1401 N. Pine St., Rolla, MO 65409

Rebecca Herndon, a doctoral candidate in civil engineering, will defend their dissertation titled “NMR Relaxometry Approach for the Detection of Asphalt Binder Performance Properties.” Their advisor, Dr. Magdy Abdelrahman, is professor in the civil, architectural, and environmental engineering department. Their co-advisor, Dr. Klaus Woelk, is associate professor in the chemistry department. The dissertation abstract is provided below.

Asphalt is a necessary material for transportation infrastructure. Understanding the material properties of asphalt binders is critical for improving infrastructure and enhancing the lifetime of pavements. While the physical properties of asphalt binders are well-defined by standard procedures and parameters, the chemical environment lacks definition. Physical parameters like viscosity and stiffness are traditionally used to differentiate asphalt binders, describe aging, and indicate the impact of additives. However, these tests have limited insight into the material's chemical environment. Therefore, a nondestructive analytical technique, nuclear magnetic resonance (NMR) relaxometry, was employed to investigate the chemical environment of asphalt binders. Although NMR relaxometry has been widely used to describe the elastic behavior of polymers and has even been applied in situ on asphalt pavements, an in-depth study on asphalt binders remains unexplored. This research outlines new procedures to detect and quantify key performance properties of asphalt binders through NMR relaxometry, specifically by using 1H NMR T1 relaxation analysis. The work focuses on evaluating modified asphalt binder performance including the effects of standard aging and UV radiation-induced aging, binder content in hot-mixed asphalt, rejuvenation mechanisms, binder grades, and aging indicators. The research culminates in the development of a new asphalt binder performance parameter, termed “Herbaw.” Furthermore, a standardized sample preparation method, the “chocolate-covered pretzel” technique was introduced to ensure consistency in the sample preparation of asphalt binder samples for NMR analysis.

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