Application of rejuvenators to improve the rheological and mechanical properties of asphalt binders and mixtures: A review

The use of recycled materials such as Reclaimed Asphalt Pavement (RAP) and Recycled Asphalt Shingle (RAS) in asphalt pavements is a valuable approach to construct sustainable pavements and to preserve natural resources and energy. However, the use of high amounts of RAP and RAS can potentially cause durability-related distresses such as cracking and raveling due to the presence of severely aged asphalt binders. Rejuvenators have been widely used to overcome this issue and to mitigate the problems associated with the use of aged binders. They can improve the viscoelastic and rheological properties of asphalt mixtures containing RAP and RAS. Much has been learned about various types of rejuvenating agents, techniques to apply these agents, and challenges associated with their applications. This article reviews the literature on the applications of various types of rejuvenators in paving industry and their effects on the properties of the aged binders. The techniques for rejuvenating the aged asphalt binders and the mechanism of rejuvenation are also reviewed. Moreover, methods to determine the optimum rejuvenator content to achieve optimized mechanical and durability properties of the asphalt binders and mixtures are discussed. The findings in this research show that rejuvenators can be successfully used to restore the properties of the aged binders. It is hoped that this review will serve as a guidelines for pavement engineers to better design the asphalt mixtures containing rejuvenators. This review will also help scientists to find future avenues of research on the applications of rejuvenators in asphalt industry. (C) 2019 Elsevier Ltd. All rights reserved.