Analytical Modeling of Three-Layered HMA Mixtures

Abstract

This paper presents the analytical modeling of three-layered hot mix asphalt (HMA) mixtures. Conventional HMA mixtures can be regarded as a two-layered composite with asphalt-coated aggregate particles dispersed in an equivalent medium. The three-layered HMA mixtures can be constructed by introducing an intermediate layer of stiff binder coated over coarse aggregates prior to mixing them with hot asphalt cement. Based on the equivalent medium theorem reported by Eshelby in 1957 in “The Determination of the Elastic Field of an Ellipsoidal Inclusion, and Related Problems,” HMA mixtures were treated as particulate-filled composite materials. Theoretical formulations of the composite modulus were developed and finite element analysis of stress concentration in the asphalt binder was conducted. To validate the analytical results, a three-layered HMA utilizing natural asphalt (gilsonite) as the intermediate layer was prepared and dynamic modulus and indirect tensile strength tests were conducted. The lab-scale tests agreed with the theoretical results and further ascertained the benefits of utilizing the three-layered structure in HMA mixtures.