A Novel Spore-Based System with Rejuvenator Controlled Release for the Self-healing of Bituminous Materials

Self-healing bituminous materials by adaptive encapsulated rejuvenators system is a hot topic within road materials. For the first time, this work explores the natural spores for the encapsulation of rejuvenators as a novel controlled release system to promote the self-healing capability in aged bituminous materials. Treated spores were obtained from natural spores by chemical processes. To synthesize spore-based microcapsules, firstly, spores were defatted, and then the protein and cellulosic materials were removed. Spores were processed, and sunflower oil as a rejuvenator was encapsulated inside spore microcavities by encapsulating passive and vacuum loading technologies. Physicochemical and microstructural properties of the natural spore formulations were evaluated. Changes in the composition of the spores among the process were studied by FTIR spectroscopy. The microstructure analysis showed that the spores after treatment were empty, showing the complete removal of all contents inside, keeping intact microstructure, and providing large cavities for molecular loading. Furthermore, sunflower oil encapsulation efficiency into the spore cavities was considerably higher with vacuum loading than by the passive loading process. The controlled release mechanism and the healing efficiency of encapsulated rejuvenators in the spore capsules were also quantified. It was proved that the proposed approach was able to control the release of the rejuvenator with an attractive biomaterial possessing a very strong structure. The main results provide the basis for further exploration into the encapsulation of rejuvenators in natural plant spores as a promising novel controlled release spore-based system for the self-healing of bituminous materials.