Evaluation of Aggregate Gradation Specifications and the Feasibility of Harmonization With AASHTO Standards

Details

• Creators:
  Elgaali, Husam H. ; Shah, Ayesha ; Olek, Jan
• Corporate Creators:
  Purdue University. Joint Transportation Research Program
• Corporate Contributors:
  Indiana Department of Transportation ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  • Aggregates by gradation
  • Mixtures
  • Optimization
  • Concrete pavements
  • Asphalt pavements
  • Specifications
  • Feasibility analysis
  • Surveys
  • AASHTO
  • ASTM
  More +
• Publication/ Report Number:
  FHWA/IN/JTRP-2026/19
• DOI:
  https://doi.org/10.5703/1288284318648
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Indiana
• Edition:
  Final Report: January 6, 2025-June 2, 2026
• Corporate Publisher:
  Purdue University. Joint Transportation Research Program
• Abstract:
  The aggregate gradations specified by the Indiana Department of Transportation (INDOT) differ from those of the American Association of State Highway and Transportation Officials (AASHTO). Preliminary discussions suggest that adopting AASHTO standard gradation sizes could provide national alignment and simplify production for those operating in multiple states and supplying projects not subject to INDOT specifications. A comprehensive study was performed to evaluate the current INDOT specifications for coarse and fine aggregate gradations and to assess the potential impacts and feasibility of adopting AASHTO-specified gradations. A comparative analysis of INDOT gradations against AASHTO, ASTM International (ASTM), and those of neighboring states (Ohio, Illinois, Kentucky, and Michigan) was performed. Specifically, the study examined gradations used in concrete, asphalt, and unbound applications. Additionally, surveys and interviews were conducted with industry stakeholders (e.g., producers, contractors, and engineers) in the aggregate, concrete, and asphalt sectors to gain further insight. Results showed that AASHTO offers gradations similar to those currently used by INDOT. Industry stakeholders indicated that transitioning to AASHTO could provide uniform standards with neighboring states and other entities (e.g., ASTM, Federal Aviation Administration), generate economic benefits, improve production consistency, and enhance operational efficiency. Concrete and asphalt stakeholders suggested that adopting these gradations could provide greater flexibility for designing and optimizing mixtures. To shift to aggregate gradations specified by AASHTO, it is advisable to create a comprehensive, multistep plan to reduce disruptions to ongoing projects and the operational processes of industry stakeholders.
• Format:
  PDF
• Funding:
  SPR-4914
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/93463/dot_93463_DS1.pdf
• File Type:
  [PDF - 8.06 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:8e158b014ec6600bf81382dcb57559364294aebab9217c79adb9597c0b87f378296bcc89f7c4330810ab59f76a976ae24b7ed4952763c54be0e95a27d3a56559