Retracted: Quantum-Chemistry–Based Study of Beech-Wood Lignin as an Antioxidant of Petroleum Asphalt

Abstract

Oxidative hardening or aging of asphalt binder can lead to increase in viscosity, separation of components, loss of cohesion and adhesion, and eventually the degraded engineering performances. A common practice to minimize asphalt aging has been to use chemical additives or modifiers as antioxidants. The current state of knowledge in asphalt oxidation and antioxidant evaluation concentrates on monitoring the degradation in asphalt’s physical properties, mainly the viscosity and ductility. Such practices although satisfying direct engineering needs does not contribute to the fundamental understanding of the asphalt aging and antiaging mechanisms. As such, this study was initiated to study the antioxidation mechanisms of bio-based additives, using the beech-wood lignin as an example, by developing a quantum-chemistry based chemophysical environment in which the various chemical reactions among asphalt components, antioxidative ingredients and oxygen molecules, as well as the incurred physical changes can be studied. The techniques of X-ray photoelectron spectroscopy (XPS) were used to prove the validity of the modified and unmodified asphalt models.