Laboratory test method for the prediction of the evolution of road-skid resistance with traffic

This paper presents a laboratory test method for the prediction of the skit-resistance evolution due to the traffic. This work has been carried out at LCPC since 2004 and aims at providing road engineers and managers with tools to optimize asphalt mixes and forecast the road maintenance. Results are first presented on the test method simulating the polishing process on road specimens. The so-called Wehner/Schulze (WS) polishing and friction machine is briefly described. The polishing procedure is given. Simulated friction-time curves are compared to actual data obtained from trafficked roads. This step validates the relevance of the test method regarding its capability to reproduce actual skid-resistance evolutions. Comparisons are then performed between friction-time curves of respectively asphalt- and aggregate specimens. This step is important since results show to that extent polishing tests on aggregates could be used to assess the behaviour of asphalt mixes. The relationship between WS and PSV tests for the aggregate component is also discussed. The last part of the paper deals with the polishing test duration (N) necessary to reach a given friction value, and its relationship with the traffic (T). It is shown that a linear relationship N = k.T is a good approximation. Values of the "k" factor are presented and discussed. Attempts to predict actual skid-resistance evolutions with traffic from Wehner/Schulze tests are presented