Rutting Mechanical Tests for Balanced Design of Airfield Asphalt Mixtures

The Federal Aviation Administration (FAA) is investigating the development of a balanced mix design (BMD) framework with rutting and cracking laboratory mechanical tests for airfield asphalt concrete (AC) mixtures. This project specifically focuses on the rutting aspect of the FAA BMD framework, by establishing proper rutting test protocols and deriving relevant criteria for four laboratory rutting test methods. The manuscript presented the experimental plan data including laboratory and plant produced samples of several airfield mixtures at two air voids (AV) levels. Robust trends were found amongst different rutting tests, whereas for the Hamburg wheel track test (HWTT), the data were significantly influenced by the variability of the rut depth with stripping failure, especially in the case of cut specimens. Thus, additional parameters from the HWTT that could isolate the stripping failure from the mixture rutting characterization were investigated in this study. Based on the developed regression models and statistical analyses, the research team was able to derive initial criteria for the explored rutting tests based on the current FAA specification of maximum 10 mm asphalt pavement analyzer (APA) 250 psi/250 lb rut depth after 4,000 cycles.