The National Academies

NCHRP 14-08 [Completed]

Chip Seal Coats for High-Traffic-Volume Asphalt Concrete Pavements

  Project Data
Funds: $80,078
Research Agency: Intermountain Research Foundation (University of New Mexico)
Principal Investigator: Dr. T. S. Shuler
Effective Date: 7/6/1987
Completion Date: 10/5/1990

Chip seal coats, usually applied to low-volume roads, are used to extend pavement service life by reducing water infiltration and improving skid resistance. The use of chip seal coats on high-traffic-volume roads has had limited application because of unknown cost effectiveness, potential windshield damage, unsatisfactory results because of lack of adherence to sound engineering principles, and traffic disruption during construction. However, chip seal coats may be suitable on roads with relatively high volumes, in the vicinity of 20,000 vehicles per day on four-lane roads, thereby postponing the need for overlays.

The objective of this research was to develop a workable system for applying chip seal coats to high-traffic-volume asphalt concrete pavements as a cost-effective alternative to asphalt concrete overlays. For purposes of this project high traffic volumes were defined as those in excess of 7,500 vehicles per day in one direction on a four-lane highway.

The literature review was completed, and an annotated bibliography was submitted. A poll of experienced personnel was conducted to (1) determine the extent of use of chip seals on high volume pavements, (2) determine materials, design methods, procedures, performance, etc., where chip seals are used, and (3) understand and quantify the effects of various factors on chip seal performance. The Interim Report for the project was submitted and approved by the project panel. One field test project in Tulsa, OK, on U.S. 169, was successfully accomplished. Four different treatments were investigated, along with two speeds of the pilot car.

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