An Examination of Strain Levels Used in the Dynamic Modulus Testing (With Discussion)

Recent published studies clearly emphasize the importance of dynamic modulus (|E*|) testing of hot-mix asphalt concrete (HMA). The dynamic modulus is one of the fundamental inputs in the mechanistic-empirical (M-E) Design Guide developed through National Cooperative Highway Research Program (NCHRP) Project 1-37A. The current AASHTO TP62-03 specifies that the dynamic stress be adjusted to obtain: (1) axial recoverable strains between 50 and 150 microstrain; and (2) cumulative permanent strain of less than 1,500 microstrain at the end of the tests at each temperature level. The requirement is to maintain the test specimen behavior in its linear viscoelastic range during the |E*| testing regime. However, it is suspected that axial dynamic strains between 100 and 150 microstrain may produce cumulative permanent strain levels which affect the linear viscoelastic response of the material, which in turn affects the |E*| results that influence predicted pavement performance. In order to investigate the effect of the dynamic strains, a study of four |E*| tests was conducted. Two |E*| tests were performed on a set of three replicate specimens using axial dynamic strains between 50 and 100 microstrain. Another two |E*| tests were performed on a second set of three replicate specimens using axial dynamic strains between 100 and 150 microstrain. The two sets of test specimens were fabricated using the same HMA mixture. The results showed that the |E*| determined using the two dynamic strain levels were significantly different at high temperatures (38 and 54C). Based on the study results, it is recommended that axial dynamic strain levels used in E* testing be re-evaluated and possibly reduced to account for possible viscoelastic response effects.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/02702932
• Authors:
  • Tran, Nam H
  • Hall, Kevin D
• Discussers:
  • Pellinen, Terhi
  • Nady, Robert
  • Mohseni, Ala
  • Christensen, Donald
  • Huang, Baoshan
  • Stephens, Jack
• Conference:
  • 2006 Journal of the Association of Asphalt Paving Technologists: From the Proceedings of the Technical Sessions
  • Location: Savannah Georgia, United States
  • Date: 2006-3-27 to 2006-3-29
• Publication Date: 2006

Language

• English

Media Info

• Media Type: Print
• Features: CD-ROM; Figures; References; Tables;
• Pagination: pp 321-343
• Serial:
  • Journal of the Association of Asphalt Paving Technologists
  • Volume: 75
  • Publisher: Association of Asphalt Paving Technologists (AAPT)
  • ISSN: 0270-2932
  • Serial URL: https://www.asphalttechnology.org/site_page.cfm?pk_association_webpage_menu=9169&pk_association_webpage=19109

Subject/Index Terms

• TRT Terms: Asphalt concrete; Dynamic modulus of elasticity; Hot mix asphalt; Pavement performance; Strain (Mechanics); Temperature; Testing; Viscoelasticity
• Identifier Terms: Mechanistic-Empirical Pavement Design Guide
• Uncontrolled Terms: Dynamic strain response
• Subject Areas: Design; Highways; Materials; Pavements; I22: Design of Pavements, Railways and Guideways; I23: Properties of Road Surfaces; I31: Bituminous Binders and Materials;

Filing Info

• Accession Number: 01041383
• Record Type: Publication
• Files: TRIS
• Created Date: Jan 30 2007 1:29PM