Investigating Asphalt Self-Healing with Colorless Binder and Pigmented Rejuvenator
Tiago Letras Ribeiro, Ana Cristina Freire, M. Sá da Costa, João P. Canejo, Vinicius Cordeiro, Rui Micaelo
Abstract
Despite asphalt self-healing with encapsulated rejuvenators having been intensively researched over the last decade, there is still uncertainty about the performance advantages granted by this technology. As a way of adding to the existing set of research methodologies, this study aimed to test the feasibility of a visual method to investigate the working mechanism of encapsulated rejuvenators in the bituminous mixture. For this purpose, clear bituminous mixtures were produced using a colorless synthetic binder and a pigment was added to the rejuvenator incorporated in the calcium alginate capsules. The internal structure of the bituminous mixtures containing these capsules was inspected both on loaded and unloaded specimens. The colored rejuvenator was also directly added to cracked specimens and its distribution was studied, along with the interaction between the rejuvenator and the synthetic binder. The results show that the rejuvenator could modify the binder to a limited extent, and the bituminous mixtures containing capsules showed evidence of rejuvenator release. It is demonstrated that the aggregate gradation of mixtures has a significant effect on capsule damage and rejuvenator release. However, the pigment can be filtrated from the rejuvenator by the capsule polymer structure and the asphalt. Even though the methodology presented some constraints, it has been proven to be capable of achieving the initial goal, while also acting as an important first step in the visual study of rejuvenator release in asphalt.