National Academies Press: OpenBook

Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures (2016)

Chapter: Appendix B - State Construction Engineer Survey

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Suggested Citation:"Appendix B - State Construction Engineer Survey ." National Academies of Sciences, Engineering, and Medicine. 2016. Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures. Washington, DC: The National Academies Press. doi: 10.17226/23641.
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Suggested Citation:"Appendix B - State Construction Engineer Survey ." National Academies of Sciences, Engineering, and Medicine. 2016. Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures. Washington, DC: The National Academies Press. doi: 10.17226/23641.
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Suggested Citation:"Appendix B - State Construction Engineer Survey ." National Academies of Sciences, Engineering, and Medicine. 2016. Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures. Washington, DC: The National Academies Press. doi: 10.17226/23641.
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Page 117
Suggested Citation:"Appendix B - State Construction Engineer Survey ." National Academies of Sciences, Engineering, and Medicine. 2016. Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures. Washington, DC: The National Academies Press. doi: 10.17226/23641.
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Page 117
Page 118
Suggested Citation:"Appendix B - State Construction Engineer Survey ." National Academies of Sciences, Engineering, and Medicine. 2016. Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures. Washington, DC: The National Academies Press. doi: 10.17226/23641.
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Page 119
Suggested Citation:"Appendix B - State Construction Engineer Survey ." National Academies of Sciences, Engineering, and Medicine. 2016. Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures. Washington, DC: The National Academies Press. doi: 10.17226/23641.
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Page 120
Suggested Citation:"Appendix B - State Construction Engineer Survey ." National Academies of Sciences, Engineering, and Medicine. 2016. Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures. Washington, DC: The National Academies Press. doi: 10.17226/23641.
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Page 120

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115 NCHRP 46-05 RAP and RAS—Construction Engineers Introduction This survey is collecting information about individual recycled material properties, processes, and practices. The focus is on asphalt mixtures with >25% RAP mixtures, recycled asphalt shingles (RAS) mixtures, and mixtures with a combination of RAP and RAS. The survey is organized as follows: • Recycled Materials Supply (availability) • Recycled Materials Stockpiling and Processing Practices • Testing for Asphalt Content and Aggregate Properties • Asphalt Plant Operations • Paving and Finished Mat Practice • Identification of projects for case studies (looking for successes AND failures). Respondent Information First Name: _________________________________________________ Last Name: _________________________________________________ Agency: _________________________________________________ State: _________________________________________________ E-mail Address: _________________________________________________ Phone Number: _________________________________________________ 1. Supply and Demand: Which types and percentages of recycled materials used in asphalt mixtures can be limited by the available supplies. Also, an overabundance of recycled material(s) can result in various supply-demand competitions. Please indicate if recycled materials supplies are available statewide, on a district by district basis, or only through a few local material recyclers. Also, indicate if there is any excess of recycled materials (i.e., more supply than demand). Comments: RAP Stockpiling and Processing Practices 2. Select the “retained on” sieve size used to define the coarse RAP fraction. ( ) +9.5-mm (3⁄8-in.) ( ) +4.75-mm (No. 4) ( ) +2.36-mm (No. 8) Material RAP Shingles (RAS) Recycled material is available: There is an excess of the recycle material: APPENDIX B State Construction Engineer Survey

116 3. Indicate how frequently each of the following RAP processing and stockpiling practices are used in your state. Comments: 3.a. Indicate which sieve sizes are used to fractionate RAP. (Check all that apply. If the sizes you use are not listed, you can add the sizes in the “other” boxes at the bottom of the list or in the comment box.) ( ) 19.0-mm to 4.75-mm (¾-in. to No. 4) ( ) 12.5-mm to 9.5-mm (½-in. to 3⁄8-in.) ( ) 12.5-mm to 6.4-mm (½-in. to 1/4-in.) ( ) 9.5-mm to 4.75-mm (3⁄8-in. to No. 4) ( ) 9.5-mm to 2.36-mm (3⁄8-in. to No. 8) ( ) Other: _________________________________________________ ( ) Other: _________________________________________________ Comments: 3.b. Does hot and/or wet weather affect RAP crushing and screening (e.g., build up in feeder or crushers, blind screens, stick to conveyor belts)? 3.c. What are the time constraints between processing the RAP and using it in asphalt mixture? 4. Do your current processing and stockpiling practices need to be adjusted or changed so that higher percentages of RAP can be used? If yes, please indicate what changes are needed in the comment box below. ( ) Yes ( ) No Comment Shingles (RAS) Stockpiling and Processing Practices 5. Select the maximum shingle (RAS) particle size allowed. ( ) 12.5-mm (½-in.) ( ) 9.5-mm (3⁄8-in.) ( ) 4.75-mm (No. 4) ( ) 2.36-mm (No. 8) ( ) Other: Topic Frequently Occasionally Rarely Not Applicable Don't Know RAP is processed at the asphalt plant site RAP is processed elsewhere by asphalt mix contractor and stockpiled at plant RAP is processed by third party and delivered to asphalt mix contractor Large quantity of RAP collected, then processed Coarse RAP stockpile is fractionated Fine RAP stockpile is fractionated Asphalt mix contractor required to have sufficient processed RAP material stockpiled at the beginning of the construction project Weather impacts RAP crushing and sizing operations (e.g., clumping, blinding screens, etc.) We have time limitations between RAP processing and using Sand is added during processing or after processing to prevent clumping Unprocessed stockpiles are covered Stockpiles are stored in covered areas only covered after processing

117 6. Indicate how frequently each of the following shingles (RAS) processing and stockpiling practices are used in your state. Comments: 6.a. Does hot and/or wet weather affect shingles (RAS) crushing and screening (e.g., build up in feeder or crushers, blind screens, stick to conveyor belts)? 6.b. What are the time constraints between processing the shingles (RAS) and using it in asphalt mixture? 7. Do your current processing and stockpiling practices need to be adjusted or changed so that RAS or combinations of RAP/RAS can be more widely used? If yes, please indicate what changes are needed in the comment box below. ( ) Yes ( ) No Comments: Additional Contacts with Experience 8. We would like to collect specific information on plant and paving modifications which may be needed to work with high RAP mixtures, shingles, and/or a combination of RAP/RAS. Please provide contractor contact information below. The contractor’s experience does not have to be on state projects. Contractor with experience using > 25% RAP (company, name, phone, and/or e-mail). Contractor with experience using shingles RAS (company, name, phone, and/or e-mail). Contractor with experience using a combination of RAP and RAS (company, name, phone, and/or e-mail). Topic Frequently Occasionally Rarely Not Applicable Don't Know RAS is processed at the asphalt plant site RAS is processed elsewhere by asphalt mix contractor and stockpiled at plant Manufacturing waste and tear offs are kept separate RAS is processed by third party and delivered to asphalt mix contractor Large quantity of RAS collected, then processed Asphalt mix contractor required to have sufficient processed RAS material stockpiled at the beginning of the construction project Weather impacts RAS crushing and sizing operations (e.g., clumping, blinding screens, etc.) We have time limitations between RAS processing and using Sand is added during processing or after processing to prevent clumping Unprocessed stockpiles are covered Stockpiles are stored in covered areas only covered after processing

118 QC/QA Testing and Assumptions 9. Indicate what tests or assumptions are used to determine asphalt content, aggregate properties, and other material or mixture properties are determined. (Check all that apply.) Comments: 9.a. What test method is used for determining recycled material or mixture with recycled material specific gravity? 9.b. Briefly describe how moisture content is determined. That is, how dried (microwave, oven, air dry, rapid drying technology), temperature, definition used to determine “dry” or the maximum allowable moisture content. 9.c. What contaminates are assessed? How is the presence of contaminates determined (e.g., visual observation, testing, etc.)? 9.d. What extraction method (e.g., centrifuge, reflux, vacuum) and solvent is used? Testing RAP Shingles (RAS) Recycled Material Properties Certified by Supplier Recycled Material Properties Estimated Asphalt Mix with Recycled Materials Is Tested Bulk specific gravity Theoretical maximum specific gravity (i.e., Rice method; AASHTO T209) Moisture content Contaminates Ignition oven asphalt content Ignition oven gradation Solvent extraction asphalt content Solvent extraction gradation Flat and elongated aggregate properties from recycled materials Fine aggregate angularity of aggregates from recycled materials

119 Asphalt Plant Operations 10. Indicate if any of the following are seen or adjustments are needed when using higher than typical RAP% mixtures, RAS mixtures, or a combination of RAP/RAS mixtures on asphalt plant operations. (Check all that apply.) Comments: 10.a. What can be done to minimize non-uniformity of recycled materials as they are added to the plant? 10.b. What are the plant temperature constraints? 10.c. What are the time constraints on silo storage time(s)? Topics > 25% RAP% Shingles (RAS) Combination of RAP/RAS No Difference from Conventional Mixtures Don’t Know Recycled material stockpile crusting, clumping, and bridging of materials influence handling and feeding into plant Additional cold feed bins are used to meet the required recycled material gradation Recycled materials screened and sized as it is fed into asphalt plant Separate dryer drum used to dry recycled materials Difficult to obtain uniform feed of recycled materials Adjustments of either metering methods or sensors are needed to properly measure small percentages of recycled materials In-line crushing and sizing is used (i.e., recycled material is processed as it is added to the plant) Point of introduction of the recycled material into the plant needs to be changed (e.g., RAP collar relocated closer to the drum discharge point or the recycled material fed directly into pugmill at batch plant) Production rates need to be slowed (e.g., extra drying time needed) Plant temperatures need to be LOWERED when using recycled materials Plant temperatures need to be RAISED when using recycled materials MINIMUM silo storage times are needed MAXIMUM silo storage times are needed Difficult to obtain mixture uniformity Mixes with recycled material content tend to segregate more frequently during load out

120 Paving Operations 11. When placing asphalt mixtures with more than 25% RAP, how frequently each of the following is observed. 12. When placing asphalt mixtures with shingles (RAS), how frequently each of the following is observed. 13. When placing asphalt mixtures with a combination of RAP and shingles (RAS), how frequently each of the following is observed. 13.a. What word or words would you use to describe the flow of mixture from haul truck to hopper as “different”? 13.b. What problem(s) with the finished mat is (are) associated with crusting of the windrow? Topic Always Often Sometimes Rarely Never Don't Know Stiffer mixtures flow differently from end dump haul truck to paver hopper Crusting of mixtures when deposited in windrows can be a problem (e.g., clumps deposited into hopper) Mix in paver wings more likely to build up and form crust on top Visible "lines" in the direction of paving more noticeable between screed and extension Uniformity and density at the joint is more difficult to obtain Hand work is more difficult Mixtures are more likely to segregate Topic Always Often Sometimes Rarely Never Don’t Know Stiffer mixtures flow differently from end dump haul truck to paver hopper Crusting of mixtures when deposited in windrows can be a problem (e.g., clumps deposited into hopper) Mix in paver wings more likely to build up and form crust on top Visible "lines" in the direction of paving more noticeable between screed and extension Uniformity and density at the joint is more difficult to obtain Hand work more difficult Mixtures are more likely to segregate Topic Always Often Sometimes Rarely Never Don't Know Stiffer mixtures flow differently from end dump haul truck to paver hopper Crusting of mixtures when deposited in windrows can be a problem (e.g., clumps deposited into hopper) Mix in paver wings more likely to build up and form crust on top Visible "lines" in the direction of paving more noticeable between screed and extension Uniformity and density at the joint is more difficult to obtain Hand work more difficult Mixtures are more likely to segregate

121 14. Determining finished mat properties. Number of gyrations used to prepare samples for lab density testing: _ 14.a. Density testing of the finished mat: ( ) Nuclear density gauge ( ) Non-nuclear gauge ( ) Cores 14.b. Do any of the recycled materials seem to influence the non-destructive test results? ( ) Yes ( ) No ( ) Maybe Comments: 14.c. If smoothness is a pay item, do the recycled materials make it more difficult to meet the requirements or to obtain incentives? ( ) Yes ( ) No ( ) Maybe Comments: 14.d. Check the box if it is more difficult to obtain acceptable properties (within specification limits) when compared with similar mixtures without any recycled material content. Comments: 15. What do field inspectors need to look for when evaluating mixtures with high recycled RAP content, RAS, or combinations of RAP and RAS? 16. Do you have a project that you would like to have considered for a case study? The project can be one which worked well, was a disaster (major learning lessons), or anywhere in between. If so, please provide contact information (name, project name/ location, email, phone). Any projects identified as “not successful” will be diplomatically and generically framed to provide information on lessons learned. Volumetric Property 25% or More RAP Shingles (RAS) RAP and RAS Combination Mixtures Air Voids, % VMA. % VFA, % Dust to Asphalt Ratio

Next: Appendix C - Responding Agencies »
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TRB's National Cooperative Highway Research Program (NCHRP) Synthesis 495: Use of Reclaimed Asphalt Pavement and Recycled Asphalt Shingles in Asphalt Mixtures summarizes current practices for the use of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) in the design, production, and construction of asphalt mixtures. It focuses on collecting information about the use, rather than just what is allowed, of high RAP, RAS, and/or a combination of RAP and RAS.

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