Mechanistic flexible pavement overlay design program.

Details

• Creators:
  Wu, Zhong ; Gaspard, Kevin
• Corporate Creators:
  Louisiana Transportation Research Center
• Corporate Contributors:
  Louisiana. Dept. of Transportation and Development ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Flexible pavements
  • Overlays (Pavements)
  • Pavements, Flexible--Louisiana
  • Pavements--Overlays
  • Pavements--Testing
• Publication/ Report Number:
  FHWA/LA.08/454
• Resource Type:
  Tech Report
• Geographical Coverage:
  Louisiana
• Edition:
  Final report; Mar. 2006-Dec. 2008.
• Corporate Publisher:
  Louisiana Transportation Research Center
• Abstract:
  The current Louisiana Department of Transportation and Development (LADOTD) overlay thickness design method follows the “Component ; Analysis” procedure provided in the 1993 AASHTO pavement design guide. Since neither field nor laboratory tests are required by LADOTD for ; this method, pavement engineers usually rely on a pre-assigned parish-based typical subgrade resilient modulus value and a set of assumed layer ; coefficients for determining the effective structural number of an existing pavement in an overlay thickness design. This may lead to significant errors ; in the designed overlay thickness results because the selected design parameters do not represent actual field conditions. ; The objective of this research was to develop an overlay design method/procedure that is used for a structural overlay thickness design of flexible ; pavement in Louisiana based upon (1) in-situ pavement conditions and (2) non destructive test (NDT) methods, specifically the falling weight ; deflectometer (FWD) and/or Dynaflect. ; Fifteen overlay rehabilitation projects were selected for this study. These projects were strategically located throughout Louisiana with different ; traffic levels. At each selected project, NDT deflection tests including the falling weight deflectometer (FWD) and Dynaflect were performed at a ; 0.1-mile interval. For some of the selected projects, detailed condition survey data including cracking, rut depth, International Roughness Index (IRI), ; mid-depth temperature, and pavement thickness was also collected. Six NDT-based overlay design methods were selected and used in the overlay ; thickness design analysis. Results indicated that the 1993 AASHTO NDT procedure generally over estimated the effective structural number for the ; existing asphalt pavements in Louisiana, which would result in an under-designed overlay thickness. On the other hand, other NDT methods (i.e., ; ROADHOG, Asphalt Institute MS-17, Louisiana 1980 Deflection method, ELMOD5, and EVERPAVE) were found inapplicable to the Louisiana ; pavement conditions because all those methods rely on locally calibrated design parameters. Since further calibration of those NDT methods requires ; additional testing resources and is also considered very time-consuming, a modified FWD deflection based overlay thickness design method was ; proposed in this study. This method, based upon the Louisiana Pavement Evaluation Chart (a relation between Dynaflect deflections and the ; structural number of existing pavements) and in-situ subgrade modulus, is deemed able to directly represent Louisiana’s pavement condition. The ; cost/benefit analysis revealed that, as compared to the current LADOTD component analysis method, the proposed NDT-based overlay design ; method would potentially save millions of dollars in the flexible pavement rehabilitation in Louisiana. Therefore, before full implementation of the ; new Mechanistic-Empirical (M-E) pavement design method, the proposed NDT-based overlay design method is recommended for implementation by ; LADOTD.
  More +
• Format:
  PDF
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/18544/dot_18544_DS1.pdf
• File Type:
  [PDF - 1.92 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:da64fe4d00a9d289714ddf6187c52cd27b3148af10904ae78c3c9f9c9fe38353