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 is to develop recommended guidance for the construction of sand seals and UTBWCs as used in preservation treatments.
PHASE I: (1) Collect and review relevant domestic and foreign literature, research findings, and information relative to the construction of sand seals and UTBWCs as used in preservation treatments. This information may be obtained from published and unpublished reports, survey of state and local transportation agencies, and contacts with transportation agencies, industry, and other public and private organizations. Identify material of relevance for the development of guide specifications for further consideration in this research. (2) Prepare an updated, detailed work plan for Phase II that includes a process for developing separate guidance for (1) sand seals and (2) UTBWCs. It is expected that the guidance will address practices applicable to different parts of the United States and the variety of materials used; methods of construction and quality assurance; methods of measurement, warranty, and payment; and other relevant items with consideration to performance. (3) Prepare an interim report that documents the research performed in Tasks 1 through 3. Following review of the interim report by the NCHRP, the research team will be required to make a presentation to the project panel. Work on Phase II of the project will not begin until the interim report is approved and the Phase II work plan is authorized by the NCHRP. The decision on proceeding with Phase II will be based on the contractor’s documented justification of the updated work plan.
PHASE II: (4) Execute the plan approved in Task 3. Based on the results of this work, prepare the recommended guidance for sand seals and UTBWCs in an appropriate format for consideration by the AASHTO Committee of Materials and Pavements. (5) Prepare material, in a PowerPoint or other format, for use in webinars and presentations to facilitate implementation of the research findings. The material shall (1) identify the features of the guidance and anticipated user benefits and (2) include key notes and details to facilitate use by interested parties. Also prepare a stand-alone technical memorandum titled “Implementation of Research Findings and Products”. (6) Prepare a final deliverable that documents the entire research effort. The deliverable will include (1) a research report documenting the work performed in the project and used to develop the guidance, (2) the recommended guidance, (3) presentation material, and (4) technical memorandum on implementation.
STATUS: Research in progress.