Performance of Drained and Undrained Rigid Pavements in Long-Term Pavement Performance SPS-2 Experiment

Drainage is the experimental factor about which conclusions from the SPS-2 experiments are most difficult to draw. This is because two experimental factors, base type and subdrainage, are confounded in the experiment. This paper describes the findings from NCHRP Project 1-34D, in which data from the LTPP SPS-2 (rigid) pavement design experiment were used to assess whether pavements with subsurface drainage systems (permeable base, collectors, and outlets) performed differently from pavements without subsurface drainage systems. The data analyzed included IRI, faulting, cracking, and deflection data from the LTPP database, as well as drainage system flow time measurements obtained from field testing. Whatever effect the base type/drainage factor has had on the SPS-2 pavement sections’ latest observed IRI values and rates of change in IRI over time is concluded to be due predominantly to differences in base stiffness. The potential effect of drainage is not necessarily ruled out, but no particular evidence was detected for the role of drainage, independent of the role of base stiffness, in the development of roughness in the SPS-2 pavements. Whatever effect the base type/drainage factor has had on the development of faulting in pavements in the SPS-2 experiment has been due to the stiffness of these bases compared to the lesser stiffness of the undrained dense-graded aggregate base. This conclusion is reinforced by the observation that the undowelled pavements with aggregate base developed more than twice as much faulting as undowelled pavements with drained or undrained stabilized bases, even those at the same sites. The stiffest base type in the SPS-2 experiment, lean concrete base, may have been good for performance in terms of roughness and faulting, but it had a pronounced detrimental effect on cracking performance, particularly in the thinner concrete slabs in the experiment. Sections with the weakest base type, undrained aggregate base, also had more cracking than sections with drained permeable asphalt-treated base. On the other hand, sections with undrained HMAC and CAM bases had even less cracking than sections with drained PATB. The above findings suggest that the differences in cracking observed to date are due not to drainage differences but differences in base stiffness.


  • English

Media Info

  • Media Type: CD-ROM
  • Features: References; Tables;
  • Pagination: 21p
  • Monograph Title: TRB 86th Annual Meeting Compendium of Papers CD-ROM

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Filing Info

  • Accession Number: 01043595
  • Record Type: Publication
  • Report/Paper Numbers: 07-3495
  • Files: TRIS, TRB
  • Created Date: Feb 8 2007 8:10PM