Two-lift construction -- placing binder and top courses over either a base course or existing pavement -- has long been accepted practice. New York State 1973 specifications required that all paving in upstate counties be completed before October 15, and that the binder course not be exposed over the winter. This places the contractor in a precarious situation. Pavement construction scheduling may require placing the top course after this deadline. By the time the base is placed, the construction season is generally into late September or early October, after which the binder is placed (provided no adverse weather conditions occur), thus carrying construction into late September or early October. The contractor has perhaps one to three weeks to place top course if the weather is acceptable; this is often impossible. Eliminating the binder would help alleviate this problem. Placing a thicker top course in one lift would help heat retention and possibly contribute to higher densities and lower void contents, and the paving deadline could be extended. Field experiments reported here show this to be true. Pavement roughness was of special concern because the binder is also known as a 'shim' course; its elimination might create a rougher riding surface. The average driver, however, cannot discern any appreciable changes in roughness because these are so slight. The thick-lift wearing course provided a denser pavement and was much more efficient to place.

Media Info

  • Pagination: 22 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00153985
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: NYSDOT-ERD-77-RR-41
  • Created Date: Jun 17 1977 12:00AM