Recent advances in calcium alginate hydrogels encapsulating rejuvenator for asphalt self-healing

The inherent self-healing ability of asphalt is insufficient and fails to timely repair the cracks due to the combined effect of temperature variation, air oxidation, ultraviolet exposure and traffic loading. Rejuvenator encapsulation based on self-healing asphalt is a green sustainable preventive maintenance technology for asphalt pavement. During the last decade, rejuvenator encapsulation for asphalt self-healing has been a research hotspot and calcium alginate hydrogels encapsulating rejuvenator is a promising self-healing technology. Hence, this review sheds light on the recent advances of calcium alginate hydrogels encapsulating asphalt rejuvenator including self-healing capsules and fibers. The synthesis methods of calcium alginate capsules and fibers containing rejuvenator were elaborately introduced, and their surface morphology, interior structure, mechanical strength, thermal stability, rejuvenator content, distribution and survival in asphalt materials were systematically analyzed. Besides, the effect of capsules and fiber on the mechanical property and pavement performance of asphalt concrete were explored. Additionally, a comprehensive review about the effect of calcium alginate capsules and fibers on self-healing ability of asphalt materials were presented, and the rejuvenator release mechanism and release ratio of them in asphalt mixtures were expounded. In a nutshell, this review aims at highlighting the current research achievements on alginate capsules and fibers containing rejuvenator in asphalt materials, and inspiring enhanced self-healing methods for smart and sustainable maintenance of asphalt pavement.