ABSTRACT
The effect of surface roughness on the frictional behaviour of recycled rubber tiles is discussed. Experiments were carried out by the sliding of the bare foot against smooth and rough groups of rubber tiles of different thickness. The friction coefficient was investigated. Experiments were carried out using a test rig designed and manufactured for the test. Loads were applied by foot up to 700 N. The normal and friction forces were measured to determine the static friction coefficient.
It was found that, for tiles made of recycled rubber, surface roughness had insignificant effect on the frictional behaviour. Generally, friction coefficient slightly increased with increasing the tile thickness. In the presence of water on the sliding surface, rough surface displayed higher friction values than the smooth one. Generally, friction coefficient decreased with increasing tiles thickness. Values of friction for detergent lubricated surfaces were lower than that observed for water lubricated surface. In the presence of sand particles on the sliding surface, friction coefficient increased for rough surface and decreased for smooth one with increasing the tile thickness. For tiles wetted by water and contaminated by sand particles rough surface displayed relatively higher friction than smooth one. In contradiction to the condition of presence of sand particles only, friction coefficient displayed by rough surface decreased with increasing tiles thickness.
Rough surfaces rubber tiles filled by polyurethane showed higher friction coefficient than the smooth ones at dry sliding. Friction coefficient increased as polyurethane content increased up to 20 wt. %. Further polyurethane increase had insignificant effect on friction coefficient. Friction coefficient drastically decreased with increasing polyurethane content for sliding against water lubricated tested tiles. Detergent lubricated surfaces displayed higher friction coefficient for smooth rubber. As the polyurethane content of the rubber tiles increased friction coefficient decreased. In the presence of sand particles, friction coefficient significantly increased for the both smooth and rough surfaces. Rough surfaces displayed higher friction values than smooth ones. Finally, drastic friction decrease for smooth surface was noticed for smooth tested rubber in the presence of water contaminated by sand particles.