Coefficients of static and dynamic friction of ceramic floor tiles: proposal of new method of surface roughness determination

Among the most important properties of ceramic floor tiles, the static and dynamic coefficients of friction assume an important role. The literature and current standards regarding ceramic floor tiles suggest different methods for determining the values of the coefficients of static and dynamic friction; however, all methods present limitations of implementation, and it is common for them to produce different values and hence specifications for different applications. In the present study, tests were conducted on the products with different topcoats and roughness to determine the coefficient of friction using the standards NBR 13818, ANSI A137.1, DIN 51130, and UNE-ENV 12633 and our proposed methodology. These values were compared with the roughness measurements obtained by mechanical contact profilometry. Additionally, empirical human evaluation of the roughness was performed. The trials indicated very different results on different experimental equipment for the same type of surface. The roughness test yielded parameters that correlate well with the empirical evaluation. The study shows the need for searching the uniformity of standards because each methodology produces different (even uncorrelated) results.