Towards advanced sustainable technologies for asphalt pavement materials

The transportation sector remains one of the largest contributors to the greenhouse gas emissions in the United States, per economic sector, accounting for 28 percent of the total emissions nationwide. In particular, the asphalt industry holds major responsibility in the transportation infrastructure sector as 94 percent of all paved roads in the U.S. are asphalt overlays or full-depth pavements. Therefore, advancing technologies that reduce the material-level carbon emissions while ensuring structural performance is a critical step toward national sustainability goals. This dissertation addresses the need to develop a comprehensive and inclusive asphalt mixture design framework that incorporates mixture resistance to pavement distresses and associated environmental impacts. This framework is subsequently integrated into a decision-support system for efficient and feasible optimization of pavement sustainability and engineering performance. The research is conducted around four core objectives: (1) identifying mixture parameters that critically influence the Global Warming Potential (GWP) of asphalt mixtures; (2) establishing a GWP benchmarking methodology and GWP thresholds for practical implementation, (3) evaluating performance implications and the environmental effects of incorporating recycled materials such as reclaimed asphalt pavement, engineered crumb rubber and post-consumer polymers into routine asphalt mixtures; and (4) developing an adapted, LCA-integrated Balanced Mix Design (BMD) framework that enables practitioners to meet both performance criteria and environmental thresholds simultaneously. Extensive analyses of asphalt Environmental Product Declarations (EPDs) were conducted to identify the key factors influencing GWP during the material production stages. Findings revealed that the material acquisition phase is the dominant contributor to total emissions, largely driven by asphalt binder production and content. Specialty mixtures and mixtures with polymer-modified binders were also found to have increased environmental impacts. Furthermore, the study highlighted the necessity for establishing standardized GWP thresholds to objectively define what constitutes an acceptable environmental performance for asphalt mixtures. To address the limitations of existing GWP benchmarking methodologies, a new application-based benchmarking approach was developed. The proposed benchmarks provide phase-specific and mix-type or application-specific GWP thresholds that reflect real-world contractor practices, local specifications, and mixture production trends. This creates a more implementable system, supporting potential use in procurement incentives, material qualification processes, and agency-wide sustainability programs. Laboratory performance testing was conducted to assess the feasibility of incorporating recycled materials into routine and high environmental-impact asphalt mixes i.e., stone mastic asphalt and polymer-modified mixes. The mixes were developed through the Balanced Mix Design (BMD) methodology where the performance tests were applied to characterize the mixes across key pavement distresses. Specifically, rutting susceptibility was characterized via the Hamburg Wheel Tracking Test, intermediate-temperature cracking resistance was assessed using the IDEAL-CT procedure, and low-temperature fracture performance was quantified through the Disk-Shaped Compact Tension (DC(T)) test. rutting (Hamburg Wheel Tracking Test), intermediate-temperature cracking (IDEALCT test), and low-temperature cracking (Disk-shaped Compact Tension test). Moreover, laboratory investigations assessed strategies to reduce GWP through mix design optimization and material selection. The incorporation of reclaimed asphalt pavement (RAP) was identified as the most effective mitigation measure, followed the use of asphalt binders with lower GWP impacts and finally, lowering binder content through the use of recycled polymers such as post-consumer polyethylene. The outcomes of this work culminated in the development of a comprehensive decisionsupport framework that integrates LCA and BMD principles, enabling simultaneous evaluation of mechanical and environmental metrics. This framework provides a scientifically defensible tool for policymakers, engineers, and contractors to design asphalt mixtures that optimize both performance and sustainability, thereby advancing state-of-the-art pavement engineering practices.