Towards more durable recycled bituminous composites

Recycling of oxidized bitumen requires proper dissociation and peptizing of bitumen nanoaggregates referred to as rejuvenation. While there are many modifiers or so-called rejuvenators to perform the latter dissociation and peptizing actions, some of them compromise durability of recycled bitumen by inadvertently increasing its susceptibility to moisture damage. Here, we study moisture resistance of laboratory aged bitumens for which a synthesized rejuvenator referred to as Switein was used. In this study, Switein is prepared from a blend of lipid and protein via co-processing of food waste and animal waste through thermochemical conversion. Study results showed that the rejuvenator effectively restored the crossover modulus properties of all aged bitumens regardless of their aging levels. Restoration effectiveness was also verified by Glover-Rowe (G-R) parameters and healing indexes. A durability comparison showed that the resistance to moisture damage in bitumens rejuvenated with Switein was much higher than those rejuvenated by another bio-based rejuvenator. It should be noted that both rejuvenators were effective to restore physio-chemical and rheological properties of aged bitumens. This in turn highlights the importance of factoring in durability effects of rejuvenators among their selection criteria. The study outcomes emphasize the significance of using a chemistry-informed design for bitumen modifiers to ensure not only proper restoration is achieved, but also durability is not compromised.