Abstract:
Asphalt mixture faces damage due to vehicle speed, repeated loads, and ultraviolet
radiation over time, regardless of being a self-healing material. Induced healing mechanisms
are necessary to promote autonomous pavement recovery due to adverse in-service conditions,
and the capsule-asphalt mixture system incorporating low-viscosity oils (rejuvenators) has
shown to be a possible solution in laboratory tests. This study aims to numerically investigate
the effect of rejuvenator-modified mastic (activated capsules) on the stiffness properties of
asphalt mixtures within the discrete element method. A three-dimensional model previously
validated for rejuvenator-modified mastics with different rejuvenator-to-bitumen ratios (0, 2.5,
and 10 wt%) is adopted. A generalised Kelvin contact model represents the time-dependent
contacts, and its contact parameters define the rejuvenator amount in the mastic phase. The
analysis assesses the impact of the modified mastic amount and the rejuvenator-to-bitumen
ratio. Results show that the increasing modified mastic content progressively reduces the
mixture dynamic modulus. When the total mastic phase has rejuvenator-modified properties,
the mixture stiffness modulus significantly reduces, and the phase angle performs differently
from the expected (decrease with frequency) at a 10% rejuvenator-to-bitumen ratio due to the
excessively softened state, possibly compromising the pavement mechanical performance. For
a 0.30 wt% modified mastic ratio case adopting a local effect, the embedded elements do not
significantly influence the mixture rheological properties, especially the stiffness modulus,
which may be insufficient for self-healing purposes. Nevertheless, the negligible impact on the
phase angle highlights the potential of the rejuvenator-modified asphalt mixture across different
traffic and temperature conditions.