Design and performance evaluation of very thin overlays in Texas.

Details

• Creators:
  Scullion, Tom ; Zhou, Fujie ; Walubita, Lubinda ; Sebesta, Stephen
• Corporate Creators:
  Texas Transportation Institute
• Corporate Contributors:
  Texas. Dept. of Transportation. Research and Technology Implementation Office
• Subject/TRT Terms:
  • Pavements
  • Asphalt pavements
  • Overlays (Pavements)
  • Rutting
  • Cracking
  • Skid resistance
  • Ground penetrating radar
  • Infrared detectors Pavements--Texas--Overlays
  • Asphalt concrete
• Publication/ Report Number:
  FHWA/TX-09/0-5598-2
• Resource Type:
  Tech Report
• Geographical Coverage:
  Texas
• Edition:
  Technical report; Sept. 2007-Aug. 2008.
• Corporate Publisher:
  Texas Transportation Institute
• Abstract:
  Very thin overlays 1-inch thick or less were placed as surface layers on five major highways in Texas. ; These mixes were designed in the laboratory to have a balance of good rut resistance as measured by ; TxDOT’s Hamburg Wheel Tracking test and good reflection cracking resistance as measured by TTI’s ; Overlay Tester. These Crack Attenuating Mixes (CAM) were designed and constructed based on a new ; special specification SS 3109. In the design phase the optimal asphalt content was initially determined using ; the Superpave Gyratory Compactor selecting the asphalt content that achieved 98% density after 50 ; gyrations. This approach worked well with stiff binders and top quality granite aggregates. However design ; problems were encountered with the transition to softer binders and locally available materials. The ; researchers proposed an alternative design procedure where the performance tests are run first at a range of ; asphalt contents and a window defined where both rutting and crack resistance requirements are met. ; The CAM mixes designed have 100% passing the 3/8-inch sieve and binder contents ranging from 7 to 8.3% ; asphalt. Few construction problems were identified; these fine mixes are easy to compact and finish. ; However, on one project thermal segregation problems were identified which caused low density pockets ; and areas of raveling. Initial performance even over jointed concrete has been good, and skid resistance ; measurements looked very reasonable. ; The CAM mixes cost approximately 25% per ton more than the traditional mixes, but as they are placed as 1-inch ; thick mats rather than 2-inch thick, there is a clear economic advantage of using these high quality materials. TxDOT ; is in the process of updating SS 3109, and a statewide specification is scheduled for release in early 2009.
  More +
• Format:
  PDF
• Funding:
  0-5598
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/16761/dot_16761_DS1.pdf
• File Type:
  [PDF - 3.90 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:14e0df4941265dbf270ba2d17f5a20037c7f2abb2926648799d307ea1bf0407f263c3a0e4e94671a68384e9a315fb955245ec7e9be22acf00e169c462660da85