Comparison of Laboratory Wheel-Tracking Test Results with Wes Track Performance

Abstract

In 1990, members of FHWA participated with other industry and highway agencies in a European asphalt study tour to examine pavement technology. One of the technologies brought back from this tour was laboratory wheel-tracking devices. However, the ability of these devices to predict or rank field performance has been questioned. WesTrack provides a unique opportunity for comparing accelerated laboratory wheeltracking devices with full-scale pavement performance under controlled conditions. The three devices examined here are the asphalt pavement analyzer (APA), the French pavement rutting tester (FPRT), and the Hamburg wheel-tracking device (HWTD). WesTrack is a 2.9-km oval test track with each tangent consisting of 13- to 70-m sections. Samples for laboratory evaluation using three wheel-tracking devices were taken from the 5-m sampling segments of the rehabilitated sections: 10 sections placed in the summer of 1997. Based on the data and analyses in this study, the three laboratory devices examined satisfactorily correlate with the permanent deformation of the WesTrack sections studied. The correlations are 89.9, 83.4, and 90.4 percent for the APA, FPRT, and HWTD, respectively. The devices, although not perfect in predicting or ranking section performance, did exhibit increased variability with poorer performance. This increased variability with mean permanent deformation or creep rate allows for a rational method to establish mixture design specifications for all three devices. The procedure exhibited here is flexible, allowing an agency to select the level of performance desired. The selection of an appropriate test temperature that reflects the in-service temperature at which the pavement will be expected to perform was found to be necessary as well.