Effect of Aggregate Gradation on Performance of Asphalt Concrete Mixtures

Abstract

This paper investigates the process of selecting the aggregate gradation according to the Superpave mix design specifications and evaluates the volumetric properties and mechanical performance of mixtures with perturbed aggregate gradations. The mix design information and pavement materials for two typical Superpave mix designs with a 12.5-mm nominal maximum aggregate size were collected for this study. The volumetric properties of the mixtures were judged mainly by the voids in mineral aggregates, whereas the rutting potential and strength of the mixtures were assessed with the Hamburg wheel-tracking and indirect tension tests, respectively. Bailey ratios and corresponding acceptance criteria were used to evaluate the impact that aggregate gradation has on the engineering behavior of mixtures. Although design variables such as binder content and characteristics can be adjusted to improve the performance of mixtures, balanced volumetric and mechanical properties can be achieved by selecting the aggregate gradation in a rational manner.