EVALUATION OF TEST METHODS FOR STIFFNESS PROPERTIES OF HOT MIX ASPHALT (HMA)

The current 1993 AASHTO "Design Guide for Design of Pavement Structures" uses resilient modulus to assign an "a" coefficient to hot mix asphalt (HMA) to determine the required thickness of the HMA layer for a given traffic loading and subgrade support condition. There are several methods to determine the modulus of a mix for use in determining the "a" coefficient. Modulus results are a function of the test method and curing conditions. Therefore, the test method and curing conditions would have an effect on the "a" coefficient used in thickness design and, hence, the thickness of the pavement layers. A need was voiced by the Kansas Department of Transportation (KDOT) to evaluate the available test methods for determination of the stiffness properties of HMA. The laboratory stiffness properties of a coarse and fine, 19 mm HMA mixture were evaluated. One indirect method used total external horizontal deflections and the other both inner horizontal and inner vertical deflections. In addition, two experimental procedures were evaluated; they were a direct measurement procedure using a GeoGauge (Trademark) and a pulse-velocity procedure described in ASTM C 1383 and ASTM C 597. The study was terminated by KDOT prior to completion of the initial test plan with the major reason being the emphasis being placed on complex dynamic modulus by the forthcoming 2002 Design Guide. Conclusions based on the limited test data indicated that the short-term oven aging protocol of AASHTO TP4 resulted in significantly higher modulus values than previously reported. The direct measurement procedure gave similar results to the pulse-velocity procedures of ASTM C 1383 and C 597.

Language

  • English

Media Info

  • Features: Figures; Tables;
  • Pagination: 22 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00987635
  • Record Type: Publication
  • Report/Paper Numbers: K-TRAN: KU-01-3,, Final Report
  • Contract Numbers: C1239
  • Files: NTL, TRIS, STATEDOT
  • Created Date: Mar 4 2005 12:00AM