Interlocking characteristic and its correlation with interlayer shear strength in typical double-layered asphalt systems

Interlayer bonding is crucial to maintaining the structural integrity of asphalt pavement structures. Addressing a crucial research gap, this study uniquely investigated the impact of interface morphology on interlocking properties and interlayer shear strength in three typical double-layered asphalt systems: AC-13/AC-20, SMA-13/AC-20, and OGFC-13/AC-20. Through the innovative application of nondestructive separation technology and three-dimensional (3D) laser scanning, interface morphology characteristics were thoroughly analyzed. This approach enabled the detailed extraction of texture parameters, unveiling the complex relationship between interface morphology and interlayer bonding strength. Interface shear tests further assessed the difference in shear strength, revealing significant differences in texture characteristics influenced by the mineral size variance in the upper layer. This analysis led to the development of a predictive model for interlayer shear strength based on morphological characteristics, offering a new tool for approximating the shear bonding condition, despite challenges in capturing the complex interaction between interface morphology and interlocking effects. The comprehensive examination of 3D interface morphology, combined with the shear strength analysis, clarified the mechanisms of interlayer bonding in relation to interface morphology. This breakthrough provides essential insights into the role of interface morphology in bonding efficacy and represents a significant advancement in understanding of interlayer bonding mechanisms.