Develop Laboratory Mix Design of Full Depth Reclamation (FDR) Projects Using Foamed Asphalt Binder and Emulsified Asphalt

Full-depth reclamation (FDR) is a cost-effective recycling strategy that reuses both asphalt bound materials and unbound granular materials. FDR using cement or fly ash was implemented in Texas in the early 1990’s in the Bryan and Lubbock Districts. In the past 5 years, TxDOT has also implemented FDR using either foamed asphalt or emulsions. Test procedure and specifications for these asphalts based stabilizers have been proposed.The current procedure allows for samples to be compacted to either 4" diameter by 2.5" height or 6" diameter by 3.7" height; however, the indirect tensile (IDT) strength acceptance criteria are identical for both sample sizes, raising concerns regarding the effect of sample size and maximum aggregate size used to prepare the IDT samples. In a recent limited study, the effect of sample size on IDT strength of FDR mixtures was evaluated and it was observed that all 6" diameter samples had lower IDT strength as compared to the 4" diameter samples regardless of the material source, binder type, binder content, or conditioning procedure... This indicated that the IDT strength acceptance criteria included in TxDOT's current specifications for FDR mixtures need to be revised to reflect the differences in sample size. In addition, the current TxDOT IDT strength acceptance criteria for FDR mixtures is not based on field performance, rather on previous research from various organizations with different climates and locations. The research team will (1.) Review previous literature related to FDR mixtures, using both asphalt emulsions and foamed asphalt, that defines mix design methods including sampling, mixing water content, mixing methods, compaction, conditioning, test methods, test temperature and acceptance criteria. (2.) Conduct a comprehensive lab testing program to evaluate the differences in IDT strength between 4" and 6" diameter specimens considering different material source, binder type, binder content, and conditioning procedure. (3.) Define the effect of testing temperature on IDT strength considering different material source,binder type, binder content,and conditioning procedure. (4.) Propose revised IDT strength acceptance criteria for the 4" and 6" diameter specimens. (5.) Validate the proposed IDT strength acceptance criteria with selected field sections.

Language

  • English

Project

  • Status: Active
  • Funding: $885286
  • Contract Numbers:

    0-7076

  • Sponsor Organizations:

    Texas Department of Transportation

    125 E. 11th Street
    Austin, TX  United States  78701-2483
  • Managing Organizations:

    Texas Department of Transportation

    125 E. 11th Street
    Austin, TX  United States  78701-2483
  • Project Managers:

    Steele, Joanne

  • Performing Organizations:

    Texas A&M Transportation Institute

    Texas A&M University System
    3135 TAMU
    College Station, TX  United States  77843-3135
  • Principal Investigators:

    Scullion, Tom

  • Start Date: 20200901
  • Expected Completion Date: 20240831
  • Actual Completion Date: 0

Subject/Index Terms

Filing Info

  • Accession Number: 01766409
  • Record Type: Research project
  • Source Agency: Texas Department of Transportation
  • Contract Numbers: 0-7076
  • Files: RIP, STATEDOT
  • Created Date: Mar 2 2021 4:01PM