Resilient Modulus of Coarse-Grained Subgrade Soils for Pavement Design

Details

• Creators:
  Hossain, M. Shabbir ; Nair, Harikrishnan
• Corporate Creators:
  Virginia Transportation Research Council (VTRC)
• Corporate Contributors:
  Virginia. Department of Transportation ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  Coarse Grained Soils Mathematical Prediction Mechanistic-empirical Pavement Design Modulus Of Resilience Pavement Design Pavement Subgrade Testing
• Publication/ Report Number:
  FHWA/VTRC 26-R35
• Resource Type:
  Tech Report
• Geographical Coverage:
  United States ; Virginia
• Edition:
  Final report: November 2022 -October 2025
• Corporate Publisher:
  Virginia Transportation Research Council (VTRC)
• Abstract:
  In 2018, the Virginia Department of Transportation (VDOT) implemented the American Association of State Highway and Transportation Officials’ (AASHTO) AASHTOWare-ME version 2.2.6 as the pavement design methodology for new, reconstruction, and lane-widening projects, including interstate, primary, and secondary routes with annual average daily traffic greater than 10,000 vehicles. The Mechanistic-Empirical Pavement Design Guide (MEPDG) and the AASHTOWare Pavement ME software provided an improved process for conducting pavement analysis and for developing pavement designs based on mechanistic-empirical principles. To facilitate the pavement design, MEPDG recommends the resilient modulus (Mr) to characterize the subgrade soils. As part of VDOT’s MEPDG implementation efforts, the Materials Division Soils Lab collected both fine-and coarse-grained soil samples from around the state on which to perform Mr tests. For fine-grained soils (A-4, A-5, A-6, and A-7), a correlation with unconfined compression strength was developed in a Virginia Transportation Research Council study that is currently being used to estimate design Mr for high-volume projects (annual average daily traffic > 10,000) as an alternative to actual Mr testing. Also, enough fine-grained soils were tested to determine statewide average Mr values to be used in the design of low-volume roadways (annual average daily traffic < 10,000). However, no statewide average Mr values or correlations are currently available for coarse-grained soils (A-1, A-2, and A-3). Although some actual measured Mr values of coarse-grained soil are available, they are significantly less than AASHTO-recommended Mr values (MEPDG default), which needs to be further investigated. During this study, six coarse-grained soil samples were tested for Mr at standard Proctor compactive effort: three A-2-4, one A-26, and two A-3. The Mr values at a confining pressure of 2 psi and a deviator stress of 6 psi were less than MEPDG-recommended default values, but they are comparable with measured values reported in the literature. Sample compaction density and moisture influenced the Mr values. The Mr value of any coarse-grained soil showed a decreasing trend with increasing degrees of saturation, a combining measure of compaction density and moisture. A few soil index properties showed good correlation with Mr values. A predictive model could not be recommended because of limited data points, that is, only six soil samples.
• Format:
  PDF
• Funding:
  122364
• Collection(s):
  Federal Highway Administration
• Main Document Checksum:
  urn:sha-512:cd831609e138f112b483241a145eaa6593103d51c13a090196cccb171b46c004aa0b45a2d4e2e7654f05b4b6b0c4ed388cdea8e84042b6c4c852a00ec2aaf0d8
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/89731/dot_89731_DS1.pdf
• File Type:
  [PDF - 3.01 MB ]