Developing Long-term Aging Protocols for Cracking Performance Evaluation of Asphalt Mixtures in Virginia

Project No: 122013

Target Completion Date: January 31, 2025 Pavements

About the project:

The Virginia Department of Transportation (VDOT) currently requires the use of the Indirect Tensile Cracking Test (IDT-CT) as specified in ASTM D8225-19 in its Balanced Mix Design (BMD) specification to assess the cracking susceptibility of dense-graded asphalt surface mixtures (SM) with “A” (PG64S-22) and “D”(PG64H-22) designations (i.e., 0 to 3 million equivalent single axle load [ESAL] range for A mixtures and 3 to 10 million ESAL range for D mixtures). A current performance criterion requiring a minimum cracking tolerance (CT) index of 70 was recommended to alleviate the cracking susceptibility of the asphalt mixtures based on extensive mixture testing. This CT index was determined based on testing of compacted specimens from reheated plant-produced asphalt mixtures. Although the current cracking testing protocol and its threshold value (i.e., CT index of 70) in VDOT’s BMD specification is indicative of the cracking performance of asphalt mixtures, it does not account for how the performance of asphalt mixtures throughout the service life is affected by oxidative aging (i.e., as it experiences long-term aging). Thus, laboratory evaluation of the long-term oxidative aging characteristics of asphalt mixtures is essential to ensure that the asphalt mixtures within the pavement structures continue to perform adequately throughout their service life. The objective of this research is twofold: (I) to develop practical long-term aging protocols for asphalt SMs with A and D designations that can be used in mix design verification and production of asphalt mixtures for quality control and acceptance purposes; and (II) to develop preliminary performance criteria for CT index for the to-be-developed long-term aging protocols. 

Project Team

Principal Investigators

Co-Principal Investigators

Project Monitor

Other Investigators

  • Ellie Hajj

Last updated: December 10, 2023

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