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DETERMINATION OF STRUCTURAL EQUIVALENCY FACTORS OF RECYCLED LAYERS BY USING FIELD DATA

The recycling of pavement materials is an effective cost- and energy-efficient method of reconstruction. Good results can and have been obtained with recycling. Since more than 90 percent of all hard surface roads and streets in the United States are composed of asphalt mixes, the use of recycled asphalt layers in reconstructed pavements can be extensive. Cold recycling is especially suitable for use on low-volume roads due to the lower cost and usually assumed lower strength compared with hot recycling. A value for the strength of the recycled layer or the structural coefficient is important in order to design the pavement. Underdesign can lead to premature failure and corresponding high maintenance costs. Overdesign, on the other hand, can lead to the ineffective use of available funds. Asphalt cement and emulsified asphalt have traditionally been used as a binder in recycling. Another promising binder is foamed asphalt. The latter has the advantage that it can be mixed at lower temperatures than asphalt cement and it does not need curing like emulsified asphalt. During the summer of 1981, the Indiana Department of Highways built an experimental section of 9 miles (15 km) by using asphalt emulsion and foamed asphalt in cold recycling on a low-volume road. Before, during, and after construction, various tests were conducted to determine the properties of the pavement layer to be used in the determination of the structural equivalency factors of the recycled layers. These included in situ California-bearing-ratio tests, the testing of 4-in (102-mm) recycled base-course cores taken from the pavement, and Dynaflect deflection measurements. Based on layer properties obtained in these tests and pavement deflection, an elastic-layer computer program was used to determine the structural equivalency factors. The elastic moduli of the pavement layers were determined from Dynaflect deflection measurements taken at three different times. The pavement sections determined were used to calculate structural coefficients. Various criteria were used. The methodology used to determine the elastic moduli of the pavement layers and to calculate the structural coefficients is described in this paper. A wide range of coefficient values was determined with the different criteria. A range of values was selected that can be used in design. (Author)

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 122-132
  • Monograph Title: LOW-VOLUME ROADS: THIRD INTERNATIONAL CONFERENCE, 1983
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00376536
  • Record Type: Publication
  • ISBN: 0309035112
  • Report/Paper Numbers: N908
  • Files: TRIS, TRB
  • Created Date: Aug 30 1983 12:00AM