Interfacial adhesion analysis between granular-asphalt binder and granular-mastic systems

Asphalt mastic, comprising bituminous binder and mineral filler, is essential for cohesion among components in asphalt mixtures. The combination and interactions between these materials directly influence the mechanical performance and durability of asphalt pavements. However, the interfacial interaction between the mineral and the bituminous binder is not fully understood and insufficiently characterized, owing to the difficulty in adapting experimental techniques and measurement methods suitable for interfacial analysis. Three asphalt mastic mixtures with mineral additions were evaluated: one with 6 % gneissic filler; another with 6 % hydrated lime; and finally, a mixed condition containing 3 % of each. The samples were divided into two groups: (i) without prior conditioning with the mineral substrate and (ii) with prior conditioning, wherein the asphalt mastic was heated to 155 °C and the mineral substrate to 165 °C. For characterization, X-ray Diffraction, Scanning Electron Microscopy, Fourier Transform Infrared Spectroscopy, X-ray Photoelectron Spectroscopy, and goniometry techniques were used. The results showed that prior conditioning with the mineral substrate significantly affected the physicochemical properties of the asphalt mastic-mineral substrate interface. Specifically, variations in surface chemical composition and alterations in sample morphology were observed. Furthermore, surface free energy exhibited distinct interfacial values. This study contributes to the understanding of interface interactions between asphalt mastic and granular materials, offering potential for the development of predictive models aimed at material selection.