MECHANISTIC EVALUATION OF SUPERPAVE LEVEL 1 MIXTURES

This research involved the mechanistic analysis of two recently built pavements using 2-in. and 3/4-in. maximum nominal size Superpave mixtures. Fatigue life equations were developed for these mixtures and a conventional mixture of the Kansas Department of Transportation (KDOT) based on the laboratory flexural fatigue tests on asphalt concrete beams. Field deflection tests were done on a 1000-ft section on each pavement with a Dynatest 8000 falling weight deflectometer. The deflection results were used to backcalculate layer moduli values. The mechanistic responses, namely, horizontal tensile strain at the bottom of the asphalt concrete layer and vertical compressive strain on top of the subgrade layer under an 18 kip Equivalent Single Axle Load (ESAL), were computed for each pavement using an elastic layer analysis software. Fatigue life, in term repetitions of 18 kip ESALs, was predicted for these pavements with the fatigue equations developed in this study. The results were then compared with the life predictions done by the equations developed by the Strategic Highway Research Program (SHRP) and the Asphalt Institute. The results show that the predicted lives obtained by Kansas State University (KSU) and SHRP equations are close for 3/4-in. Superpave mix, while those obtained by the KSU and Asphalt Institute equations are close for the conventional 2-in. mix. The 2-in. Superpave mix appeared to have a higher predicted fatigue life than the 3/4-in. mix. Overall, the Superpave mixtures appeared to have far superior predicted fatigue life than the conventional asphalt mix used by KDOT in the past. The predicted life of KDOT conventional mix under similar strains was almost one-third to one-quarter of the Superpave mixes. Based on the analysis of maximum shear stresses to evaluate the rutting potential in these Superpave pavements, it is felt that the required maximum shear stress values in the Superpave Level II mix design for tertiary creep evaluation are not realistic. Further studies are recommended in this area.

• Record URL:
  • https://ntlrepository.blob.core.windows.net/lib/18000/18700/18702/PB2002101484.pdf
• 
• Corporate Authors:

  Kansas Department of Transportation

  Materials and Research Center, 2300 Van Buren Street
  Topeka, KS  United States  66611

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590
• Authors:
  • Kaldate, R
  • Hossain, M
• Publication Date: 2001-9

Language

• English

Media Info

• Features: Figures; References; Tables;
• Pagination: 130 p.

Subject/Index Terms

• TRT Terms: Asphalt concrete; Deflection tests; Equations; Equivalent single axle loads; Falling weight deflectometers; Fatigue tests; Mathematical prediction; Mix design; Rutting; Service life; Shear stress; Strain (Mechanics); Superpave
• Identifier Terms: Asphalt Institute; Kansas State University; Strategic Highway Research Program
• Geographic Terms: Kansas
• Subject Areas: Data and Information Technology; 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: 00921522
• Record Type: Publication
• Report/Paper Numbers: FHWA-KS-01-3,, Final Report
• Contract Numbers: C948
• Files: NTL, TRIS, ATRI, USDOT, STATEDOT
• Created Date: Mar 14 2002 12:00AM