Evaluating the fatigue characteristics and healing potential of asphalt binder modified with Sasobit® and polymers using linear amplitude sweep test

Abstract Sasobit® can be used not only as a warm mix additive in asphalt mixtures but also to further modify highly viscous polymer-modified asphalt (PMA) to achieve viscosity reduction, energy consumption reduction, and environmentally friendly engineering purposes. This paper demonstrates innovative research to evaluate several properties of asphalt binders modified with Sasobit® and polymers, including the exploration of the modification mechanism, fatigue damage characteristics, and healing potential at intermediate temperatures. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were conducted to explore the effectiveness of Sasobit® on the crystallization performance and chemical structure of styrene–butadienestyrene-modified asphalt (SBSMA), crumb rubber-modified asphalt (CRMA), and SBS/crumb rubber composite modified asphalt (SBS + CRMA). The accelerated fatigue approach, the linear amplitude sweep (LAS) test, was adopted to develop fatigue damage evolution of the Sasobit®/polymer-modified binders. A fatigue failure definition and the corresponding failure criteria based on the pseudo-strain energy (PSE) approach were adopted under the framework of the viscoelastic continuum damage (VECD) theoretical model. Subsequently, a healing process was extended. The LAS-based healing (LASH) step was introduced to assess the effectiveness of Sasobit® on the healing potential and fatigue life of the PMA. The XRD results suggested that Sasobit® weakened the crystallization effect of the PMA to some extent. Sasobit® affected the absorption of the polymers into the lighter components of the binder without creating new chemical components. The Sasobit® additives significantly raised the potential of PMA samples to resist fatigue failure. The LASH test results illustrated that Sasobit® increased the healing capacities of SBSMA and CRMA, but decreased the healing potential of SBS + CRMA. Furthermore, compared to the virgin binder, the Sasobit®/polymer-modified binder exhibited a weakened capacity to resist fatigue damage after short-term aging but a strengthened capability after appropriate long-term ultraviolet aging.