A Rational Method of Determining Life of Deficient Superpave Pavements

Superpave mixture design methodology has been implemented by most state highway agencies, including the Kansas Department of Transportation (KDOT). Sometimes KDOT engineers have to decide whether or not to accept non-conforming Superpave mixtures during construction. The life of deficient Superpave pavements incorporating nonconforming mixtures can be estimated based on Hamburg Wheel-Tracking Device (HWTD) test results and analysis. In this study, a methodology has been developed to estimate the life of Superpave pavements that are out of specifications for in-place density and/or air voids. Nine fine-graded Superpave mixes of 12.5 mm (0.5 inch) nominal maximum aggregate size (NMAS) from KDOT’s six Districts were selected for estimation of life of deficient pavements. Specimens were prepared at three different target air-void levels @ Ndesign gyrations (2%, 4% and 7%) and four simulated in-place density levels (87%, 89%, 91% and 93%) with the Superpave gyratory compactor. The average number of wheel passes to a 20 mm (0.8 inch) rut depth, creep slope, stripping slope, and stripping inflection point (SIP) in HWTD tests were used in the statistical analysis. Thus, this randomized block experiment involved a total of 108 mixtures (three air voids @ Ndesign x four in-place density levels x nine projects). HWTD tests were conducted on replicate samples until 20 mm (0.8 inch) rut depth or 20,000 wheel passes, whichever came first. Results show that in general, higher in-place density results in a higher number of wheel passes to a 20 mm (0.8 inch) rut depth in the HWTD. Superpave mixtures with very low air voids @ Ndesign level performed very poorly. Statistical analysis of HWTD test results using the analysis of variance (ANOVA) approach indicated that for most mixtures, air voids @ Ndesign and in-place density have a significant effect on the average number of wheel passes to the failure condition. For most mixtures, interaction between air voids @ Ndesign and in-place density is not significant. Good prediction of potential loss of pavement life can be made from the results of HWTD tests on the deficient mixtures. Thus, HWTD test results can be used for estimation of life of the deficient Superpave pavements.

Language

  • English

Media Info

  • Media Type: Web
  • Edition: Final Report
  • Features: Appendices; Figures; Photos; References; Tables;
  • Pagination: 138p

Subject/Index Terms

Filing Info

  • Accession Number: 01155370
  • Record Type: Publication
  • Report/Paper Numbers: K-TRAN: KSU-06-3
  • Contract Numbers: C1566
  • Files: TRIS, STATEDOT
  • Created Date: Apr 23 2010 10:10AM