BACKGROUND: The AASHTOWare Pavement ME Design (formerly DARWin-ME) and the AASHTO Mechanistic-Empirical Pavement Design Guide Manual of Practice (MEPDG) provide a methodology for the analysis and performance prediction of new and rehabilitated pavements. The performance of these pavements is known to be influenced by the properties of the unbound layers in the pavement structure.  These properties are often obtained from laboratory tests whose results do not always match those derived from field tests performed on the constructed layers. This difference will lead to inaccurate performance prediction and deficient design. There is a need to establish relationships between laboratory- and field-derived properties that can be used to obtain improved prediction of performance and design. 

Over the years, the LTPP Program has collected laboratory- and field-derived data that are housed in the LTPP database (available at https://infopave.fhwa.dot.gov/) and could be used to develop relationships between laboratory- and field-derived properties.  However, there is a concern about the adequacy of available LTPP data to accomplish this task.  Therefore, there is a need to assess the feasibility of using LTPP data for developing relationships that are appropriate for use in conjunction with the Pavement ME Design procedures to improve performance prediction and design.  The findings of this assessment will help make a decision regarding the need for further research. 

OBJECTIVE: The objective of this research was to evaluate the feasibility of using LTPP data for developing relationships between laboratory- and field-derived properties of unbound materials used in pavements.  The research shall be limited to those properties required for pavement design and analysis, in accordance with Pavement ME Design procedures.

STATUS: Research complete. The contractor's final report (including an addendum to the report) is available as  

https://onlinepubs.trb.org/Onlinepubs/nchrp/docs/NCHRP20-5019FinalReportwithAddendum.pdf