BACKGROUND: Pavement preservation provides a means for maintaining and improving the functional condition of an existing highway system. Although pavement preservation is not expected to substantially increase structural capacity, it generally leads to improved pavement performance and longer service life. Sand seals are used to fill existing pavement cracking and even out surface smoothness defects. Ultra-thin bonded wearing courses (UTBWCs) are used to correct surface distresses, and improve surface smoothness and friction, and reduce hydroplaning. Although a great deal of information on the design, materials, and construction practices of these treatments is available, there is no nationally accepted guidance on their construction. There is a need to develop guidance to help state departments of transportation (DOTs) apply these treatments more effectively and achieve the most benefit of their applications.

OBJECTIVE: The objective of this research was to develop recommended guidance for the construction of sand seals and UTBWCs as used in preservation treatments.

STATUS: Research is complete. The final deliverable included 3 documents: (1) guidance on the construction of sand seals and ultra-thin bonded wearing courses, guidance on the quality assurance of sand seals and ultra-bonded wearing courses, an (3) a final report that summarizes the work performed in the project. The guidance documents for construction and quality assurance have been provided to AASHTO Committee on Materials and Pavements for consideration and adoption. The contractor's final report is available at 

https://www.nationalacademies.org/webdocs/14-48parti-finalreport/14-48PartI-FinalReport.pdf?channelToken=b9515dcea9b44b1caeec286a25accf32&download=false&tStamp=1713982764848