ABSTRACT
Hot-mix asphalt (HMA) mixtures consist of three phases - aggregate, asphalt binder (mastic) and air voids - and generally can be considered as two-layered composite systems with aggregates dispersed in the asphalt matrix. Due to the nature of high inhomogeneity between aggregate and asphalt binder, significant stress and strain concentration occurs at the interface between the two phases, which causes adverse effects to HMA mixtures and potentially contributes to pavement distresses/failure.

This paper presents a novel idea to mitigate the stress and strain concentration and thus to improve the HMA mixture performance by introducing an intermediate layer between the aggregate and the asphalt binder in the HMA mixture. Microstructural analyses and laboratory experiments of the three-layered system were used to validate the idea.