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 is 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.
RESEARCH PLAN: (1) Identify the properties of unbound pavement layers required for pavement design and analysis in accordance with Pavement ME Design procedures, and the data elements required for their estimation. (2) Review the content of the LTPP database, and discuss availability of the data elements identified in Task 1. (3) Assess the adequacy of the data elements available in the LTPP database for estimating the material properties identified in Task 1, and (2) evaluate the feasibility of using available LTPP data for developing valid relationships between laboratory- and field-derived properties of unbound materials. The assessment shall address data quantity, ranges, quality, and other relevant features. If required, identify means for dealing with data shortage and other deficiencies (e.g., acquiring data from other sources, conducting additional laboratory or field tests, or removing some data). (4) If found feasible, propose a plan for using the data available in the LTPP database to develop relationships between laboratory- and field-derived properties of unbound layers required for pavement design and analysis. The plan shall provide specific information on the different aspects of the required data elements (e.g., type, quantity, and quality), and present a detailed and specific approach for developing these relationships. (5) Prepare a final deliverable that documents the entire research effort. All relevant data sets identified in this research (including those available from LTPP database and other sources) shall be provided, in an electronic format with schema, as an attachment to the final deliverable.
STATUS: Research started on June 12, 2018.