Simple Robust Method for Analyzing Hamburg Wheel Tracking Test Data

Though the Hamburg wheel tracking test (HWTT) is adopted by AASHTO for characterizing both rutting and stripping performance of an asphalt concrete mixture, the final rut depth or rut depth at certain loading cycle is the most common reporting parameter that is used by most of the state agencies. The probable reason for this situation is the human subjectivity associated with American Association of State Highway and Transportation Officials (AASHTO) procedure. Rutting and stripping are characteristically two different types of damage evolved from two different damage mechanisms. The final rut depths of two different mixtures can result from two different combinations of rutting and stripping damages. Thus, the direct comparison of final rut depth between these two mixtures is impractical. Though there are some mathematical models proposed by researchers to overcome this limitation, this study found that these models have reliability and robustness issues. To this end, this study developed a simple, reliable, and robust method to analyze HWTT data by accurately differentiating the rutting and stripping damage contributions from the cumulative rut-depth plot. A total of 48 different mixtures' HWTT data were used to evaluate the accuracy of the method. The developed method is found to be more accurate and robust than the existing models.