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Evaluation of Tack Coat Bond Strength Tests

File Language:
English


Details

  • Creators:
    Shuler, Scott
  • Corporate Creators:
  • Corporate Contributors:
    United States. Federal Highway Administration
  • Subject/TRT Terms:
  • Publication/ Report Number:
    CDOT-2018-14
  • Resource Type:
    Tech Report
  • Geographical Coverage:
    Colorado
  • Corporate Publisher:
    Colorado. Dept. of Transportation. Applied Research and Innovation Branch
  • NTL Classification:
    NTL-HIGHWAY/ROAD TRANSPORTATION-Materials
  • Abstract:
    Poor bonding between asphalt pavement overlays and the substrate pavement layer can greatly influence the long term performance of hot mix asphalt (HMA) in the form of premature cracking and fatigue. The primary method to achieve bonding between layers is by using an asphalt emulsion tack coat. Additionally, field staff is charged with determining whether an existing pavement, especially a milled surface, is clean enough prior to tack coat placement, to ensure an adequate bond. Because CDOT is prescriptive in its tack coat application specifications, responsibility for any pavement failures related to poor bonding lies with CDOT. However, if a performance related test to measure tack coat bond strength could be specified, failures related to poor bonding should be reduced. This study evaluated four bond strength tests for SMA and HMA overlays on HMA and Portland cement concrete pavements. Results of this study indicate that bond strength of HMA overlays can be measured using pavement cores, that a significant difference in test precision was observed when CRS-2P was used a tack coat and that one of the test pavements demonstrated significantly poorer than recommended bond strength for the tack coat utilized. Recommendations are provided for developing a performance related specification based on future performance observed on the four pavements. Implementation of this research can be done as follows: 1) specify a minimum tack coat application rate of 0.05 gal/sq-yd of 50:50 diluted CSS-1h or CRS-2P for construction of dense graded HMA over other dense graded HMA.
  • Content Notes:
    Sponsoring Agency Code Study #12.94 Performing Organization Report No. CDOT-DTD-R-2018-14
  • Format:
    PDF
  • Collection(s):
  • Main Document Checksum:
    urn:sha256:2bc656db4f98c29348388418a9976a51ef7cb0250dd8a7327c1193239c9bcc3b
  • Download URL:
  • File Type:
    Filetype[PDF - 668.77 KB ]
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