Approximately 7,000 miles of Washington state roadway are paved with chip seals. Chip seals cost less than hot mix asphalt projects and can extend the life of asphalt pavements. The chip embedment depth, or the percentage of chips embedded in the asphalt, plays a crucial role in determining the seal’s performance. Improper chip embedment can lead to raveling, flushing, and bleeding. Unfortunately, there are no specifications governing the required percentage of embedded chips, nor are there data-driven methods available to measure chip embedment depth during construction. In a previous project, the researchers demonstrated the successful use of a laser texture scanner to measure chip embedment depth, and they developed a draft specification for it. This project is collecting field performance data for chip seals that were constructed in 2022 and measured as part of that previous study. With those data the researchers will refine the specification and acceptance criteria for chip seals based on percentage of embedment to be included in the WSDOT Construction Specifications. The resulting specification and measurement method should allow WSDOT to apply chip seals more successfully and cost effectively.
Principle Investigator: Haifang Wen, Civil and Environmental Engineering, UW
Sponsor: WSDOT
WSDOT Technical Monitor: Riley Bender
WSDOT Project Coordinator: Shervin Jahangirnejad
Scheduled completion: June 2027