SELECTION OF SUBGRADE MODULUS FOR PAVEMENT OVERLAY DESIGN PROCEDURES

This study was conducted to better understand how selecting a subgrade resilient modulus (M sub R) value influences the thickness of an asphalt overlay pavement. The objectives of this study were to: 1) investigate the importance of several fundamental soil properties (water content, plasticity index, liquid limit, group index) on selecting a design M sub R value for cohesive soils; 2) define the actual relationship (correction factor) between backcalculated and laboratory-based M sub R values for typical cohesive subgrade soils in Wyoming; 3) compare actual subgrade field deviator stresses to the deviator stress assumed in determining a design M sub R value from laboratory testing; and 4) determine the effect of selecting an M sub R value on the design overlay thicknesses for typical pavement sections in Wyoming. The data analysis resulted in several important conclusions about factors that influence the determination of the M sub R value and how this value affects the final overlay thickness design for a given pavement section. Chapter 1 of this report provides an introduction. Chapter 2 reviews the traditional methods used to characterize subgrade soils, methods to determine M sub R for subgrade soils, and the AASHTO overlay design procedure. Chapter 3 describes the data collection process and overall evaluation strategies followed in this research. Chapter 4 discusses the laboratory testing, backcalculation testing, and several important results on the factors that influence the selection of a design subgrade M sub R value. Chapter 5 discusses the impacts of selecting a particular method for determining a design M sub R value on the resulting overlay thickness. Chapter 6 summarizes the study, presents the conclusions, and makes recommendations for needed future research.

• Record URL:
  https://www.ugpti.org/resources/reports/details.php?id=320
• Supplemental Notes:
  • This study was funded through the U.S. Department of Transportation's University Transportation Centers Program.
• Corporate Authors:

  University of Wyoming, Laramie

  Wyoming Survey and Analysis Center, 710 Garfield
  Laramie, WY  United States  82070

  Wyoming Department of Transportation

  5300 Bishop Boulevard
  Cheyenne, WY  United States  82009-3340
• Authors:
  • Ksaibati, K
  • Whelan, M L
  • Burczyk, J M
  • Farrar, M J
• Publication Date: 1994-8

Language

• English

Media Info

• Media Type: Digital/other
• Features: Appendices; Figures; Photos; References; Tables;
• Pagination: 172 p.

Subject/Index Terms

• TRT Terms: Backcalculation; Bituminous overlays; Coefficient of subgrade reaction; Cohesive soils; Deviatoric stress; Future; Laboratory tests; Modulus of resilience; Overlays (Pavements); Research; Thickness
• Uncontrolled Terms: Future research
• Old TRIS Terms: Deviator stress; Thickness design
• Subject Areas: Data and Information Technology; Design; Geotechnology; Highways; Pavements; Research; I22: Design of Pavements, Railways and Guideways; I42: Soil Mechanics;

Filing Info

• Accession Number: 00674272
• Record Type: Publication
• Report/Paper Numbers: MPC Report No. 94-34
• Files: TRIS, STATEDOT
• Created Date: Feb 16 1995 12:00AM