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• Oxidative aging promoted and further stabilized asphaltene aggregation. • The driving force for aggregation was dispersion between the fused aromatic cores. • All additives reduced asphaltene aggregation and improved orientational randomness. • TBC exhibited the highest potential due to spatial distribution of four polar sites. Economic and environmental sustainability has been a significant stimulus to the use of recycled asphalt materials in the pavement industry. In this practice, rejuvenators are usually required to treat the oxidized asphalts with the aim to restore the physical properties and engineering performance. A critical function required for rejuvenators is that they can deagglomerate the asphaltene aggregates by effectively interacting with them. This study employed the techniques of molecular dynamics simulations and quantum chemical calculations, and investigated the impacts of oxidation on asphaltenes and the deagglomerating potential of three selected additives with different molecular structures and polarities, i.e., tributyl citrate (TBC), limonene, and myristamide. Analyses based on the aggregation number, orientational order parameter, and decomposition of the interaction energy indicated that oxidation strengthened the binding between the asphaltenes and thus promoted their aggregation behaviors. Among the three additives, TBC exhibited the highest rejuvenating effectiveness as it restrained the formation of large asphaltene aggregates and improved the orientational randomness of the aromatic cores. This capability was attributed to the highest number of polar sites in TBC and its three-dimensional spatial structure, which enhanced the compatibility and interactions with the aged asphaltenes. Based on the independent gradient model (IGM) method, the asphaltene aggregation is driven by the π-π interactions dominated by dispersion forces between the fused aromatic cores. The additives weakened the asphaltene interactions to different degrees, but the reversing effects were limited compared to the unaged state. [ABSTRACT FROM AUTHOR]

• A comprehensive evaluation method was proposed for the interfacial characterization. • A clear boundary was noted between melamine formaldehyde (MF) and the asphalts. • MF achieved better blending with the neat asphalt than with the polymer modified. • Addition of MF enhanced the diffusion of all components in both asphalts. Various microencapsulation technologies involving different shell and core materials have been proposed in the literature for improving the asphalt mixture performance. The interfacial characteristics including adhesion between the microcapsule shell and asphalt largely determines the synergistic rheology of the blend. This study evaluated the impacts of melamine formaldehyde (MF) resin as the shell material on the interface and bulk properties of a neat and styrene–butadienestyrene (SBS) modified asphalt binders using the techniques of scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and molecular dynamics (MD) simulation. The clear interface without voids or cracks revealed in the SEM images suggested good adhesion between MF and both asphalts. Satisfactory interfacial binding was also suggested in the FT-IT results. The absorption peak strength of the neat asphalt was higher than that of SBS modified asphalt, and the binding of MF with neat asphalt was stronger than with the modified. The modified asphalt exhibited a slightly lower compatibility due to the high difference in the solubility parameter between SBS and MF, 9.783(J/cm−3)0.5. Introduction of MF promoted self-association of the asphaltenes and enhanced the diffusion of all the four fractions in both asphalt systems. Diffusion of the asphaltenes in the neat and modified asphalts saw the highest enhancement, which was increased to 5.3915 and 3.7893 (10-10m2s−1), respectively. Increase in diffusion coefficient was attributed to the high polarity and mobility of the MF molecules. [ABSTRACT FROM AUTHOR]