Standardizing Lightweight Deflectometer Measurements for QA and Modulus Determination in Unbound Bases and Subgrades

The primary objective of this study is to provide State Departments of Transportation (DOTs) and local government engineers with a practical and theoretically sound methodology for the evaluation of in-place elastic modulus of unbound layers, subgrades, and other earthwork from Lightweight Deflectometer (LWD) field test data. This will require the development of techniques to fully account for: (1) the influence of moisture suction pressures on LWD measurements; (2) the differences in the LWD induced stress states/strain levels and the stress states/strain levels induced by construction equipment and long term traffic loads; and (3) the effects of layering on LWD measurements when testing on finite-thickness layers (e.g., base or subbase over subgrade) vs. half-space conditions (e.g., subgrade). The test standards and analysis methodologies developed in this study will enable agencies to: (a) use LWDs with confidence for construction quality assurance (QA); (b) develop catalogs of appropriate design modulus values for use in pavement structural design, specifically in the Mechanistic-Empirical Pavement Design Guide, (MEPDG) and its companion DARWin-ME software; and (c) reduce recurring annual costs associated with QA inspection of soils and unbound materials.


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Filing Info

  • Accession Number: 01541241
  • Record Type: Research project
  • Source Agency: Federal Highway Administration
  • Contract Numbers: TPF-5(285)
  • Created Date: Oct 21 2014 1:01AM