Project Number: CY2-OU-LTU-12
Project Title: Improved Pavement Durability and Climate Resiliency Using Balanced Mix Design with High RAP and Rejuvenator: A Path Toward Statewide Implementation
Performing Institution: University of Oklahoma and Louisiana Tech University
Principal Investigator: : Syed Ashik Ali, Kenneth Hobson, and Musharraf Zaman, University of Oklahoma; Nazimuddin Wasiuddin, Louisiana Tech University
Proposed Start and End Date: 10/01/2024 to 09/30/2025
Project Description: This research initiative, developed in consultation with the Materials Division of the Oklahoma Department of Transportation (ODOT), addresses a critical agency need related to the statewide implementation of Balanced Mix Design (BMD). Two SPTC partner institutions, namely the University of Oklahoma (OU) and Louisiana Tech University (LTU), will collaborate to accomplish the goals of this research. Incorporating Reclaimed Asphalt Pavement (RAP) into asphalt mixes offers significant benefits, including reduced cost, resource conservation, energy savings, enhanced sustainability, and reduced environmental impact. With a focus on achieving reduced environmental impact, increasing RAP usage in asphalt mixes can substantially lower the environmental impacts of pavement materials. However, challenges such as variations in material property and a lack of performance data complicate the design of asphalt mixes with high RAP content. ODOT has been actively implementing BMD through pilot projects and research, allowing up to 15% RAP for surface courses and 20% for base courses. This project aims to further increase the RAP content using the BMD approach.

A key factor in the performance of RAP-containing asphalt mixes is the aging of the asphalt binder. Rejuvenators can replenish the volatiles and light binder fractions, restore the mechanical and chemical properties lost due to aging and aid in meeting the BMD design criteria. While rejuvenators generally reduce the stiffness of the asphalt mix, their effects on binder and mix properties need evaluation, along with determining the optimum amount of rejuvenator for satisfactory performance. This collaborative study focuses on designing high-RAP asphalt mixes using commercially available rejuvenators and the BMD approach, followed by performance evaluation of field test sections. LTU will investigate the properties of asphalt binder blends with high RAP and rejuvenators, while OU will focus on the mix design.
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