Friction measurements on “anti-slip” floors under shoe sole,contamination, and inclination conditions

Friction measurements were conducted to study the effects of shoe sole, floor, contamination, and inclined angle of the floor surface on friction coefficient. The shoe sole samples included composite rubber outsole samples with and without V-shaped tread design. Unglazed ceramic tiles of both flat and tiles with molded profile design were tested. The contamination conditions included dry, wet, and glycerol-contaminated conditions. The inclined angles included 0°, 5°, and 10°. A Brungraber Mark II slipmeter was used. The results showed that all the four factors affected friction coefficient significantly (p < 0.0001). Flat rubber soles had higher friction coefficients than the soling samples with V-shaped tread design on all tested floors and inclined angles under wet conditions. Flat soles, however, had extremely low friction when tested on flat floors under glycerol-contaminated conditions. The floors with molded grooves perpendicular to friction measurement direction had the highest friction coefficients than all other floor conditions under both the wet and glycerol-contaminated conditions except the wet/flat sole/10° condition. A regression model with a cosine function was established to describe the relationship between friction coefficient and inclined angle of the floor under the experimental conditions. This model is statistically significant at p < 0.0001 with an R² of 0.97.