Date of Award

December 2022

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Civil Engineering

First Advisor

Daba Gedafa

Abstract

There is a broad consensus that the current mechanistic-empirical pavement design guideline (MEPDG) is an improvement from the earlier empirical-based design approaches. The lack of comprehensive material input databases for bound and unbound layers remains challenging. This study developed a database for binders used in typical hot mix asphalt (HMA) mixes in North Dakota by measuring their complex shear modulus (|G*|) and associated phase angle (δ) at unaged, short-term aged, and long-term aged conditions. Binder viscosity was also measured in these three aged states. Additionally, this study used existing models to predict (|G*|) and δ and compared them to measured values. Results illustrated that the aging effect increased binder viscosity; however, the values remained within the viscoelastic range. The |G*| and δ values for the unaged and short-term aged binders revealed that all the binders performed satisfactorily at high temperatures according to their performance grades. For unaged binders, the PG58H-34 for Highway (HWY) 83 and HWY 32 displayed different |G*| and δ values indicating the importance of undertaking local binder characterization. For short-term aged binders, PG 58H-34-HWY 83 showed high stiffness and high elasticity at high temperatures indicating that it is suited for pavements carrying heavy traffic. |G*| values increased significantly with long-term aging, with HWY 32 PG 58S-28 displaying the highest stiffness indicating a higher susceptibility to fatigue cracking in the future. Comparing the predicted and measured short-term aged |G*| and δ for the eight binders revealed mixed results. R2 values above 0.9 for predicted and measured |G*| for all the binders were observed, while for six binders, the R2 values were above 0.8 for predicted and measured δ, and for two binders, the R2 values were below 0.5. Using measured A and VTS values instead of default values is recommended as a remedy for poor phase angle predictions. Using the |G*|/sinδ parameter showed that PG 58H-34-HWY 94 had the highest rutting resistance, while the Multiple Stress Creep Recovery (MSCR) test showed that PG 58S-34-HWY 1was the most rut-resistant binder. |G*|. sin(δ) parameter indicated that PG58H-34-HWY 52 had the highest fatigue resistance, while the Linear Amplitude Sweep (LAS) test indicated that PG 58H-34-HWY 94 had the highest fatigue resistance. The binder ranking results did not match, meaning that further testing is required with the inclusion of independent tests to verify the rankings.

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