Moisture sensitivity of asphalt mastics with different fillers at the macro- and microscale

Moisture damage is one of the main distresses of asphalt pavement, and the design and evaluation of moisture damage resistance has always been an important task in the design of asphalt pavement materials. To analyze the water sensitivity of the mastic materials in asphalt mixtures, the rheological properties of different asphalt mastics were tested via dynamic shear rheology tests, including temperature sweep, frequency sweep, and linear amplitude sweep (LAS) tests, to characterize temperature-dependent viscoelastic behavior and intermediate-temperature fatigue resistance. The change in the free energy of the asphalt mastics under moisture damage conditions was investigated, the cohesive energy of the asphalt mastics was calculated via surface free energy theory, and the chemical changes in the different asphalt damage conditions were investigated via infrared spectroscopy. Moisture-induced changes in complex modulus and phase angle were most pronounced between 10 and 45 °C and became limited above 45 °C. After 168 h of immersion, the LAS fatigue life of SBS-modified asphalt at the 5.0% modulus-reduction criterion (N f5.0% ) decreased by approximately 59.1% relative to the dry state, whereas cement and antistripping-agent mastics retained more fatigue life. Prolonged immersion also reduced asphalt–filler interaction capacity, surface free energy, and cohesive energy. FTIR showed no new immersion-induced peaks but revealed qualitative changes in existing spectral profiles. Considered together with the rheological and cohesive-energy results, these observations indicate that the anti-stripping-agent mastic had the most favorable overall moisture resistance among the three mastics.