Assessment of skid resistance using DFTester and CTMeter

Abstract

Skid resistance is related to pavement surface texture which include the wavelength ranges described by microtexture and macrotexture. Microtexture, with wavelengths less than 0.5 mm, depends on the surfaces of coarse aggregate particles, fine aggregate in asphalt mixture. It is associated with good skid resistance on wet roads. Macrotexture is depend on asphalt mixture properties (shape, size, and gradation of aggregate) and has an effect on skid resistance especially at high vehicle speed. In this paper skid resistance of different pavement surface textures based on IFI (International Friction Index) are compared. IFI (F60, Sp) was calculated using the MPD from the CTMeter (Circular Track Meter) measurement and the DF20 at a slip speed of 20 kph from the DFTester (Dynamic Friction Tester) measurement. Asphalt concrete and SMA pavements were measured in this study. In addition, the coefficient of friction F(S) was calculated at various slip speeds S. The influence of asphalt mixture composite, coarse aggregates polishing and site location (junction, straight and curve segments) were analyzed. As the result of the analysis it was found that at low speed pavements made of asphalt concrete had higher coefficient of friction than SMA pavements, while at high speeds SMA pavements had higher coefficient of friction than asphalt concrete pavements. Coefficient of friction have lower values on curves and junctions than on straight road segments on the same type of pavement. This may be valuable information for proper maintenance of existing pavements and on the stage of designing.