Ultraviolet (UV), light-activated, self-healing polymers are an emerging technology that was proposed to enhance the elastic behavior of asphalt binder, while improving its self-healing properties. The objective of this study was to evaluate the effects of self-healing polymer on the rheological properties of binder blends prepared with or without recycled asphalt materials. Binder blends were prepared with two different binders (PG 67-22 and PG 70-22M), with or without recycled asphalt materials, and 5% self-healing polymer (Oxetane-substituted Chitosan-Polyurethane). High-Pressure Gel Permeation Chromatography (HP-GPC) results showed an increase in High Molecular Weight (HMW) components in the binder with an increase in stiffness through the addition of recycled materials. A further increase was observed with the addition of self-healing polymer. Fourier Transform Infrared Spectroscopy (FTIR) confirmed HighPressure Gel Permeation Chromatography (HP-GPC) results with an increase in the carbonyl index. Furthermore, the addition of recycled materials led to an increase in the high-temperature grade and the low-temperature grade of the binder blends, while the self-healing polymer did not have a significant effect on the PG-grade. Overall, the addition of self-healing polymer led to an increase in stiffness and an improvement in the rutting performance, while it did not have a positive effect on low-temperature cracking performance. For unmodified binder (PG 67-22), self-healing polymer incorporation improved the elastic and fatigue cracking properties of the binder. However, when it was added to a polymermodified binder (PG 70-22M) and/or binder blends containing recycled asphalt materials, the potential of this material was low to negative on the low temperature and fatigue cracking performances.

Introduction

Asphalt binder is a viscoelastic material with self-healing abilities, which can restore its original properties by healing the micro-cracks and providing an asphalt mixture with higher durability. Yet, the rate of asphalt mixture’s crack healing process is slow for conventional asphalt binders at ambient temperature and under continuous loading [1]. On the other hand, the application of recycled asphalt materials such as Reclaimed Asphalt Pavement (RAP) and Recycled Asphalt Shingle (RAS) has received considerable attention due to its economic and environmental advantages. Various studies have been conducted in recent years with the aim to produce asphalt mixtures with high percentages or even 100% of recycled materials [2–۵]. Even with these advantages, the use of high content of recycled asphalt materials is challenging as the recycled binder is subjected to oxidation and aging during its service life. A severely aged binder is hardened and brittle, and as a result, it may increase the cracking susceptibility of the newly constructed mixture. In addition, the increase in the binder’s viscosity and the loss of relaxation can negatively affect the selfhealing properties of the binder, possibly causing premature failure of the pavement.