Evaluation of Balanced Asphalt Surface Mixtures with Conventional and High RAP Contents Using Laboratory and Accelerated Pavement Testing

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dc.contributor.authorTong, Bilinen
dc.contributor.committeechairFlintsch, Gerardo W.en
dc.contributor.committeememberBrand, Alexander S.en
dc.contributor.committeememberKaticha, Samer Wehbeen
dc.contributor.committeememberHabbouche, Jhonyen
dc.contributor.committeememberDiefenderfer, Brian Keithen
dc.contributor.departmentCivil and Environmental Engineeringen
dc.date.accessioned2025-01-23T09:00:40Zen
dc.date.available2025-01-23T09:00:40Zen
dc.date.issued2025-01-22en
dc.description.abstractBalanced Mix Design (BMD) represents an asphalt mixture design methodology that replaces certain traditional volumetric parameters with performance-based testing to address predominant distresses such as rutting and cracking. This approach offers an avenue to properly design and produce engineered asphalt mixtures, including those with high reclaimed asphalt pavement (HRAP) contents, recycling agents (RAs), fibers, and polymer-modified binders. Laboratory performance tests are essential to the BMD process, as they ensure the production of durable, high-performance materials. Beyond laboratory performance evaluation, accelerated pavement testing (APT) plays a crucial role in bridging the gap between laboratory material characterization and field pavement performance. This dissertation aimed to assess the BMD concept for designing durable, long-lasting surface mixtures in Virginia, with particular emphasis on higher RAP content mixtures (HRAP mixtures, i.e., exceeding 30% RAP). The study involved laboratory and APT testing of six surface mixtures featuring a range of RAP contents (both conventional and high), two binder grades (PG 64-22 and PG58-28), one RA, and one warm mix additive. Findings indicated that dense-graded, unmodified surface mixtures with higher RAP contents can be successfully designed using the current Virginia Department of Transportation (VDOT) BMD special provision. These mixtures can be produced in the plant with no significant deviations in aggregate gradation and asphalt binder content from the design specifications. The combined effect of variations in different volumetric properties during production may influence the primary performance of the mixtures, potentially resulting in an imbalance. As a consequence, the produced BMD mixture may fail to meet one or more performance thresholds. Additionally, the results underscored the effectiveness of BMD concept with incorporating RAs and/or a softer binder when designing HRAP surface mixtures. Importantly, the current selected BMD tests characterized the laboratory performance of mixtures, aligning with the performance observed under APT. This research provided a steppingstone towards the examination and validation of the VDOT BMD thresholds, which ensures satisfactory field performance. The study also indicated that while current BMD thresholds provided sufficient margins for satisfactory field cracking performance, rutting resistance may become a concern for overly designed BMD HRAP mixtures. For instance, mixtures with excessively high asphalt binder content may exhibit compromised rutting resistance. Furthermore, to address the challenges uncovered during BMD test analysis—issues like the constraints of traditional pair-wise comparisons, risks of repetitive design processes, and the difficulty in pinpointing critical factors in mixture production—this dissertation proposed innovative solutions to enhance BMD application and streamline the evaluation process. First, a novel Composite Performance Index (CPI), visualized through a 3D plot, captured the "balance" status of various mixtures. Second, a machine learning-enhanced BMD framework was introduced, offering intelligent optimization throughout the design and production phases. The integration of these two tools offers significant potential for simultaneously improving multiple performance indices of asphalt mixtures. Finally, this research demonstrated that the performance of higher RAP content mixtures can exceed that of lower RAP content mixtures through the application of BMD approaches. This dissertation not only advanced the implementation of BMD for surface mixtures but also contributed to the sustainable and performance-driven evolution of asphalt mix design. The insights gained from this study provided practical guidance and strategic recommendations for enhancing asphalt mixture design, production, and performance monitoring.en
dc.description.abstractgeneralThis dissertation evaluated a new way to design asphalt mixtures, called Balanced Mix Design (BMD). Unlike traditional methods that focus mostly on fundamental volumetric properties of materials, BMD uses testing to ensure the pavement will hold up against common issues like cracking and rutting. This approach allows for better use of materials, including high recycled asphalt pavement (HRAP), recycling agents (RAs), fibers, and modified binders. Considering economic and environmental benefits, the study evaluated the application of BMD for designing durable asphalt surfaces for pavements, particularly mixtures with over 30% recycled asphalt pavement (RAP). Tests in the laboratory and with accelerated pavement testing (APT) showed that high RAP mixtures could be designed and produced reliably using current Virginia Department of Transportation (VDOT) guidelines. The addition of recycling agents or softer binders further supported these mixtures in meeting performance standards, ensuring satisfied field performance. To address key challenges, such as the limitations of traditional pair-wise comparisons, risks of repetitive design processes, and the difficulty in finding key factors for production variability, this research introduces two innovative tools to enhance BMD. First, a Composite Performance Index (CPI) with a 3D visual tool offers a way to assess the balance status of mixtures. Second, a machine learning framework was developed to optimize BMD throughout the design and production phases. Together, these tools establish BMD as a valuable approach for designing and producing more sustainable, longer-lasting pavements.en
dc.description.degreeDoctor of Philosophyen
dc.format.mediumETDen
dc.identifier.othervt_gsexam:42302en
dc.identifier.urihttps://hdl.handle.net/10919/124318en
dc.language.isoenen
dc.publisherVirginia Techen
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subjectSustainable Pavementen
dc.subjectAccelerated Pavement Testingen
dc.subjectHigh Reclaimed Asphalt Pavementen
dc.subjectBalanced Mix Designen
dc.subjectPerformance Testingen
dc.titleEvaluation of Balanced Asphalt Surface Mixtures with Conventional and High RAP Contents Using Laboratory and Accelerated Pavement Testingen
dc.typeDissertationen
thesis.degree.disciplineCivil Engineeringen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.leveldoctoralen
thesis.degree.nameDoctor of Philosophyen

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