Date of Award

Fall 2026

Abstract

The transportation sector is confronted with the necessity of sustainability, and the utilization of recycling techniques in the construction and rehabilitation of asphalt pavements has emerged as a viable strategy for preserving pavement infrastructure. Among the various recycling methods, cold recycling is distinguished by its efficient reutilization of existing pavement materials, ease of mix preparation & construction, and reduced dependence on virgin materials and fossil fuels, thereby contributing to lower emissions. The three primary cold recycling techniques, cold in-place recycling (CIR), cold central plant recycling (CCPR), and full-depth reclamation (FDR), differ in their construction methodologies, material processing approaches, and the extent of recycling depth. However, they share a common material composition, primarily consisting of reclaimed asphalt pavement (RAP), stabilizing agents such as asphalt emulsion or foamed asphalt, and, in some cases, chemical additives and virgin aggregates. Recent advancements in emulsion chemistry, particularly the development and adoption of engineered emulsions, have further increased the adoption of cold recycling in the United States. Literature on this emulsion treatment is however limited, with unresolved questions regarding its long-term performance characteristics. More so, there is a lack of requisite data on the material properties needed for implementation in both the AASHTO 1993 empirical design and the mechanistic-empirical (M-E) design methods commonly used by various transportation agencies. These gaps restrict the extent to which the economic and environmental advantages of cold recycling can be realized. Hence, a comprehensive evaluation of these materials and the development of appropriate design tools are essential to prevent both over-design & under-design while ensuring adequate structural capacity and sustained serviceability.The primary goal of this dissertation is to enhance the structural design methodologies for engineered emulsion-stabilized cold recycled (CR-EE) pavements by appropriately characterizing and evaluating their properties and performance. This dissertation integrates field and laboratory data from in-place cold recycling techniques, specifically CIR and FDR, to develop mechanical property prediction models, structural layer coefficients for use within the AASHTO empirical design, and a rutting performance transfer function framework as part of M-E design, facilitating efficient design of CR-EE pavements. The developed mechanical property prediction models are embedded within a Microsoft Excel-based tool and rely on readily available mix design and/or quality assurance/quality control information such as stabilizer content (engineered emulsion), the presence of a chemical additive, RAP gradation characteristics, and density. These models are intended to estimate inputs for pavement analysis & design and to support material quality checks as part of quality assurance /quality control practices. In addition, as part of the M-E design framework established, a mechanistic parameter known as Deviator Stress Ratio (DevSR) is employed to establish a threshold to limit early life rutting of the CR-EE pavement layer.

Document Type

Dissertation

First Advisor

Eshan V Dave

Second Advisor

Mohamed Elshaer

Third Advisor

Ashley Buss

Department or Program

Civil and Environmental Engineering

Degree Name

Doctor of Philosophy

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