Interpretation of Shakedown Limit from Multistage Permanent Deformation Tests

A multistage permanent deformation (PD) test of geomaterials is more economical than the single-stage variety. Only one sample must be tested for the former, whereas several tests on multiple samples are required for the latter. Yet no standards exist for this test in the United States, nor is there a generally accepted procedure for determining the deviator stress to separate acceptable from unacceptable behavior in a multistage PD test. On the basis of both single- and multistage PD tests on a virgin aggregate and two recycled materials and their blends, this paper proposes a procedure to identify the material shakedown limit in a multistage PD test. Resilient modulus increases under low deviator stresses and decreases when deviator stresses are high or near failure. When applied to the materials tested, the multistage PD test predicted correctly the behavior of single-stage test samples 78% of the time. To validate the procedure, additional verification and a standard test load sequence are needed. The sequence proposed in NCHRP Report 598 presents a good starting point. The deviator stress intervals should be small enough to allow all three behavioral ranges to be captured and the load frequency low enough for the sample to drain and recover from viscous effects. One more recommendation is to use a confining stress representative of the field pavement section to be studied.


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  • Accession Number: 01155760
  • Record Type: Publication
  • ISBN: 9780309160360
  • Report/Paper Numbers: 10-1464
  • Files: TRIS, TRB, ATRI
  • Created Date: Jan 25 2010 10:39AM