Developing Representative Test Specimen Conditions for Rutting Mechanical Test Methods of Airfield Pavements

Abstract

The Federal Aviation Administration (FAA) is considering implementation of a balanced mix design (BMD) method for asphalt concrete (AC) of airfield pavements in a future specification update. One of the key elements toward implementing BMD, is setting adequate conditions for laboratory mechanical testing that best simulate actual field conditions. In this study, representative air void (AV) levels were identified for laboratory mechanical testing by analyzing quality control (QC) data of plant-mixed laboratory-compacted (PMLC) samples along with in-place density measurements for multiple existing airfield pavements. The laboratory compaction effort in the Superpave gyratory compactor (SGC) required to reach the recommended AV levels was evaluated for different specimen heights. The specimen height and AV level were then experimentally verified with the Ideal Rutting test (ASTM D8360-22) for these airfield mixtures. Based on analysis of field density, laboratory compaction effort, and mechanical test data, it was recommended to test 62 mm thick gyratory specimens at 7 ± 0.5% AV (directly molded) or at 5 ± 0.5% AV (after cutting), which should help capture the different aspects of the asphalt mixture’s resistance to rutting with reference to aggregate skeleton and binder properties.