Effect on Dynamic Modulus Measurement Protocol on Predicted Pavement Performance

Two different standard protocols are available to meet the needs of both research and practicing pavement engineers respectively, and differ slightly in several key details. AASHTO TP 62 and AASHTO TP 79 used in combination with AASHTO PP 61, exist for the measurement of the dynamic modulus of asphalt concrete. The TP 79/PP 61 protocol does not include measurements at temperatures below 5C, whereas the TP 62 protocol requires measurement of the dynamic modulus at -10C. Since the dynamic modulus has become the primary material property input for performing pavement analysis with asphalt concrete, there is concern about potential influences that the choice of test protocol may have on performance predictions, pavement design, and ultimately the actual performance of a pavement structure. This paper presents the results from an analytical study to compare the dynamic modulus values generated by these two protocols. The purpose of this analysis is three-fold: 1) to examine the experimental and analytical procedure suggested in AASHTO TP 79/PP 61 for accuracy and bias; 2) to examine the potential effects of any errors as they relate to routine pavement analysis; and 3) to examine the potential effects of these errors on advanced material model predictions. The differences in the two protocols are first discussed and then the moduli predicted or measured by the two protocols at different temperatures are compared. A database of 17 different mixtures and 48 different individual specimens is used for this purpose. Next, the effects of these differences are assessed in terms of rutting, fatigue cracking, and roughness performance predictions using the NCHRP 1- 37A Mechanistic-Empirical Pavement Design Guide. Following this analysis, the viscoelastic continuum damage model is characterized and then utilized with data from both protocols to make material level thermal cracking predictions and structural level fatigue cracking predictions. It is found that the TP 79/PP 61 protocol does not predict the modulus values at the extreme cold, and to a lesser extent the extreme warm temperatures very well. However, for the performance predictions it is found that in all cases the effect of the LVE characterization protocol is generally small, even for the case of thermal cracking where cold temperatures not characterized in the AASHTO TP 79/PP 61 protocol are encountered. Due to these results it is concluded that analyzing and testing with the reduced protocol suggested in AASHTO TP 79/PP 61 would be acceptable for agencies willing to accept potential differences of approximately 5-10% in predicted distress and the effects that are associated with those potential differences, on the reliability of calibrated mechanistic models.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/02702932
• Authors:
  • Underwood, Shane
  • Ashouri, Morteza
  • Kim, Y Richard
• Discussers:
  • Hajj, Elie
  • Underwood, B Shane
• Conference:
  • Asphalt Paving Technology 2011
  • Location: Tampa FL
  • Date: 2011-3-27 to 2011-3-30
• Publication Date: 2011

Language

• English

Media Info

• Media Type: Print
• Features: CD-ROM; Figures; References; Tables;
• Pagination: pp 65-100
• Serial:
  • Journal of the Association of Asphalt Paving Technologists
  • Volume: 80
  • 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 pavements; Dynamic modulus of elasticity; Measurement; Pavement performance
• Identifier Terms: Mechanistic-Empirical Pavement Design Guide
• Uncontrolled Terms: Viscoelastic continuum damage model
• Subject Areas: Design; Highways; Materials; I22: Design of Pavements, Railways and Guideways; I31: Bituminous Binders and Materials;

Filing Info

• Accession Number: 01367540
• Record Type: Publication
• Files: TRIS
• Created Date: Apr 10 2012 3:17PM