Design and construction recommendations for thin overlays in Texas.

Details

• Creators:
  Wilson, Bryan ; Scullion, Tom ; Estakhri, Cindy
• Corporate Creators:
  Texas A&M Transportation Institute
• Corporate Contributors:
  United States. Federal Highway Administration
• Subject/TRT Terms:
  • Overlays (Pavements)
  • Hot mix paving mixtures
  • Specifications
  • Slurry seals
  • Fine aggregates
  • Stone matrix asphalt
  • Recycled materials
  • Mix design
  • Dense graded aggregates
  • Rutting
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• Publication/ Report Number:
  FHWA/TX-13/0-6615-1
• Resource Type:
  Tech Report
• Geographical Coverage:
  Texas
• Corporate Publisher:
  Texas. Dept. of Transportation. Research and Technology Implementation Office
• NTL Classification:
  NTL-HIGHWAY/ROAD TRANSPORTATION-Pavement Management and Performance ; NTL-HIGHWAY/ROAD TRANSPORTATION-Design
• Abstract:
  Thin HMA overlays, laid at 1.0 inch or thinner, are cost-effective surface maintenance options. The primary focus of this research was ; to develop specifications for three such mixes: fine dense-graded mix (fine DGM), fine-graded stone matrix asphalt (fine SMA), and ; fine-graded permeable friction course (fine PFC). A number of slurry overlay systems were also evaluated, but to a lesser extent. ; Draft specifications for the three mix types were first developed based on the results of a literature/information search and a ; field investigation of 11 existing projects. The specifications included minimum material quality levels, laboratory performance ; criteria, and construction recommendations. To evaluate the design recommendations, extensive laboratory testing was performed on ; each of the three thin overlay mixes with five different aggregates. Of the 15 mixes attempted, 12 had acceptable designs in terms of ; the specified performance tests. For the most part, the draft specifications appeared to function well with minor alterations ; recommended. Testing also included two supplementary studies on the effects of screening type in fine SMA and the effects of ; recycled materials on both the fine SMA and fine PFC. Compaction of the fine SMAs was highly influenced by packing ; characteristics of the coarse and fine aggregates. Screening quality did not affect fine SMA rutting resistance, but did affect cracking ; resistance. Using recycled aggregates reduced rutting problems but increased cracking susceptibility; however, most mixes performed ; well suggesting that quality, well-engineered mixes can still have good performance when recycled materials are used in limited ; amounts. ; Concerning laboratory testing of slurry overlays, the applicability of the overlay tester/procedures and the three-wheel ; polishing device in testing should be further studied. In particular, a tie-in with actual field performance should be identified, perhaps ; with the Accelerated Pavement Test program. ; Six thin overlay projects, comprising 10 unique mix designs, were constructed and evaluated. Most projects were constructed ; without problems, though some encountered issues with over- and under-compaction. Initial performance has been very good, ; although, since all the sections are less than two years old, the long-term performance is still undetermined. ; The researchers recommend adapting the specifications accompanying this report, which require using high quality materials ; and passing strict laboratory performance tests on both the lab design and trial batch materials. They do not recommend incorporating ; recycled materials in these mixes, though preliminary results are promising. Guidelines for pavement evaluation and mix selection ; were also prepared, which recommend the use of certain thin overlay or slurry overlay options given the pavement, traffic, and climate ; conditions.
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• Format:
  PDF
• Funding:
  Project 0-6615
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/26365/dot_26365_DS1.pdf
• File Type:
  [PDF - 17.82 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:ee42a11687c17167b907b68ae09ad1ce334ad4e8ba51065a671ed07a3b85b78a