Accelerated Pavement Testing and Gradation-Based Performance Evaluation Method

Particle size distribution is a critical property that greatly influences an asphalt mixture's resistance to permanent deformation and cracking as well as a mixture's workability, permeability, and durability. The Superpave® mix design method attempts to address some of these issues by requiring that an aggregate gradation pass within control points. The control points concern: (a) the top size of the aggregate, (b) the relative proportion of coarse and fine aggregate, and (c) the dust proportion. Little additional guidance is given about suitable aggregate gradations. Some blends may pass the required Superpave criteria but perform poorly. A new theoretical approach for evaluation and specification of aggregate gradations was recently developed in Florida. The approach provides a framework to ensure that the resulting mixtures will have sufficient aggregate interlock to resist permanent deformation. Therefore, this method might be used at the mix design phase to assess the field performance of an asphalt mixture on the basis of aggregate gradation. A study was conducted to assess the appropriateness of, and to validate, this proposed approach through use of a controlled accelerated pavement testing experiment. The aggregate-based performance evaluation method is described, as are the subsequent experimental validation efforts and findings of the accelerated pavement testing.