Establishing Indicators and an Analytic Method for Moisture Susceptibility and Rutting Resistance Evaluation Using a Hamburg Wheel Tracking Test

The Hamburg wheel tracking test (HWTT) is widely used to evaluate the performance of asphalt mixtures. According to HWTT specifications, the stripping inflection point (SIP) and the rut depth at a certain number of load cycles are two common indicators for evaluating the moisture susceptibility and rutting resistance of asphalt mixtures, respectively. Although these indicators have been used extensively by several transportation institutions, the reliability and stability in evaluating asphalt mixture behaviors of these indicators have been questioned. To more effectively evaluate the performance of asphalt mixture in the HWTT, this study introduces a novel method of analysis for the HWTT and novel indicators of rutting resistance and moisture susceptibility. The proposed method and indicators were employed to analyze the HWTT results of 14 field core specimens, and the proposed indicators were compared with conventional HWTT indicators to assess their capability of distinction between asphalt mixtures with different performance behaviors in the HWTT. The results indicate that the conventional HWTT indicators cannot effectively evaluate the asphalt mixtures with different performance in the HWTT. By contrast, the proposed analytic method and indicators have significant advantages to effectively evaluate and distinguish the rutting resistance and moisture susceptibility of asphalt mixtures.