Effect of fine particles on road skid resistance

8th Symposium on Pavement Surface Characteristics: SURF 2018 - Vehicle to Road Connectivity, BRISBANE, AUSTRALIE, 02-/05/2018 - 04/05/2018Fine particles originated from road and tires debris or traffic and industry emissions can be at the origin of some safety-related issues such as accidents at the first rain after a long dry period or seasonal variations of skid resistance. This paper presents a laboratory study reproducing under controlled conditions the process of particles' buildup and washing by runoff water. Surfaces composed of rough and worn aggregates are studied. The test protocol is described. Friction is measured by means of the British Pendulum. On a surface initially covered with particles, dry and wet tests are performed. Results show that on a contaminated surface, the friction coefficient drops significantly, compared to a clean state, and then increases. Mechanisms related respectively to dry and wet lubrications are presented. In parallel, mass of particles are monitored. It was found that friction and mass of particles evolves similarly but in opposite directions. Discussions are made in terms of the effect of particles' size and surface's microtexture