Comparative Analysis of Empirical and Fundamental Tests for Rutting in Asphalt Mixtures

Abstract: Performance tests are central to the balanced mix design (BMD) methodology and the use of simple, practical, and performance-indicating tests is vital for the success of BMD implementation. The existence of such tests can help facilitate the implementation of BMD into practice. The purpose of this study was to explore the ability of simple, practical, yet empirical tests to capture the rutting potential of asphalt mixtures as quantified by the fundamental tests and mechanistic-empirical analysis. Furthermore, the study aimed to assess potential inherent relationships between individual testing protocols, encompassing both screening and fundamental tests. Additionally, it sought to examine the correlation between each testing protocol and mechanistic-empirical analysis outcomes. To that end, three empirical tests [the indirect tensile at high temperature (IDT-HT) test, the rapid rutting (RR) test, and the asphalt pavement analyzer (APA) test] were used alongside three fundamental tests [the dynamic modulus test, the stress sweep rutting (SSR) test, repeated load permanent deformation (RLPD) test].
Ten representative asphalt mixtures incorporating unmodified virgin binders designed to carry up to 10 million equivalent single axle loads, as per VDOT specifications, were included in this study. The sample collection and preparation process were divided into two phases. In Phase I, four laboratory-produced and laboratory-compacted asphalt mixtures were designed and produced. Phase II involved the collection and preparation of six plant-produced, laboratory-compacted samples. The results showed that the overall rutting potential of asphalt mixtures quantified by the IDT-HT, RR, and APA tests is in agreement with that of fundamental rutting tests and mechanistic-empirical analysis. Among the empirical tests, the IDT-HT test demonstrated the highest overall correlation with fundamental tests. Furthermore, the fundamental tests yielded similar results when assessing the overall rutting potential of asphalt mixtures. Notably, both empirical and fundamental test methods exhibited rutting performance trends that aligned well with mechanistic-empirical analysis outcomes. Expanding upon these laboratory findings, the research has advanced to include field evaluations that incorporate data from heavy vehicle simulator tests and in-service pavement monitoring.