Long-term aging of recycled binders.

Details

• Creators:
  Ali, Hesham ; Mohammadafzali, Mojtaba
• Corporate Creators:
  Florida International University. Dept. of Civil and Environmental Engineering
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Asphalt pavements
  • Recycled materials
  • Rehabilitation (Maintenance)
  • Aging (Materials)
  • Durability
  • Bituminous binders
  • Pavement performance
  • Cracking
• Publication/ Report Number:
  BDV29 Two 977-01
• Resource Type:
  Tech Report
• Geographical Coverage:
  Florida
• Corporate Publisher:
  Florida. Dept. of Transportation. Research Center
• Abstract:
  Asphalt pavement is America’s most recycled material. Eighty million tons of asphalt, nearly 80% of all milled asphalt pavement, ; is recycled every year 1. To effectively maintain its 40,000 miles of paved roads, the Florida Department of Transportation ; continues to refine its maintenance and rehabilitation methods. Hot in-place recycling is a rehabilitation method with recognized ; financial and environmental benefits when used properly. The primary concern with this method is the longevity of the recycled ; pavement. Aging of the recycled binder has a strong impact on the durability of the pavement. ; Asphalt binders harden with age and become prone to cracking. Rejuvenators are added to hard asphalt to enhance its rheological ; properties. Traditional methods that evaluate the effectiveness of binder rejuvenation only examine the early performance. ; However, the recycled asphalt should have acceptable long-term performance. The pavement might crack prematurely if the ; asphalt binder ages quickly. This research looks beyond early performance and evaluates long-term aging of recycled asphalt ; binders and compares it with that of virgin asphalt. ; Aging rates of recycled asphalt binders, rejuvenated by five different commercially available products, were studied and compared ; with the aging rate of the virgin binder. These rejuvenators were selected through a screening process based on their softening ; power and other considerations. The Pressure Aging Vessel (PAV) was used to simulate aging, and the high temperature ; Performance Grade (PG) was implemented to characterize the level of aging. The cracking resistance of recycled asphalt mixes ; was evaluated using the Texas Overlay Test. The change in the mix crack resistance over time was evaluated using the Accelerated ; Pavement Weathering System. ; The results showed a significant difference in the long-term aging of samples recycled with different recycling agents. While some ; samples aged significantly slower than the virgin binder, others aged faster. Analysis of the aging rates of binders revealed that ; selecting a proper recycling agent can extend the service life up to nine years. In contrast with original binders, the aging rate of ; recycled binders did not decrease significantly after the first 20 hours of PAV exposure. Therefore, even when recycled binders ; pass PG requirements, they might be less durable than virgin asphalt. Mix tests showed that rejuvenated mixes generally have a ; better initial fatigue and reflective cracking resistance than new mixes. However, their cracking resistance might drop faster over ; the pavement life. ; The knowledge obtained from this study identified approaches to evaluate long-term aging of recycled binders. Performing a ; durability test, limiting the aging rate, and increasing PAV exposure time are the three proposed alternative procedures. These ; procedures can be used to modify the specifications so that the longevity of the recycled asphalt is considered.
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• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/29514/dot_29514_DS1.pdf
• File Type:
  [PDF - 3.34 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:35a1235e26bd8d7e5edfa18cc0d067e6f936e0496696cf0dcb30c56e94ab4504