Practical Long-Term Oven-Aging Protocols for Balanced Mix Design: From Mixture Design to Production

The implementation of balanced mix design (BMD) frameworks by state highway agencies has increased the emphasis on performance-indicative tests for asphalt mixture design and production. However, although short-term oven aging (STOA) is routinely applied to simulate production and early-life conditions, long-term oven aging (LTOA) methods remain underutilized owing to their logistical complexity. To address this gap, the Virginia Department of Transportation (VDOT) evaluated streamlined LTOA protocols for dense-graded asphalt surface mixtures with unmodified binders. Laboratory-mixed and laboratory-compacted mixtures, as well as plant-mixed and laboratory-compacted specimens, were tested using the indirect tensile cracking test under various aging regimes. Binder rheological indices, Glover–Rowe parameter, phase angle at |G*| = 10 MPa, and ΔTc, were also evaluated to establish binder–mixture linkages. The results showed that 6 h of oven aging at compaction temperature (inclusive of 4-h STOA) corresponded to approximately 6 to 8 years of field aging. A preliminary cracking tolerance index threshold of 55 was recommended for LTOA evaluation, supported by binder index correlations and regression-based estimates of field cracking. The study also demonstrated the decisive role of binder quality, with underperforming mixtures substantially improving when refabricated with a higher-quality binder source. Finally, comparisons between design and production aging revealed that nonreheat production was roughly equivalent to 2 h of STOA, requiring an additional 4 h to match design LTOA, whereas reheated production required 2 h of additional conditioning after reheating. Collectively, the findings provide a practical and performance-based framework for incorporating LTOA into VDOT’s BMD practice.