Evaluation of hollow-fibers encapsulating a rejuvenator in asphalt binders with recycled asphalt shingles

Self-healing products such as hollow-fibers filled with an asphalt rejuvenator present an emerging technology that aims to enhance an asphalt mixture’s resistance to cracking damage. The objective of this study was to develop a fiber synthesis procedure to prepare sodium-alginate fibers containing an asphalt rejuvenator. An optimization process was conducted to identify the most suitable hollow-fibers for asphalt pavement applications by varying production parameters and testing the thermal stability and tensile strength of the different fibers. Furthermore, the effects of adding the developed fibers on the rheological properties of asphalt binder blends containing Post-Consumer Waste Shingles (PCWS) extracted binder was evaluated using Superpave Performance Grading (PG), Multiple Stress Creep Recovery (MSCR) test, and frequency sweep test. Based on the optimization of the fiber preparation procedure, it was observed that the prepared fibers had adequate thermal stability and tensile strength to resist typical compaction operations and mixing temperature during asphalt mix production processes. PG grading test results showed improvement at both high and low temperatures with the addition of the fibers compared to the asphalt binder blends with PCWS and no fibers. In addition, low-temperature test results showed a reduction in the stiffness of the blends with fibers compared to the virgin binders (i.e., PG 64-22 and PG 70-22). An improvement in the viscoelastic behavior of the asphalt blends with fibers was also observed in the MSCR test results with an increase in the percentage of recovery. As a result, the addition of hollow fibers to the unmodified binder with a rejuvenator as the core material led to an enhancement in the fatigue performance and an improvement in the viscoelastic behavior of the asphalt blends