Influence of Mineral Composition on Nano-Interfacial Adhesion of Asphalt Mixtures Exposed to Chloride Salt Erosion

As a common pavement deicing salt, sodium chloride has adverse effects on asphalt pavement. In this study, molecular modeling methods were used to analyze the effects of mineral composition and chloride salt erosion on the interfacial adhesion properties of asphalt-aggregate composites. Four representative asphalts (AAA-1, AAK-1, AAM-1, and AAF-1), three representative minerals (α-quartz, calcium carbonate, and alumina), and sodium chloride solutions were selected to model the asphalt-aggregate composites exposed to chloride salt erosion. The effects of asphalt type, sodium chloride concentration and erosion temperature on the interface adhesion of the asphalt mixture were considered. The chloride salt erosion resistance of the SARA fractions and asphalt molecular structures were further analyzed. The simulation results indicate that the effect of chloride attack temperature on the interfacial adhesion performance is minor. The interfacial adhesion performance decreased with the increase of chloride salt concentration. Alkaline minerals are more susceptible to the attack of chloride salts, followed by neutral and acidic minerals. Compared with dry conditions, the adhesion energies of resins and aromatics decreased most significantly in alkaline minerals, followed by neutral minerals, and the least decreased in acidic minerals exposed to chloride salt erosion. Asphalt molecules with more aromatic rings, shorter alkyl side chains, and stronger polarity have strong resistance to chloride salt erosion and can form strong adsorption with the active sites on the mineral surface. However, long-chain alkanes, asphalt molecules with fewer aromatic rings or longer alkyl side chains are difficult to resist the erosion of chloride salts.