Safety aspects on icy asphalt pavement in cold region through field investigations

It has been proved that ice shows different friction regimes. This work focuses on rubber friction on ice, a topic of great practical significance when it comes to grip of tires on icy road surfaces. Here the possibility of using Dynamic Friction Tester (DFT) for assessing skid resistance under icy condition is presented. The ice thickness was then controlled by the volume of the freezing water spraying on a consistent area so that the surfaces were characterized by different degrees of ice coverage. As a consequence, eight surface conditions were considered and tests were conducted at different temperatures ranging from - 5 to - 20 degrees C. In addition, aiming at the analysis of the changes due to wear of ice, several cycles of measurements were conducted and the effect of the temperature was investigated. The results showed that the dynamic friction coefficient reached steady state on icy surfaces during decelerating process, which is much lower than other conditions. Moreover, the data reached a low point at -14 degrees C, resulting from the thermal equilibrium between the dissipation of frictional heat during the contact and the melting of the ice layer between two consecutive passages.