Alireza Roshan, a doctoral candidate in civil engineering, will defend their dissertation titled “Advanced Asphalt-Based Binder for High Friction Surface Treatments (HFSTs): Balancing Performance, Compatibility, and Cost-Effectiveness.” Their advisor, Dr. Magdy Abdelrahman, is an professor in the civil, architectural and environmental engineering department. The dissertation abstract is provided below.

High Friction Surface Treatments (HFSTs) have proven highly effective in enhancing roadway safety, particularly at locations more prone to crashes, reducing wet-weather crashes by up to 80% and total crashes by 57%. However, traditional epoxy-based HFSTs face major challenges, including thermal incompatibility with asphalt pavements (with expansion and contraction rates 3–4 times higher), strict substrate requirements, and high installation and removal costs. The primary objective of this study was to develop and evaluate asphalt-based alternatives to epoxy binders for HFST applications that address these critical limitations while maintaining or improving safety performance. This research systematically progressed from evaluating conventional asphalt binders through increasingly advanced formulations, including highly-modified binders, specialized polymer-modified systems, emulsions, and mastics. The experimental program included comprehensive material characterization, performance evaluation, friction modeling, and economic assessment. Alternative aggregates were evaluated across different gradations to optimize compatibility with asphalt-based binders. The research demonstrates that highly modified asphalt-based HFSTs with optimized aggregate gradation can match or exceed epoxy-based systems, offering better thermal compatibility, lower costs, and broader applicability. It provides transportation agencies with cost-effective, compatible solutions to advance the implementation of these life-saving safety treatments.