Development of Balanced Mix Design Procedure

Asphalt mixture design involves the determination of the best combination of available materials for optimum in-service performance. Past and current mixture design methodologies, including the prevalent Superpave approach, principally rely on volumetric parameters (e.g., air voids and VMA) to ensure good performance without direct performance measures and criteria incorporated into them. A number of state departments of transportation have recognized the shortcomings of a volumetric only approach. Several states have adopted some form of a Balanced Mix Design (BMD) approach. For BMD, acceptable rutting and cracking resistance is exhibited over a range of binder contents such that the mixture performance is considered “balanced”. For this research, 36 Tennessee Department of Transportation (TDOT) asphalt mixtures were identified from across the three geographical regions of the state: east, middle, and west. These mixes also represented various aggregate and binder types and included RAP. The BMD evaluation involved mixtures prepared in the laboratory at the optimum binder content and 0.5% above the optimum binder content. Prospective BMD tests included the Hamburg Wheel Tracking Test, the Rutting Resistance Tolerance Test (RTIndex) and the Indirect Tensile Asphalt Cracking Test (CTIndex). In addition, three (3) Job-Mix Formulas (JMFs) were identified as representative for the respective east, middle and west regions of the state. Twelve (12) projects were then chosen for which there was significant confidence that the projects were paved with one of the selected JMFs. More specifically, three (3) projects were chosen that were associated with the east and west regions of the state while six (6) projects were chosen for the Middle Tennessee JMF. These 12 projects were cored, and the upper surface layer(s) were tested to assess cracking performance with respect to the laboratory cracking resistance testing (CTIndex). Test results showed the expected sensitivity to increased binder content indicating promise for BMD application in Tennessee.

Language

  • English

Project

  • Status: Completed
  • Funding: $194854
  • Contract Numbers:

    RES2019-05

  • Sponsor Organizations:

    Tennessee Department of Transportation

    James K. Polk Building
    Fifth and Deaderick Street
    Nashville, TN  United States  37243-0349
  • Managing Organizations:

    Tennessee Department of Transportation

    James K. Polk Building
    Fifth and Deaderick Street
    Nashville, TN  United States  37243-0349

    Lipscomb University

    One University Park Drive
    Nashville, TN  United States  37204
  • Project Managers:

    Chandler, Matthew

  • Performing Organizations:

    Lipscomb University

    One University Park Drive
    Nashville, TN  United States  37204
  • Principal Investigators:

    Lynn, Todd

  • Start Date: 20181231
  • Expected Completion Date: 20210731
  • Actual Completion Date: 20220201
  • USDOT Program: Accelerating Project Delivery
  • USDOT Program: Innovative Safety, Resiliency, and All-Hazards Emergency Response and Recovery Research Demonstrations (SRER)

Subject/Index Terms

Filing Info

  • Accession Number: 01906746
  • Record Type: Research project
  • Source Agency: Tennessee Department of Transportation
  • Contract Numbers: RES2019-05
  • Files: RIP, STATEDOT
  • Created Date: Feb 1 2024 3:25PM