Molecular dynamics simulation to study the rejuvenation mechanism of rejuvenators in aged asphalt

Rejuvenators are normally applied to guarantee the overall properties when Reclaimed Asphalt Pavement (RAP) is used. However, there are few atomic-scale interpretations on the rejuvenating mechanism of rejuvenator in RAP. This study focuses on the atomic modeling of rejuvenation behavior of oxidized asphalt. Three types of asphalt models (virgin, aged, and rejuvenated asphalt) were constructed respectively for comparative analyses of thermodynamics, glass transition behavior, free volume, self-diffusion, and atomic structures. Results denote a 4.43% increment of free volume and an 11.82 °C decrease of glass transition temperature in aged asphalt is observed after blending with 10% rejuvenators. Rejuvenators increase the cohesion of RAP binder to improve its cracking resistance. A dense and parallelly stacked structure of asphaltene is formed after oxidative aging. The introduction of rejuvenators plays the role of de-agglomeration, reversing the negative effects of aging to restore the microstructure of binder thereby recovering part of its properties.