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From page 132...
... 132 Best Practices for RAP Management I Purpose of this Guide This document provides guidance for management of reclaimed asphalt pavement (RAP)
From page 133...
... 133 Recent surveys have reported that across the United States, the average RAP content in new asphalt mixes is around 12 to 15%. A goal established by the National Asphalt Pavement Association (NAPA)
From page 134...
... 134 • Avoids filling up curbs and avoids drop-offs at drainage inlets in urban settings, • Reduces the need for the costly addition of shoulder material along the edge of pavements on rural roadways, • Restores pavement grades and profiles, which are important for smoothness, • Leaves a rough texture on the remaining surface that creates a very good bond with an overlay, and • Is an efficient removal process that can be done within a short lane-closure with the paving operations. Selecting the Milling Depth Selection of the milling depth is a critical agency decision in planning the rehabilitation of a pavement.
From page 135...
... 135 Finally, the milled surface should be inspected for uniform texture. See Figure 3.
From page 136...
... 136 A special milling operation may also be beneficial when it is desirable to mill the surface layer in one pass and the underlying layer(s) in a second pass because the surface-course millings contain a high-value friction aggregate and/or a modified binder.
From page 137...
... 137 contents. Another form of waste is mix rejected from a project due to incomplete coating or due to the mix temperature being too high or too low for the job.
From page 138...
... 138 Inventory Analysis RAP management should begin with a basic inventory analysis of available RAP and mix production. This analysis is important to establish realistic goals for how much RAP can be used at a particular plant.
From page 139...
... 139 cally, the contractor was able to use only about 15 percent RAP with the old plant, but the new plant was advertised to handle up to 50 percent RAP. Annual tonnage for the city work has been about 30,000 tons, commercial work has been about 30,000 tons, and state work about 110,000 tons.
From page 140...
... 140 this practice with the stipulations that the combined blend of RAP and virgin aggregates meet the appropriate Superpave consensus aggregate requirements and the volumetric properties of the recycled mix design meet all of the standard asphalt mix specifications. When this approach is used, good processing practices of the multiple-source RAP material are necessary to create a uniform material.
From page 141...
... 141 material from the roadway, it is best to minimize further crushing of milled RAP whenever possible. Therefore, when a contractor obtains a large quantity of millings from a single project, it is considered a best practice not to further crush this material, but rather to use it "as-is" in mix designs or to screen the millings to remove large particles.
From page 142...
... 142 Screening RAP during Processing Since crushing RAP will create more aggregate fines, it is best to set up the crushing operation so that the RAP is screened before it enters the crusher. This will allow the finer RAP particles that pass through the screen to bypass the crusher.
From page 143...
... 143 blind screens, and RAP fines will stick to belts and accumulate under conveyors. Not only does this require more maintenance of RAP processing units and RAP feeder systems for mix production, it can also affect the gradation and asphalt content of the RAP.
From page 144...
... 144 3. Does your plant have an excess amount of RAP (i.e., the quantity of RAP stockpiled exceeds RAP usage per year)
From page 145...
... 145 Figure 12. Covered stockpile to minimize moisture in RAP.
From page 146...
... 146 IV. Sampling and Testing the RAP This section provides guidance on the best methods and practices for sampling and testing RAP as part of a quality management program.
From page 147...
... 147 that will comprise a large portion of an asphalt mixture. A minimum of 10 tests should be performed on a RAP stockpile to yield good statistics for consistency analyses.
From page 148...
... 148 1 2 3 4 5 6 7 8 Figure 15. Steps for the best method to sample RAP.
From page 149...
... 149 A recent joint study by the University of Nevada-Reno and NCAT examined several options for testing RAP to determine the best methods for determining many of the properties noted above. Three methods were used to determine asphalt contents and recover the aggregates for aggregate property tests: the ignition method, the centrifuge extraction method, and the reflux extraction method.
From page 150...
... 150 ignition oven temperature to minimize this problem. However, in some cases, agencies have elected simply to use other methods for determining asphalt contents and recovering aggregates for asphalt mixes in their jurisdiction.
From page 151...
... 151 where Pba (asphalt absorption) also has to be assumed based on historical records of mixes with the same raw materials.
From page 152...
... 152 If the variability of one or more properties exceeds the values in Table 2, the stockpile management guidelines in this document may be helpful in reducing the standard deviations. Also keep in mind that sampling practices can have a significant effect on variability results.
From page 153...
... Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) NASA National Aeronautics and Space Administration NASAO National Association of State Aviation Officials NCFRP National Cooperative Freight Research Program NCHRP National Cooperative Highway Research Program NHTSA National Highway Traffic Safety Administration NTSB National Transportation Safety Board PHMSA Pipeline and Hazardous Materials Safety Administration RITA Research and Innovative Technology Administration SAE Society of Automotive Engineers SAFETEA-LU Safe, Accountable, Flexible, Efficient Transportation Equity Act: A Legacy for Users (2005)

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