A modified thin-film protocol for accelerated simulation of long-term field aging in asphalt binders

Conventional 20-hour pressure aging vessel (PAV20) protocol is insufficient to simulate long-term aging of asphalt binders. A recent national project (NCHRP 09-61) suggested either reducing film thickness to 0.8 mm (Thin-Film PAV20) or extending the duration to 40 h (PAV40), both approximating 10 years of field oxidation. This study aims to validate and extend those findings by introducing a modified Thin-Film PAV20 protocol designed to improve binder film uniformity during sample preparation. Results showed that the modified Thin-Film PAV20 protocolproduceduniform binder films for both unmodified and polymer-modified binders, while yielding oxidation levels that consistently exceeded conventional PAV20 and remained comparable to or slightly higher than PAV40. Performance ranking revealed significant reordering of cracking resistance from PAV20 to PAV40 or Thin-Film PAV20, indicating that long-term oxidation reshapes the relative cracking resistance of asphalt binders. This finding underscores the importance of employing more severe aging simulations to assess binder durability.