TIME-DEPENDENT SURFACE PROPERTIES OF ASPHALT FRICTION COURSES: EARLIER EXPERIMENTS BY A NEW ACCELERATED TEST

Pavement Management Systems need to estimate schedule and costs; as a result, it becomes more and more important the evaluation of friction and texture reduction in time for different conditions of traffic and weather. This can be done by suitable provisional models in order to analyse factors affecting wearing and their influence on surface performance. Full-scale experiments (often consistent and effective but expensive) or accelerated friction testing (often reliable, less expensive, with well-controlled boundary conditions) are so needed. This paper deals with the design and the carrying out of an experimental plan in order to realize low-cost information on friction and texture decrease as an effect of traffic. An apposite device has been recently designed and constructed at the DIIV Laboratory (Palermo University - Department of Road Infrastructures), by modifying a Wheel Track Machine for rutting tests. Authors present the results of the earlier experiments on friction reduction; time-friction and time-texture curves are analysed and interpreted. Friction is estimated in terms of British Pendulum Number while both micro- and macro-texture components are measured by a laser device.