The intrinsic ability of asphalt pavement to undergo self-healing is not sufficient enough to effectively repair fractures resulting from a range of variables, including traffic load, asphalt aging and weather conditions. Consequently, the field of self-healing technology is focused on advancing crack repair techniques by employing microwave and induction heating and encapsulation amongst other healing procedures. These approaches make use of a range of additives, including waste materials and polymers, to facilitate the healing process. The present paper provides an in-depth review of self-healing technologies used for asphalt pavements, this including their conceptualization, development, application and the methods used to evaluate its performance. The self-healing capacity of materials can be influenced by various parameters including humidity, molecular diffusion, induction conditions, temperature and time. As such, treatments have the potential to enhance self-healing capacity, but with varying degrees of success depending on the specific evaluation indicator and healing situation. By examining international research, this review will also draw attention to the global relevance of the applicability of asphalt self-healing techniques used to enhance the durability and sustainability of transportation infrastructures worldwide. This paper therefore, serves as a valuable resource for researchers, practitioners and policymakers engaged in the pursuit of innovative solutions for resilient and cost-effective pavement systems on an international scale. This review also proposes prospective pathways for further study that will serve as a basis for future development of the industry.

The presence of filler in asphalt concrete may improve the properties of the mixture. This study investigates the mechanical and volumetric properties of such a mixture using walnut shell ash as a filler in various replacement ratios. The mixtures were mixed with various proportions of limestone (0%, 10%, 20%, 30%, 40%, 50%, 60%, 80%, and 100%) in addition to WSA as a replacement filler. Tests were subsequently carried out, including tests of Marshall’s stability and flow, voids in mineral aggregates, air voids, and theoretical maximum specific gravity. The results revealed that increasing the replacement percentage resulted in a considerable improvement in the performance of the asphalt–concrete mixtures. The results revealed that the mixture with a 60% replacement ratio achieved the best Marshall stability, achieving an improvement of 15.02% compared to the conventional sample, alongside good flow properties. This improvement was accompanied by high conformity with the other physical properties of the asphalt mixture, including a 3.55% air void percentage, which is within the permissible limits for the surface layer, as well as a 21.80% increase in the percentage of voids in the mineral aggregate, which is considered an ideal value. These results paved the way for further study and adjustments to other requirements of the asphalt mixture, as there were no issues with the availability or production costs of the filler material, given the abundance of raw materials. However, it is important to note that, as is evident from the results, a complete 100% replacement led to undesirable outcomes, resulting in a 10.68% decrease in Marshall strength compared to that of the conventional sample. This decrease indicates that the mixture was unable to provide its most important property. Although improving the other properties with complete replacement is not beneficial, a detailed investigation into this ineffective percentage revealed that, according to the results, the ideal replacement ratio is 60% walnut shells and 40% limestone, which results in optimal performance.