## 1 Introduction  
For the past two decades, researchers have been intensively developing self-healing asphalt technology as a cheaper, safer and more sustainable method of maintaining and repairing asphalt roads [1, 2, 3, 4]. The idea of the self-healing road stemmed from the concept of the \"forever open road\", motivated by the need to avoid the traffic disruption and associated risk of accidents caused by road maintenance activities on busy roads. The challenges for the road industry are to improve road material performance (make roads more durable), improve the sustainability of road construction methods (by introducing green technology) and improve the safety of the roads for both road users and road construction workers [5; 6; 7]. Self-healing asphalt technology has the potential to address several of the technical, economic, environmental and safety challenges currently facing the road industry. For example, self-healing asphalt technology has the potential to reduce the need for maintenance-related road closures, thereby reducing the risk to road maintenance workers, while simultaneously reducing the environmental impact of road construction and maintenance. It is estimated that self-healing asphalt technology could reduce energy consumption and CO\({}_{2}\) emissions by 30% over the lifetime of a road [8]. To date, researchers have tested three extrinsic self-healing methods for asphalt pavements, which are [1]: induction heating [1; 9; 10; 11; 12], microwave heating [4; 13; 14], rejuvenation (rejuvenator encapsulation) [15; 16; 17; 18; 2]. The rejuvenator encapsulation approach represents a more favourable method of asphalt self-healing as it is a passive healing system and does not require external action in order to initiate healing. The rejuvenation enables the aged bitumen to return to its original chemical, physical and mechanical properties. However, there are limitations with this method of self-healing because the healing rate is slow and healing efficiency low [2; 18]. Researchers have demonstrated that the induction and microwave heating methods are efficient methods for healing asphalt damage (3 to 5 min) in comparison to rejuvenation [2; 19]. However, a challenge with both methods is that the heating process (both induction and microwave) ages the bitumen, causing binder brittleness and the premature failure of the asphalt [9; 20]. Hybrid self-healing systems provide a solution to the challenges associated with induction, microwave and encapsulated rejuvenation. The hybrid self-healing technology combines induction heating and encapsulated rejuvenation [2]. In this process, induction heating is used to repair the asphalt damage (and the cracks), while rejuvenation is used to replenish the aged asphalt binder (bitumen). [PERSON] et al. [2] demonstrated that a hybrid healing system improves healing efficiency allowing for rapid damage repair and a simultaneous rejuvenation of the aged asphalt. However, a challenge with this approach is that the bituminous mix must be adjusted to accommodate both capsules and steel fibres. A solution to this challenge lies in combining the induction and rejuvenation into one product. [PERSON] et al. [4; 21] developed calcium alginate/nano-Fe\({}_{3}\)O\({}_{4}\) composite capsules for controlled rejuvenator oil release using microwave heating. [PERSON] et al. showed that the capsules demonstrated superior levels of healing with microwave heating due to the combined effect of thermal induction and rejuvenator healing. [PERSON] et al. showed that hybrid Fe\({}_{3}\)O\({}_{4}\)-calcium alginate capsules encapsulating a rejuvenator have a higher self-healing capacity (8.6%) when compared to the mix containing pure calcium alginate capsules encapsulating a rejuvenator and 19.3% in comparison to a standard asphalt mix. The asphalt mix containing 2% of the capsules achieved up to 87.2% healing after 40 s of healing time. The author ([PERSON] et al.