Date of Award

2026

Document Type

Campus Access Dissertation

Degree Name

Doctor of Philosophy in Civil Engineering (PhD)

Administrative Home Department

Department of Civil, Environmental, and Geospatial Engineering

Advisor 1

Zhanping You

Committee Member 1

Patricia A. Heiden

Committee Member 2

Muhammed Emin Kutay

Committee Member 3

Gregory Odegard

Committee Member 4

Yuhong Wang

Committee Member 5

Bo Xiao

Abstract

High-content crumb rubber–modified asphalt (CRMA) offers a sustainable approach to improving pavement durability while recycling waste tires, but its field constructability, performance variability, aging behavior, and recyclability remain insufficiently understood. This dissertation integrates field implementation with controlled laboratory investigations to evaluate wet- and dry-process CRMA from production through aging and rejuvenation. A full-scale wet-process pavement containing 22% CRMA was constructed on Dixie Highway in Michigan. Transitioning from a dense-graded to a gap-graded mixture eliminated roller pickup and improved constructability. The CRMA mixtures provided substantially greater cracking resistance, satisfactory moisture resistance, slightly lower noise levels, and favorable two-year field performance. Laboratory studies examined thermal storage, mixture curing, tire source, particle size, rubber content, shear intensity, aging, and rejuvenation. Binder storage for up to 24 h produced only modest overall changes in CRMA rheology, while approximately 2 h of loose-mixture curing substantially improved rutting resistance without eliminating the cracking advantage. Coarser rubber generally enhanced binder stiffness and high-temperature performance, whereas finer rubber improved storage stability and workability, and reduced asphalt consumption. Truck-tire rubber generally produced better mixture-level cracking and rutting performance than passenger-car-tire rubber at the same particle size. The effect of CR particle size on mixture cracking resistance depended on shear intensity, demonstrating that the rubber source, particle size, and production conditions interacted rather than acted independently. Binder-level trends did not always predict mixture behavior, emphasizing the importance of jointly considering rheology, rubber dispersion, compaction, aggregate structure, and production conditions. Increasing rubber content and shear intensity improved selected performance attributes, but excessive rubber content reduced workability. High-content CRMA exhibited better aging resistance, greater elasticity, and better cracking and low-temperature performance than conventional asphalt. Rejuvenation improved aged properties, and CRMA exhibited a stronger recovery response than conventional asphalt, indicating that it was more readily rejuvenated under the evaluated treatment, although excessive softening reduced rutting resistance. Overall, high-content CRMA can provide durable, crack-resistant pavements when gradation, curing, production conditions, and rejuvenation treatments are carefully optimized. These findings provide practical guidance for material selection, construction, durability management, and future recycling of CRMA pavements.

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