A Field Torque Test System for Tack Coat Performance Evaluation

Tack coats are bituminous materials applied between pavement lifts to provide adequate bonding between the two surfaces. The absence, inadequacy or failure of this bond result in a significant reduction in the shear strength resistance of the pavement structure, making the system more vulnerable to distress types such as rutting, cracking and potholes. For this reason, monitoring the performance of the interlayer shear strength (ISS) during the pavement use phase and identifying bond failures are critical to improving pavement management systems and develop more efficient pavement design strategies. However, testing cores taken from roadways in the laboratory is not economical and practical. In addition, removal of full depth cores can affect the structural integrity of the pavement and can create localized failures. In this study, a low cost, practical, and less destructive prototype field test device, the Oregon Field Torque Tester (OFTT), is developed to evaluate the long-term post-construction tack coat performance of pavement sections. Correlations between OFTT field test results and the results of laboratory shear tests conducted with cores taken from the field were investigated to determine the effectiveness of the OFTT. The peak torque values measured by the OFTT were observed to be highly correlated with the measured laboratory shear strengths. The OFTT shear strength values calculated by using the torque test results and a theoretical equation were determined to be close to the measured laboratory shear strengths.

  • Supplemental Notes:
    • This paper was sponsored by TRB committee AFK40 Standing Committee on Surface Requirements of Asphalt Mixtures.
  • Corporate Authors:

    Transportation Research Board

  • Authors:
    • Mahmoud, Aiman
    • Coleri, Erdem
    • Batti, James
    • Covey, David
  • Conference:
  • Date: 2019


  • English

Media Info

  • Media Type: Digital/other
  • Features: Photos;
  • Pagination: 7p

Subject/Index Terms

Filing Info

  • Accession Number: 01697375
  • Record Type: Publication
  • Report/Paper Numbers: 19-05381
  • Files: TRIS, TRB, ATRI
  • Created Date: Mar 1 2019 3:50PM