Effects of tensile and compressive stresses on the surface morphology and microscopic adhesion properties of asphalt after chloride salt erosion

Document Type

Article

Publication Date

9-19-2026

Abstract

Chloride salt erosion coupled with traffic loading is considered one of the primary causes of early deterioration in asphalt pavements used in coastal highways, sea-crossing bridge deck pavements, and regions where deicing salts are extensively applied during winter. To investigate the evolution of adhesion behavior and surface morphology of asphalt after chloride salt erosion under tensile and compressive deformation, 70# base asphalt was selected in this study. Asphalt thin-film samples were immersed in sodium chloride solution with concentrations of 0%, 5%, 10%, and 15%, respectively. Atomic force microscopy (AFM) and molecular dynamics (MD) simulations were employed to analyze surface morphology, adhesion behavior, component diffusion, spatial distribution, and asphalt–aggregate interfacial adhesion energy. The results indicated that the characteristic bee-like structures on the asphalt surface could still be observed after chloride salt erosion; however, their size, boundary clarity, and spatial continuity changed significantly. The smooth surface regions increased, and localized areas with possible salt crystal deposition appeared under high-concentration conditions. The maximum adhesion force exhibited a non-monotonic response to NaCl concentration. Under tensile loading, the maximum adhesion force increased from approximately 125 nN before deformation to approximately 300 nN after deformation at a NaCl concentration of 10%. Under compressive loading, the corresponding value increased from approximately 136 nN to approximately 250 nN. In contrast, for the 15% NaCl compression group, the maximum adhesion force decreased from approximately 80 nN before deformation to 44 nN after deformation. The MD simulation results further demonstrated that chloride salt exposure affects the diffusion capability and spatial redistribution of asphalt components, resulting in a non-monotonic variation in interfacial adhesion energy that is generally consistent with the AFM observations. The findings indicate that the evolution of the microscale adhesion properties of asphalt under chloride-rich environments is jointly governed by component migration, salt-related deposition, localized hardening, and stress redistribution. This study provides fundamental insights into the durability evaluation of asphalt pavements exposed to salt attack and the design of salt-resistant asphalt materials.

Publication Title

Construction and Building Materials

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