The Effect of Additives on Water Vapor Condensation on Bituminous Surfaces

Ice formation and adhesion on bituminous asphalt concrete are responsible for many accidents in winter and have caused an overreliance on deicing treatments such as anti-icing chemicals, which are costly, environmentally damaging, and increase maintenance frequency. Bitumen is mainly a combination of various kinds of hydrocarbon-based chemicals and exhibits complex material behavior and properties. However, bitumen makes up only ca. 5 wt.% of the asphalt concrete mixture. Owing to its binder role and coating function of the aggregates, bulk mechanical properties and surface properties of the mixture are dominated by bitumen. In this study, we investigate the phenomenon of condensation from humid air and, eventually, ice formation from condensate on bitumen as the first step toward understanding the freezing of road surfaces. We report first results on these phenomena as they develop on various regions of the complex bitumen surface featuring different wettabilities due to their chemistry. Furthermore, in this study, we show the effect of different additives: polyethylene terephthalate (PET), polyamide (PA 66), polyacrylonitrile (PAN), and Sasobit wax on bitumen water affinity.