Benefit/Cost of Applying a Higher Asphalt Film Thickness (AFT) versus Doing a Chip Seal at 1 Year

Project Details







Minnesota Department of Transportation

Principal Investigator
Ashley Buss

Faculty Affiliate

About the research

The overarching purpose of this study is to provide recommendations for keeping the pavement structure as moisture resistant as possible for the least amount of cost. Required minimum asphalt film thickness (AFT) is an important parameter when assessing the long-term durability of an asphalt mixture. Research shows higher film thicknesses create more durable mixtures. Minnesota specifications require a minimum AFT for mixture design acceptance. If the adjusted film thickness is below acceptable limits during production, large payment reductions or orders to remove and replace may result. Pavement preservation treatments are gaining momentum as cost-effective ways of enhancing pavement life. To prevent deterioration of pavements, chip seals are a proven preservation method and have been widely used in Minnesota. A Minnesota study estimated that a chip seal placed at the time of construction will be cost-effective if pavement life is extended by approximately 0.45 years. Typical life extension for chip sealed roads range 5 to 7 years. The value of AFT specifications has been debated within the paving community. This research offers an opportunity to validate current specifications, investigate the role of chip seals in pavement durability, and use lab and field data to perform a cost-benefit analysis of increased AFT and chip seals placed at 1 year. The objective of the research project is to perform a data-driven cost-benefit analysis of applying higher AFT and/or placing chip seals at 1 year of service. Data for the analysis will be collected from both laboratory performance testing and field performance. Pavement projects especially of interest are projects that incurred pay deductions due to low AFT and if/when chip seals were placed to preserve those roadways.