Synthesis of Information Related to Highway Problems. Topic 38-09. Estimating Stiffness of Subgrades and Unbound Materials for Pavement Design

<font size="4">The new Mechanistic Empirical Pavement Design Guide (MEPDG) developed under NCHRP Project 1-37A, as well as most existing methods of pavement design such as the 1993 AASHTO Guide use resilient modulus as the primary input parameter when describing subgrade, subbase, and base support characteristics. However, very few pavement designs are based on laboratory measured or field back-calculated resilient modulus values. Many agencies believe that laboratory resilient modulus testing is either too complicated, unreliable, or expensive to perform on a routine basis. Back-calculation of resilient modulus in the field has its own problems, including poor agreement with corresponding laboratory measured values. </font><font size="4">In many cases, pavement designers either simply assume resilient modulus values or use various predictive or correlation methods to provide this input. For over 30 years researchers and practitioners have been developing methods to predict laboratory resilient modulus via correlations with soil strength parameters such as unconfined compressive strength, Dynamic Cone Penetrometer, California Bearing Ratio, Hveem Stabilometer R-value, etc. or empirical relationships with soil descriptive properties such as grain size, Atterberg limits, moisture content, density, soil classification and so on. Although a large number of these empirical correlations currently exist, their accuracy and robustness are highly variable and generally unknown to the pavement designer who is using them. </font><font size="4">This synthesis will provide a summary of existing predictive correlations for resilient modulus and their appropriate usage in pavement design. Known advantages and disadvantages of direct measurement of resilient properties through sampling and testing programs as well as back-calculation will be listed and discussed along with the various empirical correlations. This synthesis will assist pavement designers in evaluating direct measurement versus empirical correlation and in evaluating the quality of the various empirical correlations available. </font><br /><br />

Language

  • English

Project

  • Status: Completed
  • Funding: $30000.00
  • Contract Numbers:

    Project 20-05, Topic

  • Sponsor Organizations:

    Federal Highway Administration

    1200 New Jersey Avenue, SE
    Washington, DC  United States  20590

    American Association of State Highway and Transportation Officials (AASHTO)

    444 North Capitol Street, NW
    Washington, DC  United States  20001

    National Cooperative Highway Research Program

    Transportation Research Board
    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Project Managers:

    Williams, Jon

  • Performing Organizations:

    Transportation Research Board

    500 Fifth Street, NW
    Washington, DC  United States  20001
  • Start Date: 20061101
  • Expected Completion Date: 0
  • Actual Completion Date: 20060201
  • Source Data: RiP Project 16783

Subject/Index Terms

Filing Info

  • Accession Number: 01464599
  • Record Type: Research project
  • Source Agency: National Cooperative Highway Research Program
  • Contract Numbers: Project 20-05, Topic
  • Files: TRB, RiP, USDOT
  • Created Date: Jan 3 2013 2:45PM