Characterization of time-dependent changes in strength and stiffness of Florida base materials : final report, October 2008.

Details

• Creators:
  Toros, Ulas ; Hiltunen, Dennis R. ; Campos, Luis A. ; Roque, Reynaldo ; McVay, Micheal C. ; Birgisson, Bjorn
• Corporate Creators:
  University of Florida. Dept. of Civil and Coastal Engineering
• Corporate Contributors:
  Florida. Department of Transportation. Research Center
• Subject/TRT Terms:
  • Subgrade materials
  • Road materials
  • Roads--Florida--Subgrades
  • Road materials--Florida
• Resource Type:
  Research Paper
• Geographical Coverage:
  Florida
• Edition:
  Final report.
• Corporate Publisher:
  University of Florida. Department of Civil and Coastal Engineering
• Abstract:
  Resilient modulus and Young’s modulus are parameters increasingly used to fundamentally characterize the behavior ; of pavement materials both in the laboratory and in the field. This study documents the small-strain Young’s modulus ; and larger-strain resilient modulus response of unbound aggregate base coarse materials to various environmental ; conditions. The small-strain Young’s modulus experiments were conducted on laboratory compacted materials and ; field core materials by the authors. The State Material Office conducted the resilient modulus experiments on ; laboratory compacted materials. The results of both tests are presented in this study. It is shown that the small-strain ; Young’s modulus is not constant, even when held at constant moisture, and that significant changes in modulus will ; occur with drying and wetting of the material. The response to drying and wetting cycles appears to be repeatable, and ; suggests that the underlying mechanism that controls the response is reversible. It is also shown that the larger-strain ; resilient modulus demonstrated similar trends with small-strain Young’s modulus, but the rate of change and ; magnitude of the effect are different between materials. The material response to drying and wetting cycles appears to ; be reasonably repeatable. Comparison of both experiments revealed that the change in Young’s modulus with drying is ; much more dramatic than the resilient modulus, indicating that the drying effect is significantly reduced with higher ; strain. Lastly, the evidence suggests that these changes can be explained by the science of unsaturated soil mechanics: ; changes in moisture or moisture distribution results in changes in internal pore pressure, which affect the effective ; confining pressure constraining the material. The influence of this phenomenon is observed but is not as dramatic at ; higher strain. Based upon these results it appears that a pavement design process based on resilient modulus for the ; base material should account for changes in moisture content anticipated in the base during the life of the pavement ; structure. The authors are aware that a procedure for the effects of moisture changes and other seasonal effects on the ; resilient modulus of the base material has been implemented in the new Mechanistic-Empirical (M-E) Pavement ; Design Guide. It is thus recommended that this procedure be utilized in conjunction with the findings reported herein ; to design pavements in Florida.
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• Format:
  PDF
• Funding:
  BD545-44
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/17050/dot_17050_DS1.pdf
• File Type:
  [PDF - 17.85 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:a1d383c08a24c55cd208f7b27bddc9520615bd4dfbca901f94b543f09bfa00ca