Adhesion Evaluation of Aggregate–Asphalt System Based on Surface Energy

Considering the shortcomings of the traditional water boiling method, an evaluation method of aggregate-asphalt adhesion based on surface energy is proposed. The surface energy and adhesion work were analyzed, the effect of aggregate type and anti-stripping agent on the adhesion characteristics of the aggregate-asphalt system was analyzed, and the relationship between the apparent properties of aggregates and surface energy and its effect on adhesion was discussed. The correlation between the parameters using the improved water boiling method and the work of adhesion was investigated. The results show that the adhesion work index can distinguish the improvement effect of different anti-stripping measures, which can effectively evaluate the adhesion between asphalt and aggregate. The surface energy of alkaline aggregate limestone is greater than that of acidic aggregate granite. The effect of aggregate surface texture on aggregate-asphalt adhesion is greater than that of angularity and sphericity. The acidic aggregates have much more surface polarity than other ones. The dispersive components of the surface energy of asphalt are larger than the polar components, and the addition of an anti-stripping agent improves the surface energy of the matrix asphalt, which can effectively improve the adhesion of the asphalt-aggregate system. The improved water boiling method can effectively evaluate the adhesion between acidic aggregates and asphalt and has a good degree of discrimination.