Characterization of interface morphology and its impact on interlayer bonding strength in double-layered asphalt systems

This study explored the effect of interface morphology on interlayer bonding in asphalt pavements, addressing existing challenges in its consistent characterization. The research aimed to develop a comprehensive indicator system for the characterization of interfacial morphology within double -layered asphalt constructs, thereby providing deeper insight into its impact on bonding strength. The methodology involved preparing specimens from three typical asphalt mixtures - dense -graded asphalt concrete (AC), stone mastic asphalt (SMA), and opengraded friction course (OGFC) - and analyzing their interlayer surfaces using a novel non-destructive technique alongside 3D laser scanning. This led to the identification of 32 morphological indicators across two-dimensional (2D) and three-dimensional (3D) domains. The findings revealed a significant correlation between these indicators and interlayer shear strength, establishing a robust framework for linking interface morphology with interface bonding properties. The study highlights the relative stability of the lower interlayer surface's morphology compared to the variability observed in the upper surface, attributed to differences in grain size distribution and skeleton. This variability significantly influenced the morphological reconstruction of the lower surface. Through the application of the M(P) characterization method, critical morphological indicators that exhibit a strong association with interlayer shear bonding were identified, enhancing the understanding of the factors influencing bonding efficacy in asphalt pavement layers.