Maintenance and Surface Preparation Activities Prior to Pavement Preservation Treatments (2021)

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1   Pavement preservation is broadly acknowledged to provide network-wide benefits such as extending pavement life, enhancing system performance, reducing operation and main- tenance costs, and improving safety. However, the performance of each pavement pres- ervation project hinges on many factors, including good project and treatment selection, weather during or immediately after construction, skill of the construction crew placing the treatment, and compatibility and quality of materials used on the job. One project-level factor is common to the good performance of almost every preserva- tion project: the extent of necessary maintenance and surface preparation actions that are successfully completed prior to the application of the treatment. For example, before place- ment of an asphalt pavement, edge-to-edge treatment—such as a chip seal, microsurface, or thin bonded wearing course; crack sealing; partial- and full-depth patching; and surface profile corrections—may be required. Similarly, for concrete pavements, diamond grinding may be preceded by partial- or full-depth repairs (and followed by joint resealing). If needed pre-preservation maintenance activities are not performed, the expected benefits from a preservation treatment application may not be fully realized. Many references to the performance of specific pavement preservation treatments focus on the life of the treatment or the extension to the life of the pavement, but very little information is available on a combination of both the preservation treatments and the maintenance activities performed prior to the treatment to ensure its success. While such pre-treatments are not always necessary, if they are needed, they become an integral part of a successful pavement preservation project. This synthesis report documents the types of maintenance and surface preparation activities performed by DOTs before pavement preservation treatments are applied. Its purpose is to convey how agencies address maintenance and surface preparation needs before pavement preservation by exploring the following topics: • Types of maintenance and surface preparation prior to preservation on flexible- and rigid-surfaced pavements. • Methods to identify the need for maintenance and surface preparation. • Methods to complete the maintenance and surface preparation. • Agency practices to track maintenance and surface preparation. The information in this synthesis is the result of completing a literature review, under- taking an electronic survey to collect input from DOTs on their practices, and conducting follow-up telephone interviews. The electronic survey, distributed to the 50 DOT voting members of the AASHTO Committee on Maintenance, produced 45 responses (a response rate of 90%). Six agencies participated in follow-up in-depth interviews. S U M M A R Y Maintenance and Surface Preparation Activities Prior to Pavement Preservation Treatments

2 Maintenance and Surface Preparation Activities Prior to Pavement Preservation Treatments Agencies identify the need for maintenance and surface preparation prior to pavement preservation both at the local level (e.g., by district maintenance staff) and at the central office. This decision often results from a collaboration between the two. While the infor- mation collected in local surveys often triggers a recognition of the need for this mainte- nance work, such a need is increasingly determined by evaluating information gathered in regular statewide pavement evaluations, performed with automated data collection vehicles as part of an agency’s pavement management efforts. The maintenance work itself may be carried out with either in-house or contracted resources. When the preservation work is conducted in-house, the preparatory work is almost exclusively performed in-house as well. In contrast, if the preservation work is contracted out, two approaches to completing the maintenance are observed: Pre-treatment maintenance repairs are either folded into the contracted work or performed by in-house personnel. Few agencies have formal guidelines for the maintenance and surface preparation activities required prior to pavement preservation. Such guidance includes timing issues, which can be important for some combinations of maintenance and preservation. For example, the literature widely acknowledges that cracks should be sealed (and certain patches placed on asphalt-surfaced pavements) well ahead of the placement of thin preservation treat- ments such as chip seals and microsurfacing. However, this guidance is not consistently incorporated into agency programs. This lack of an explicit link between maintenance and surface preparation and the pavement preservation is less of a concern for concrete pavements. The contribution of maintenance and surface preparation conducted prior to preserva- tion is acknowledged in the findings of several studies on that specific topic. At the same time, the ability to track whether and where such maintenance is performed is inconsistent in day-to-day practice. Information about an agency’s maintenance activities and preserva- tion treatments is often recorded in different databases, if at all, and the data locations may be identified in different ways that preclude linking the two sources of information. Based on the information collected during the preparation of this synthesis, the following opportunities for future research are identified: • Improved documentation of the links between existing pavement conditions, mainte- nance and surface preparation actions, and specific preservation treatments would help improve the performance of pavement preservation. • Identification of transition thresholds to indicate that maintenance before preservation is not cost-effective would improve the execution of pavement preservation. While a pave- ment requiring too much maintenance prior to preservation is not a good candidate for pavement preservation, quantifying how much is too much would be helpful. Similarly, some preservation treatments can be placed without performing maintenance. A more quantitative approach between the maintenance quantities and the appropriateness of different preservation treatments would help define a project as true preservation, a stopgap maintenance effort, or a major rehabilitation or reconstruction project. • Additional work would demonstrate the effect on performance (both in the short term and longer term) of preservation treatments when maintenance work is not conducted and would document a process that allows agencies to analyze the impacts of failing to perform maintenance. • While beyond the scope of this study, a need remains for consistent system data inputs to construction management, maintenance management, and pavement management systems that would facilitate the sharing of mutually useful data. Those data inputs

Summary 3   would include the consistent vocabulary of preservation and maintenance treat- ments, route identification locations, work type identified, performed work amount, and needs identified but left undone. • Guidance on how pavement management systems can model preservation treatment performance based on the type and amount of preliminary maintenance and surface prep- aration work would help agencies assess the performance effects and cost-effectiveness of various pavement actions.