Balancing Practicality and Field Relevance: A Laboratory Aging Protocol for Asphalt Surface Mixtures in Virginia
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Authors
Alam, Iftekar
Issue Date
2025
Type
Thesis
Language
en_US
Keywords
Aging , Asphalt , Balanced Mix Design , Cracking , IDEAL-CT , Pavement
Alternative Title
Abstract
Asphalt mixtures are critical to the construction and longevity of flexible pavements due to their favorable mechanical properties, ease of maintenance, and recyclability. However, they are inherently prone to cracking over time as a result of oxidative aging, traffic loading, and environmental exposure. To ensure long-term durability, it is essential to simulate and evaluate the aging behavior of asphalt mixtures through appropriate laboratory protocols. Long-term oven aging (LTOA) methods are designed to replicate field aging conditions and assess cracking resistance, but existing procedures often lack practicality or fail to capture performance variability across mixtures.This study presents a five-phase experimental framework to establish a practical and performance-based LTOA protocol for dense-graded surface mixtures used in Virginia. Phase 1 involved a mini-study on three laboratory-produced mixtures to determine a reduced LTOA duration at 95°C that reflects long-term field aging. Phase 2 expanded the analysis to ten mixtures aged at both reduced 95°C and compaction temperatures to determine equivalent aging durations and identify a practical LTOA method. Phase 3 utilized the Glover-Rowe parameter (GRP) to define CT Index thresholds for different levels of cracking severity. Phase 4 compared long-term performance under design and production conditions, identifying reheating-induced aging trends. Finally, Phase 5 incorporated FlexPave simulation and substitute-binder evaluations to assess the influence of binder quality on fatigue cracking over a 10-year period. The study recommends a practical LTOA protocol of 6 hours at compaction temperature for design, supported by strong correlations between the CT Index and binder rheological and chemical properties. A preliminary CT Index threshold of 55 is proposed for both design and production evaluations. Additionally, the study identifies 2 hours of aging after reheating and 4 hours of aging for non-reheat conditions as suitable LTOA durations during production. These findings offer a comprehensive and implementable approach for improving cracking performance evaluation within Balanced Mix Design (BMD) specifications in Virginia.