Investigation of the behavior of asphalt tack coat interface layer.

Details

• Creators:
  Mohammad, Louay N. ; Wu, Zhong ; Raqib, Md. Abdur
• Corporate Creators:
  Louisiana Transportation Research Center
• Subject/TRT Terms:
  Asphalt Asphalt Cement Binders Emulsion Emulsions Interface Bond Strength Interfaces Shear Strength Shear Tests Simple Shear Test Tack Coat Tack Coats Temperature

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• Publication/ Report Number:
  FHWA/LA.04/394
• Resource Type:
  Tech Report
• Geographical Coverage:
  Louisiana
• Corporate Publisher:
  Louisiana Transportation Research Center
• Abstract:
  Asphalt tack coat is a light application of asphalt, usually asphalt diluted with water. It ensures a bond between the surface being paved and the overlying course by providing increased shear strength between two interfaces. Normally hot asphalt cements, emulsified asphalts or cutback asphalts are used as tack coat. The objective of this study was to evaluate the practice of using tack coats through controlled laboratory simple shear tests and determine the optimum application rate. The influence of tack coat types, application rates, and test temperatures on the interface shear strength was examined. Six emulsions (CRS-2P, CRS-2L, SS-1, CSS-1, SS-1h and SS-1L) and two asphalt binders (PG 64-22 and PG 76-22M) were selected as tack coat materials. The residual application rates considered were 0.00 l/sq m (0.00 gal/sq yd), 0.09 l/sq m (0.02 gal/sq yd), 0.23 l/sq m (0.05 gal/sq yd), 0.45 l/sq m (0.1 gal/sq yd), and 0.9 l/sq m (0.2 gal/sq yd). A simple shear test was performed to determine the shear strength at the interface at two test temperatures, 25 deg C (77 deg F) and 55 deg C (131 deg F). The influence of vertical load levels on interface bonding strength was evaluated using the optimum tack coat material and application rate. Based on the statistical analysis of the interface bond strengths provided by various tack coat types at different application rates, both CRS-2P and CRS-2L were identified as the optimum tack coat types among the eight tack coats considered in this study. The preliminary test results indicated that CRS-2P emulsion provided the highest interface bond strength at the test temperature of 25 deg C (77 deg F) whereas CRS-2L provided the highest interface bond strength at the test temperature of 55 deg C (131 deg F), both at an optimum residual application of 0.09 l/sq m(0.02 gal/sq yd). In addition, it was found that shear resistance at the interface increased significantly with an increase in vertical load and decreased with an increase in temperature.
• Format:
  PDF
• Funding:
  State Project 736-99-1028 ; LTRC Project 00-2B
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:034858af6d6431705d2729a7a8ce47f37ab487220f7ec40cdcf139c59599f9a0
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/22149/dot_22149_DS1.pdf
• File Type:
  [PDF - 2.69 MB ]