Gelation-Stabilized Functional Composite-Modified Bitumen for Anti-icing Purposes

Ionic salts as anti-icing agents have been extensively used to eliminate accumulation of ice on asphalt surfaces. However, salt can be easily removed by rain or automobiles and requires frequent application on roads. Besides this economic consideration, anti-icing agents compromise the mechanical properties of asphalt and have a negative impact on living organisms and the environment when used in large amounts. Incorporation of hydrophilic salts into bitumen, a hydrophobic asphalt binder, and controlled release of specific molecules from this hydrophobic medium can provide an effective solution for reducing ice formation on pavements. Bitumen has previously been modified by various polymers, including styrene-butadiene-styrene (SBS) for improved strength and thermomechanical properties. However, an anti-icing function was not considered in those previous designs. In a previous study, we developed a functional polymer composite consisting of potassium formate (HCOOK) salt pockets dissolved in a hydrophilic gel medium and dispersed in a hydrophobic SBS polymer matrix. Here, we developed an innovative method to obtain polymer composite-modified bitumen and investigated further the anti-icing properties of the functional bitumen. We improved incorporation of this polymer composite into bitumen and demonstrated proper distribution of the composite within bitumen through morphological and rheological analysis. We characterized the anti-icing properties of modified bitumen surfaces and demonstrated significant increases in freezing delay of composite-modified bitumen compared to base bitumen in a temperature- and humidity-controlled chamber. In addition, we characterized the release of HCOOK salt from polymer composite-modified bitumen and observed salt release within the range of 1.07-10.8% (w/w) in 67 days, depending on the composite content. The results demonstrate the potential of this polymer composite-modified bitumen for anti-icing functionality and for industrially relevant applications.