Interface Shear Strength Characteristics of Emulsified Tack Coats

This study evaluated interface shear strength of emulsified tack coats under a wide range of testing conditions that are commonly encountered in field applications. Three types of emulsified tack coats, CRS-1, SS-1h, and Trackless, were considered at three application rates, 0.14, 0.28, and 0.70 l/m2. In addition, a “no tack coat” condition was included in the analysis. The effects of construction conditions such as wet (rainfall) and dusty conditions were also evaluated. Laboratory direct shear tests were performed at 25C under two confinement pressures, 0- and 138-kPa. In order to simulate these test conditions, cores were extracted from a full-scale test site that was designed and constructed using conventional tack coat application and paving equipment. Results of this analysis showed that the trackless tack coat produced the highest shear strength at the three application rates, and SS-1 and CRS-1 resulted in the medium and the lowest strength, respectively. Within the considered application rate range, it was difficult to determine the optimum residual application rate. This may be attributed to the highly-oxidized and coarse HMA surface at the selected field site that required greater tack coat rates than expected. While higher application rates may increase interface shear strength, excessive tack coat may migrate into the HMA mat during compaction causing a decrease in the air void content in the mix. The majority of the cases showed statistically significant difference between clean and dusty conditions. However, no significant difference was found between dry and wet conditions. The results presented herein were part of the National Cooperative Highway Research Program (NCHRP) Project 9-40 on the “Optimization of Tack Coat for HMA Placement.”

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/02702932
• Authors:
  • Mohammad, Louay N
  • Bae, Abraham
  • Elseifi, Mostafa A
  • Button, Joe W
  • Scherocman, James A
• Conference:
  • Asphalt Paving Technology 2009
  • Location: Minneapolis MN, United States
  • Date: 2009-3-15 to 2009-3-18
• Publication Date: 2009

Language

• English

Media Info

• Media Type: Print
• Features: CD-ROM; Figures; Photos; References; Tables;
• Pagination: pp 249-278
• Serial:
  • Journal of the Association of Asphalt Paving Technologists
  • Volume: 78
  • Publisher: Association of Asphalt Paving Technologists (AAPT)
  • ISSN: 0270-2932
  • Serial URL: https://www.asphalttechnology.org/site_page.cfm?pk_association_webpage_menu=9169&pk_association_webpage=19109

Subject/Index Terms

• TRT Terms: Air voids; Coarse aggregates; Compaction; Dust; Emulsions; Hot mix asphalt; Rainfall; Shear strength; Tack coats; Texture
• Subject Areas: Highways; Materials; I33: Other Materials used in Pavement Layers;

Filing Info

• Accession Number: 01158673
• Record Type: Publication
• Files: TRIS
• Created Date: Jun 11 2010 12:05PM