Implications for the Development of Slip-Resistance Standards Arising from Rank Comparisons of Friction-Test Results Obtained Using Different Walkway-Safety Tribometers Under Various Conditions Available to Purchase

This paper studies the extent to which different tribometers consistently rank the slip resistance of a series of different ceramic tiles, as measured by a number of techniques. An accelerated abrasion treatment was used to determine how the slip resistance might change with wear in service. It forms part of a wider study of the slip resistance of stone, concrete, vinyl, rubber and other pedestrian surfaces. Although most techniques ranked the tiles in a similar order, there were some notable exceptions. Underestimation or overestimation of available slip resistance may cause significant problems, whether in the evaluation of a new product or an existing walkway surface. It is important to determine when specific tribometers may give “incorrect” results on particular types of surfaces, in order that a more reliable assessment can be made. This may require the use of a different technique, a dissimilar test foot, or modified test procedures or parameters. When a hard rubber test foot was used, the slip resistance tended to reflect the altered surface roughness of the abraded tiles, but when a resilient rubber was used, there was a general increase in the slip resistance. These results confirm the complex interplay between surface topography and choice of test foot. The results also indicate that current commonly used test methods can yield results that poorly predict the traction available to a pedestrian, either when the product is new or after the surface wears. This study found that the manually-pulled 50-pound drag sled (as used in ASTM C-1028) was incapable of satisfactorily distinguishing between the wet slip resistance of ceramic tiles. The pendulum tribometer (used according to AS/NZS 4586, with TRRL rubber, similar to ASTM E-303) provided more reliable results than the English XL Variable Incidence Tribometer (used according to ASTM F-1679).