Estimation of Lives of Deficient Superpave Pavements

• Published in: Transportation research record 2008-01, Vol.2081 (1), p.83-91
• Main Authors: Manandhar, Chandra, Hossain, Mustaque, Nelson, Paul, Hobson, Cliff
• Format: Article
• Language: English
• ISSN: 0361-1981; 2169-4052
• DOI: 10.3141/2081-09

Nonconforming Superpave® mixtures are often encountered during construction of asphalt-surfaced pavements in Kansas. There is no rational method available to find the potential reduction in life of these pavements. Results are presented for a study in which a methodology has been developed to estimate the lives of Superpave pavements that are out of specifications for simulated in-place density and air voids. Five fine-graded, 12.5-mm nominal maximum aggregate size Superpave mixtures, sampled from five different projects, were used in this study. Replicate test specimens were prepared at three different target air void levels at Ndesign gyrations and four air void levels of the molded gyratory specimens. Hamburg wheel tests were conducted on replicate samples up to a rut depth of 20 mm or 20,000 wheel passes, whichever came first. The results were also analyzed to compute three parameters: creep slope, stripping slope, and stripping inflection point. Analysis of the results shows that, in general, higher simulated in-place density up to a certain limit results in a higher number of wheel passes up to a 20-mm rut depth in the Hamburg wheel tester. Superpave mixtures with very low air voids at Ndesign level performed very poorly in the Hamburg wheel tester. Statistical analysis of the Hamburg wheel tester results using the analysis of variance approach indicated that, for most mixtures, air voids at Ndesign and simulated in-place density have a significant effect on the average number of wheel passes to the failure condition. Good prediction of potential loss of pavement life can be made from the results of Hamburg wheel tests on the deficient mixtures. Thus Hamburg wheel test results can be used for estimation of life of defective Superpave pavements.