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Crack seal--Product used to fill individual pave- Pavement preventive maintenance--Planned ment cracks to prevent entry of water or other non- strategy of cost-effective treatments to an existing compressible substances such as sand, dirt, rocks, and roadway system and its appurtenances that preserves weeds. the system, retards future deterioration, and main- Diamond grinding--The process of removing tains or improves the functional condition of the sys- a thin layer of existing concrete pavement surface by tem (without increasing the structural capacity). grinding it with a machine that has a series of closely Pavement rehabilitation--Work undertaken to spaced rotating diamond saw blades. extend the service life of an existing pavement. This Dowel bar retrofit--A method of reinforcing includes the restoration, placing an overlay, and/or cracks in highway pavement by inserting steel dowel other work required to return an existing roadway to bars in slots cut across the cracks. a condition of structural and functional adequacy. Dust palliative--A highly diluted petroleum Regrade/regravel--A process similar to "gravel emulsion sprayed on an unpaved surface to control grading" defined earlier, but including the entire direct particulate matter emissions (commonly called length of a given road project. "road dust") from unpaved roads and other surfaces Shot blasting--A process that restores the micro- with vehicle and machinery traffic. texture and macrotexture of both asphalt and concrete Fog seal--A light application of a diluted, slow- pavement surfaces by abrading it with steel shot. The setting asphalt emulsion to the surface of an aged process includes a magnetic system that collects and pavement surface. recycles the expended shot and a vacuum system Gravel blading--The process of spreading small that collects the residue for disposal. amounts of gravel on localized areas of unpaved roads Slurry seal--Mixture of emulsified asphalt, to fill holes, restore ride quality, and reestablish the water, well-graded fine aggregate, and mineral transverse geometry (commonly called the "crown") filler that has a creamy, fluid-like appearance when to facilitate drainage. applied. Hot patches--Pothole and other pavement defect Spread millings--The use of recycled asphalt repair made with hot-mix asphalt pavement millings to maintain gravel roads. The Joint seal--Joint seals, seal expansion, and con- millings are used in place of virgin aggregate. traction joints in concrete. Thin overlay--A layer of new pavement that Microsurfacing--A polymer-modified cold-mix is laid on the existing surface for purposes of paving system that can remedy a broad range of prob- restoring surface characteristics with no intention lems on today's streets, highways, and air fields. This of enhancing the structural capacity of the under- is a mixture of dense-graded aggregate, asphalt emul- lying pavement. These are usually less than 1.5 in. sion, water, and mineral filler. (3.75 cm) thick. Mud jacking--Process of pumping a water, dirt, Thin portland cement concrete overlay--A thin and cement mixture under concrete slabs in order to overlay consisting of portland cement concrete (com- lift it. monly called "white-topping"). Otta seal--A low-cost type of road surface, usu- Thin hot mix asphalt overlay--A thin overlay ally a 1630-mm-thick mixture of bitumen emulsion consisting of hot mix asphaltic concrete (commonly and well-graded crushed rock. called "black-topping"). Otta seal (New Zealand)--Low-cost type of road surface, usually a 1630-mm-thick mixture of APPENDICES A AND B recycled motor oil (commonly called "Norwegian road oil") and well-graded crushed rock. Appendices A and B as submitted by the con- Pavement preservation--The sum of all activ- sultant are not published herein. These appendices ities undertaken to provide and maintain serviceable are available as part of the web version of this roadways. This includes corrective maintenance and document at: preventive maintenance, as well as minor rehabilita- NCHRPResearchResultsDigests.aspx, see Research tion projects. Results Digest 365. 26

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Transportation Research Board 500 Fifth Street, NW Washington, DC 20001 ISBN 978-0-309-22349-2 90000 Subscriber Categories: Environment Highways Maintenance and Preservation 9 780309 223492 These digests are issued in order to increase awareness of research results emanating from projects in the Cooperative Research Programs (CRP). Persons wanting to pursue the project subject matter in greater depth should contact the CRP Staff, Transportation Research Board of the National Academies, 500 Fifth Street, NW, Washington, DC 20001. COPYRIGHT INFORMATION Authors herein are responsible for the authenticity of their materials and for obtaining written permissions from publishers or persons who own the copyright to any previously published or copyrighted material used herein. Cooperative Research Programs (CRP) grants permission to reproduce material in this publication for classroom and not-for-profit purposes. Permission is given with the understanding that none of the material will be used to imply TRB, AASHTO, FAA, FHWA, FMCSA, FTA, or Transit Development Corporation endorsement of a particular product, method, or practice. It is expected that those reproducing the material in this document for educational and not-for-profit uses will give appropriate acknowledgment of the source of any reprinted or reproduced material. For other uses of the material, request permission from CRP.