Effects of polyacrylonitrile fibres and high content of RAP on mechanical properties of asphalt mixtures in binder and base layers

In this present study, the effects of polyacrylonitrile fibres and high content (50%) of Reclaimed Asphalt Pavement (RAP) on the mechanical properties of asphalt mixtures in binder and base layers were studied. This is the first time that the effect of high RAP content on the mechanical properties of fibre reinforced asphalt mixtures (FRAM) was evaluated, while the low temperature performance was not usually conducted in previous studies. Results indicated that the addition of polyacrylonitrile fibres worsens the moisture susceptibility resistance, but improves the rutting, stiffness properties, fatigue performances, and cumulative fatigue damage of the mixtures with and without RAP. No significant effects on the low temperature cracking resistance were found when fibre was used, while a remarkable improvement in the crack propagation resistance properties was observed. Therefore, the use of polyacrylonitrile fibres improves in general the mechanical responses of the mixture, especially in the stiffness response.