New Project: Benefit/Cost of Applying a Higher Asphalt Film Thickness vs. Doing a Chip Seal at One Year

In Minnesota, reducing the effects of oxidation is a continuous challenge.

In a new study, funded by the Local Road Research Board, researchers will compare the effectiveness of two different methods: applying a surface treatment (typically a fog or chip seal) and increasing the asphalt film thickness during original construction.

The 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 ATF 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 (Wilde et al. 2014). Typical life extension for chip sealed roads range 5-7 years. The value of AFT specifications has been debated within the paving community.

This project 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.

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.

Project Details

  • Estimated Start Date: 07/20/2020
  • Estimated Completion Date: 07/31/2022
  • Funding: Local Road Research Board
  • Principal Investigator: Ashley Buss
  • Technical Liaison: Bruce Hasbargen

Details of the research study work plan and timeline are subject to change.

To receive email updates about this project, visit MnDOT’s Office of Research & Innovation to subscribe.

2 thoughts on “New Project: Benefit/Cost of Applying a Higher Asphalt Film Thickness vs. Doing a Chip Seal at One Year”

  1. Chip and seal is detriment for bicylists especially during the application, but even afterwards. The surface quality isn’t the same and the left over adhesive and chips adhere to tires and can cause flats.

  2. I am to make a small comment. These technologies for use different areas. Fog seal technology used successfully in low traffic volume roads. On the road’s highways, the intensive process of abrasion will lower effect technology fog seal.

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