Degree

Doctor of Philosophy (PhD)

Department

Civil & Environmental Engineering

Document Type

Dissertation

Abstract

Open-graded friction course (OGFC) is a thin asphalt mixture surface layer with a high percentage of coarse aggregates and high interconnected air voids, which provides improved skid resistance, visibility, and decreased pavement-tire noise. However, construction personnel at DOTD reported that conventional OGFC mixtures have short service life (raveling distress). Further, their structural contribution to the pavement structure is commonly neglected and designed only for functionality purposes.

The objective of this study was to develop a rational mix design methodology to improve the durability of OGFC asphalt mixtures. Specific objectives are to: (1) conduct a rheological and chemical characterization of polymer-, rubber-, and epoxy-modified asphalt binders; (2) evaluate the effect of various asphalt binders on laboratory performance of open- graded friction course mixtures (3) evaluate and compare the influence of different asphalt binder types on OGFC mixtures across different aging levels and moisture conditioning methods; (4) quantify the structural contribution of thin asphalt mixtures including coarse-graded and OGFC mixtures with polymer and epoxy modified asphalt binders.

Five types of asphalt binders were utilized: control PG 76-22m, PG 88-28 (high polymer), 25% and 50% diluted epoxy asphalt (EA) binder (PG 70-22), and a hybrid polymer and rubber PG 76-22CS asphalt binders. Chemical compatibility and microscopic analyses were first conducted on EA binders for selecting the most compatible base asphalt binder for dilution. Asphalt binder testing, including performance grading, multiple stress creep recovery, frequency sweep, linear amplitude sweep, SARA fractionation, and Fourier-transform infrared spectroscopy. OGFC mixture testing, including asphalt draindown, water permeability, Hamburg wheel track, modified Lottman, dynamic modulus, semi-circular bend, and Cantabro abrasion loss. Results showed that the developed mix design methodology yielded stable aggregate structure, interconnected air voids, and improved performance for OGFC mixtures. The chemical reaction between epoxy resin and asphalt binder formed a cross-linked network that resulted in improving OGFC performance for high-, intermediate-, and low-temperature. Pavement structural analysis results showed that incorporating OGFC mixtures in the pavement system improved permanent deformation and fatigue cracking resistance by 14.9% and 11.2%, respectively, for one inch thickness. Mixture with high polymer asphalt binder was the most cost-effective followed by EAB mixtures.

Date

4-3-2025

Committee Chair

Dr. Louay N. Mohammad

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Available for download on Friday, April 03, 2026

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