Performance Evaluation of Chip Seals in Idaho

The intent of this research project is to identify a wide variety of parameters that influence the performance of pavements treated via chip seals within the State of Idaho. Chip sealing is currently one of the most popular methods of maintenance for paved road surfaces. It entails spraying the pavement surface with asphalt (or “binder”) and then immediately covering it with aggregate (or “chips”) and using rollers to compress and settle the application. Chip sealing is used to seal non-structural cracks, increase surface friction, and improve ride quality. There are a variety of techniques and formulas (“design methods”) for mixing the binder and aggregate used in chip sealing. In Idaho, these design methods lack uniformity: empirical methods are used, based on an informal rule-of-thumb, the experiences of the parties making the chip seal, and the materials that are readily available. This project compares the methods used in Idaho with several different design methods that have been developed in various parts of the world. The project’s research focus is a series of laboratory experiments using different binders and aggregates obtained from all six Idaho Transportation Department districts. The results of these experiments have been compiled and analyzed, with the findings included herein. Chief among these findings, it was observed that the ratio of median size to flakiness index of the aggregate exhibits a better correlation with the percentage aggregate retained rather than the least dimension (as used in the commonly used McLeod Design Method). It was also found that the cleanness value of the aggregate is a critical factor for retaining aggregate -- i.e., keeping the chips on the treated road surface, rather than breaking free from the binder. This report concludes with a series of seven recommendations for improving chip sealing practice in Idaho, and with a list of eight areas worthy of additional research.

• Record URL:
  https://apps.itd.idaho.gov/apps/research/Completed/RP190.pdf
• 
• Record URL:
  https://rosap.ntl.bts.gov/view/dot/24632
• Corporate Authors:

  Idaho State University, Pocatello

  Department of Civil and Environmental Engineering
  Pocatello, ID  United States  83209-8060

  Idaho Transportation Department

  P.O. Box 7129, 3311 West State Street
  Boise, ID  United States  83707-1129

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Zoghi, M
  • Ebrahimpour, A
  • Pothukutchi, V
• Publication Date: 2010-8

Language

• English

Media Info

• Media Type: Print
• Edition: Final Report
• Features: Appendices; Figures; References; Tables;
• Pagination: 155p

Subject/Index Terms

• TRT Terms: Chip seals; Mix design; Pavement maintenance; Pavement performance; Performance measurement; Preservation
• Geographic Terms: Idaho
• Subject Areas: Highways; Maintenance and Preservation; Pavements; I61: Equipment and Maintenance Methods;

Filing Info

• Accession Number: 01370194
• Record Type: Publication
• Report/Paper Numbers: FHWA-ID-10-190
• Contract Numbers: RP 190
• Files: NTL, TRIS, USDOT, STATEDOT
• Created Date: May 16 2012 3:06PM