Modelling the influence of capsules on the behaviour of asphalt mixtures

Abstract

Over the years, different methodologies, such as encapsulated rejuvenators, have been investigated to extend the service life of roads. However, these elements may impact the mechanical performance of asphalt mixtures, and accurately assessing their effects through experimental methods remains challenging, especially when isolating their influence from rejuvenator release. This study adopts the VirtualPM3DLab discrete-based model to evaluate the effect of capsules on the stiffness behaviour and tensile strength of asphalt mixtures. Mixtures incorporating different capsule contents (0.30 and 0.75 wt.%) were subjected to dynamic tension-compression and monotonic tensile tests. The results show that the impact on the stiffness modulus progressively increases with capsule content, reaching reductions between 4.3% and 8.7%, while the phase angle remains unaffected. Regarding tensile strength, the presence of capsules has a limited influence on the peak stress, which decreases from 3.80 MPa to 3.74 MPa (1.6%) and 3.57 MPa (6.1%) for the respective capsule ratios. The overall post-peak predictions across all scenarios follow a similar trend. In all scenarios, the majority of broken contacts are concentrated in the notch tip zone, consistent with experimental results reported for these materials. Broken contacts associated with capsules are mostly located in this region, which may facilitate the self-healing process once rejuvenator release is included in future simulations. The evaluated contents can, therefore, be safely adopted without significantly compromising the overall performance of asphalt mixtures.