Doctor of Philosophy (PhD)


Construction Management

Document Type



Self-healing mechanisms, such as microcapsules or hollow-fibers, filled with an asphalt rejuvenator present an emerging technology that would enhance an asphalt mixture’s resistance to cracking damage caused by vehicular and environmental loading. The objectives of this study were to: (a) Evaluate the effects of asphalt rejuvenators on hot-mix asphalt mixtures in order to test its effects on the fundamental engineering properties of the mixtures at high and intermediate temperatures; (b) Develop a synthesis procedure for production of microcapsules and hollow-fibers containing an asphalt rejuvenator; (c) Evaluate the self-healing efficiency of double-walled microcapsules and hollow-fibers filled with an asphalt rejuvenator, through crack healing and stiffness recovery of damaged mixture specimens under two different curing conditions.

The core material for the self-healing mechanisms was selected by evaluating four different asphalt rejuvenator products through a set of laboratory tests to characterize the performance of asphalt mixtures against permanent deformation and fatigue cracking. Afterwards, the evaluated self-healing mechanisms were produced by modifying chemical synthesis procedures to develop double-walled microcapsules and hollow-fibers containing the selected rejuvenator product as core material. Furthermore, a self-healing experiment was designed to evaluate the rejuvenating and healing properties of the developed self-healing mechanisms.

The evaluation of HMA mixtures containing recycled materials showed that the rutting and cracking susceptibility increased with the addition of the evaluated asphalt rejuvenators. The activation of more binder from the recycled materials with the addition of asphalt rejuvenators was observed in the GPC test results as an increased in the asphaltenes-to-maltenes ratio was observed. The evaluation of self-healing microcapsules showed that the mixtures containing the produced microcapsules had a lower healing efficiency at both environmental curing conditions compared to the mixture with Rejuvn8. Also, an opposite relationship between healing recovery and stiffness recovery was observed as the mixture containing microcapsules had a better stiffness recovery at both environmental curing conditions as the mixture with Rejuvn8. The self-healing experiment conducted to evaluate the strength recovery of the produced fibers showed an enhancement at both room and high-temperature of mixtures prepared with unmodified binder containing recycled materials with the addition of fibers.



Committee Chair

Hassan, Marwa