Rheological Properties and Anti-Icing Performance of Asphalt Modified with Hydrophobic and Salt-Storage Components

Hydrophobic and salt-storage functionalization can impart anti-icing capability to asphalt, but the associated changes in rheological behavior should be evaluated concurrently. In this study, silica aerogel and potassium acetate-loaded diatomite were incorporated as hydrophobic and salt-storage components, respectively. Contact angle and leachate conductivity were used to characterize surface wettability and ion-release response, while temperature sweep, frequency sweep, multiple-stress creep and recovery, bending-beam rheometer, and linear amplitude sweep tests were conducted to evaluate rheological performance. A compromise formulation was subsequently selected using multi-objective evaluation and the response surface methodology. The hydrophobic component increased the contact angle of asphalt, whereas the salt-storage component generated a time-dependent aqueous ion-release response. Composite modification improved high-temperature deformation resistance but increased low-temperature creep stiffness and reduced stress-relaxation capacity and fatigue life, indicating a clear rheological trade-off associated with functionalization. The selected formulation contained an 8% hydrophobic component and a 14.6% salt-storage component. At the mixture scale, this formulation reduced ice accumulation by 48.3%, lowered the freezing temperature of a 1 mm water film by approximately 2.8 °C, and decreased the apparent ice–pavement shear strength at −10 °C from 0.71 to 0.45 MPa relative to the control. These results indicate that hydrophobic and salt-storage components contribute differently to anti-icing behavior while jointly altering the rheological response of asphalt.