Table of Contents

• Chapter 1: Introduction
  • Background
  • Problem Statement
  • Objectives
  • Organization of Study
• Chapter 2: Literature Review
  • Introduction
  • Traditional Subgrade Testing Procedures
    • California Bearing Ratio (CBR)
    • Resistance Value (R-Value)
  • Development of the Resilient Modulus Test
  • Resilient Modulus Laboratory Testing
  • Back Calculation of Resilient Modulus
    • Non-Destructive Testing Equipment
    • Back Calculation Computer Programs
  • M_R Determination from Correlation Studies
  • Selection of a Design M_R Value
  • Utilization of Soil M_R in the AASHTO Overlay Design Procedures
    • The 1993 AASHTO Overlay Design Procedure
    • Determining the Need for an Overlay
  • Chapter Summary
• Chapter 3: Design of Experiment
  • Introduction
  • Site Selection
  • Data Collection
  • Laboratory Testing and Resilient Modulus Determination
    • Laboratory Testing for Resilient Modulus
    • Back Calculation of M_R
  • Data Base Preparation and Data Analysis
  • Evaluating the Effect of M_R Selection on Overlay Thicknesses
  • Chapter Summary
• Chapter 4: Results from Laboratory and Field Evaluations
  • Introduction
  • Site Characteristics
  • Results from Soil Property Tests
  • Laboratory Resilient Modulus Values Based on 41.4-kPa (6-Psi) Deviator Stress
  • Back Calculated Resilient Modulus Values
  • Results from R-Value Tests
  • Statistical Analysis
    • Relationship Between Resilient Modulus and R-Value
    • The Effect of Sensor Locations on M_R Measurements
    • The Effect of Sample Locations on M_R Values
    • Relationship Between Back Calculated and Laboratory M_R Values
    • Relationship Between M_R Values and Soil Properties
  • Chapter Summary
• Chapter 5: Effect of M_R Selection on Overlay Thicknesses
  • Introduction
  • Laboratory Resilient Modulus Values Based on Actual Field Stresses
    • Comparison of Laboratory M_R Values
  • Overlay Thickness Results
  • Statistical Analysis
  • Chapter Summary
• Chapter 6: Conclusions and Recommendations
  • Summary
  • Recommendations for Needed Future Research
• References
• Appendix A: Specifications for Laboratory M_R Testing*
• Appendix B: M_R Calculation Spreadsheet Example*
• Appendix C: Summary Sheet for Actuator LVDT M_R Values (Summer of 1992 & Spring of 1993)*
• Appendix D: Overlay Spreadsheet Example*

*available upon request

Selection of Subgrade Modulus for Pavement Overlay Design Procedures

by

Khaled Ksaibati, Michael L. Whelan, and James M. Burczyk
Department of Civil and Architectural Engineering
The University of Wyoming
P.O. Box 3295
Laramie, Wyoming 82071-3295

Michael J. Farrar
Wyoming Department of Transportation
P.O. Box 1708
Cheyenne, Wyoming 82002-9019

August 1994

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