## 4 Conclusions  
This paper evaluated alginate-based polynuclear capsules containing Waste Cooking Oil (WCO) as a promising encapsulated rejuvenator for microcrack self-healing in long-term aged bitumen. Based on the results, the following conclusions have been obtained:  
* The encapsulation process by simple extrusion-dripping yielded alginate-based WCO capsules with an adequate encapsulation efficiency and multicavity morphology for asphalt self-healing applications.
* WCO polynuclear capsules and their components presented a good thermal stability and physical-chemical properties. Creating results showed that encapsulation of the O/W emulsion should be addressed during the first 2 h.
* TGA and FTIR tests suggested that the encapsulation process leads to a thermally stable material with potential to be mixed with hot asphalt mixtures for asphalt healing purposes.
* Mechanical characterisation proved that alginate-based WCO capsules can break and partially release the encapsulated WCO oil through an external force trigger effect.
* It was proven through transient oil-bitumen diffusion tests that the encapsulated rejuvenating agent WCO can be diffused in long-term aged bitumen test samples, reducing their viscosity, and hence, healing microcracks present in the asphalt matrix.  
Future work of this research will include a comprehensive study to understand the effect of rejuvenating oil type (including Virgin Cooking Oil, Waste Cooking Oil, and Virgin Engine Oil) on the synthesis and properties of alginate-based polynuclear capsules  
Figure 6: **(a)** Experimental set-up to evaluate the crack-healing of WCO on a long-term aged bitumen sample; **(b–d)** Fluorescence microscopy images showing the microcrack closure over time using WCO as healing agent; **(e)** Results of healing efficiency and crack width measured on the long-term aged bitumen sample.  
for asphalt self-healing. An evaluation of the chemical changes associated with their incorporation into aged bitumen samples (SARA fractions analysis) must be considered.  
Conceptualisation, J.N.-C.; methodology, J.N.-C., J.L.C. and I.G.-T.; software, J.N.-C.; validation, J.N.-C. and I.G.-T.; formal analysis, J.N.-C., J.L.C. and L.E.A.-P.; investigation, J.N.-C., J.L.C. and I.G.-T.; resources, J.N.-C. and L.E.A.-P.; data curation, J.N.-C., J.L.C. and I.G.-T.; writing--original draft preparation, J.N.-C. and J.L.C.; writing--review and editing, J.N.-C., J.L.C., L.E.A.-P. and I.G.-T.; visualisation, J.N.-C. and J.L.C.; supervision, J.N.-C.; project administration, J.N.-C.; funding acquisition, J.N.-C. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Research and Development Agency (ANID) through the Research Projects FONDECYT 1190027, FONDEQUIP EQMI170077 and CONICYT PIA/Apoyo CCTE 170007.  
Not applicable.  
Second author wishes to thank the financial support given by the University of Bio-Bio for his internal PhD scholarship granted. The authors extend their gratitude to the former student [PERSON] from LabMAT and [PERSON] from CIPA-CONICYT Regional, for their technical support with some laboratory tests.  
The authors declare no conflict of interest.