be accomplished either way by the polishing contractor, the property owner, or an NFSI-certified walkway auditor.


Look for surface friction demonstrations of polished concrete at the Concrete Surfaces & Decorative Pavilion at World of Concrete.

Russ Kendzior is president of the National Floor Safety Institute and secretary of the ANSI B101 Committee for the Prevention of Slips, Trips, and Falls. Visit www.nfsi.org.