Strategies for Improving the Cracking Resistance of Alabama Mixes

Details

• Creators:
  Sadeghi, Mohammad ; Hartzog, Zane ; Tran, Nam ; Yin, Fan ; Chen, Chen
• Corporate Creators:
  Auburn University. National Center for Asphalt Technology
• Corporate Contributors:
  Alabama. Department of Transportation. Bureau of Research and Development
• Subject/TRT Terms:
  Additives Aggregate Mixtures Asphalt Mixtures Cracking H-IDT HWTT IDEAL-CT Laboratory Tests Performance Resistance Tests Rutting

  More +
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Alabama
• Edition:
  Final Report: April 2023 – January 2026
• Corporate Publisher:
  Alabama. Department of Transportation
• Abstract:
  This project evaluated practical strategies for improving the cracking resistance of asphalt surface mixtures in Alabama while ensuring adequate resistance to rutting. The study focused on Superpave surface mixtures commonly used by the Alabama Department of Transportation (ALDOT) and examined three types of adjustments: binder content and grade, aggregate gradation and nominal maximum aggregate size, and chemical additives. Laboratory testing included the IDEAL-CT (i.e., AL-CT, outlined in ALDOT-459) for cracking resistance, as well as high-temperature indirect tensile strength (ALDOT-458) and Hamburg wheel-tracking tests for rutting resistance. The results indicated that decreasing the design air voids to increase the binder content led to incremental improvements in cracking resistance. While using a softer binder enhanced cracking performance, it reduced resistance to rutting. Alternatively, employing a polymer-modified binder improved both cracking and rutting performance, achieving a balanced outcome. Adjustments in aggregate gradation revealed that coarser gradations significantly enhanced cracking resistance while maintaining acceptable rutting performance. Strong correlations were observed between cracking performance and intermediate sieve sizes. Additionally, chemical additives improved cracking resistance in surface mixtures; however, their effectiveness varied based on the specific mixture. These strategies can be applied individually or combined to further enhance cracking performance while maintaining a balance in rutting resistance.
• Format:
  PDF
• Funding:
  931-104
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:aba81f626f0b7c5404765fd7592af7891ec79f84dd1f90212cedd8cf56eccdc53af5fde6d9c1872f75c3531ab1e18722339179803b2587038f29a46d0083e6ff
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/90535/dot_90535_DS1.pdf
• File Type:
  [PDF - 17.55 MB ]