Abstract
Hot-mix asphalt (HMA) laboratory mix design is intended to determine the proportion of aggregate and binder that, when mixed and compacted under a specified effort, will withstand anticipated loading conditions. Current mix design procedures that use the Superpave® gyratory compactor rely on the engineering properties and volumetrics of the compacted mixture to ensure reliable performance; however, a definitive performance test does not exist. The asphalt pavement analyzer (APA) was evaluated as a tool for assessing HMA mixtures designed to perform under high tire pressure aircraft following FAA specifications. The APA used in this study was specially designed to test simulated high tire pressures of 250 psi, which are becoming more common for aircraft. Thirty-three HMA mixtures were included in the study. Each was designed with the Superpave gyratory compactor, according to preliminary criteria being developed by FAA. The study included some mixtures that contain excessive percentages of natural sand and that do not meet FAA criteria. These mixtures were included to provide relative performance for mixtures expected to exhibit premature rutting. APA testing with the high tire pressure APA resulted in rapid failure of HMA specimens compared with traditional APA testing at lower pressures. Data were analyzed, with a focus on the provision of acceptance recommendations for mixtures to support high tire pressures. A preliminary 10-mm rut depth criterion after 4,000 load cycles is recommended.
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