Study on the Interfacial Thermodynamics‐Driven Curing Behavior, Phase Evolution, and Multi‐Scale Performance Correlation Mechanism of Epoxy Asphalt

Abstract

To overcome the challenges in understanding the complex curing and interfacial mechanisms of epoxy asphalt for high‐performance pavements, this study investigated performance evolution through the lens of interfacial energy. Unlike conventional research focusing on post‐cured properties, a high‐temperature pendant drop method was developed to directly measure the liquid‐phase surface free energy (SFE) during early curing. Combining viscosity analysis, in situ fluorescence microscopy, and nanoindentation, we explored the relationships among composition‐dependent liquid‐phase SFE, phase morphology, and multi‐scale mechanical properties. Results showed that increasing asphalt content triggered a sharp decline in SFE, which was accompanied by the phase structure transition from homogeneous encapsulation to a “sea–island” morphology. Strong correlations between SFE, reduced modulus ( R 2  = 0.997), and elongation at break indicated a close association between liquid‐phase surface energetic characteristics and subsequent mechanical responses. Within the material system investigated, an SFE range of 32–34 mN/m was associated with a relatively favorable balance between strength and ductility, suggesting a possible relationship between system polarity and phase transition behavior. This research provides an interfacial thermodynamic perspective for understanding the “curing–structure–performance” relationship and offers a reference for the formulation and performance optimization of high‐performance epoxy binders.