Effects and mechanisms of different types of chloride salts on the adhesion properties of asphalt/recycled concrete aggregate interfaces

• The most critical interface damage is caused by NaCl solutions. • Surface disintegration occurs in mortar substrates due to chloride salt erosion. • The nanostructure within the asphalt undergoes changes due to chloride erosion. Interfacial damage induced by chloride de-icing agents constitutes a key factor in the insufficient durability of asphalt pavements. This study employs a combined approach of laboratory testing and molecular dynamics (MD) simulations to investigate the erosion mechanisms of different chloride salts at the interface between asphalt and recycled concrete aggregate. The study revealed that the degree of interfacial damage follows the descending order of NaCl, MgCl 2 , CaCl 2 , and H 2 O. At the microscale, the asphalt/limestone interface exhibits significantly superior erosion resistance compared to the asphalt/mortar interface. This is primarily attributed to the porous structure of aged mortar providing rapid diffusion pathways for the corrosive medium, accelerating asphalt film delamination and mortar matrix disintegration. Conversely, the dense crystalline structure of limestone forms an effective physical barrier. MD simulations further reveal that the corrosive medium alters the nanostructure of asphalt. Specifically, Na + introduces a significant quantity of interfacial water molecules via its hydration shell, leading to a marked reduction in the relative concentration of aromatics and resins at the interface. This induces interfacial adhesion failure. These findings provide theoretical insights for developing novel de-icing agents and optimizing pavement maintenance strategies.