Characteristics of the Loading Pulse for the Flow Number Performance Test

The flow number (FN) test for asphalt mixtures was one of the final three tests selected, along with the repetitive simple shear test at constant height, and the flow time under creep test, for further evaluation from the twenty-four test/material properties initially examined under the NCHRP 9-19 project. Currently, a repeated haversine axial compressive load pulse of 0.1 second and a rest period of 0.9 second is commonly used as part of the triaxial testing conditions. Nonetheless, there is no standard procedure that specifies the magnitude of the loading pulse duration that represents the actual field conditions. The objective of this research is to develop guidelines for the selection of the equivalent deviator pulse characteristics that best simulate the conditions encountered in the pavement under traffic loads. Extensive mechanistic analyses of three different asphalt pavement structures subjected to moving traffic loads at various speeds and under braking and non-braking conditions were conducted using the 3D-Move model. The pulse time was determined by best-fitting a haversine wave shape for the equivalent triaxial deviator stress pulse that was calculated from the octahedral shear stress (τoct) at 2 in. below pavement surface under a moving 18-wheel truck at different speeds and temperatures. Prediction equations for estimating the anticipated deviator pulse duration as a function of pavement temperature, and vehicle speed have been developed. In addition, ranges for the amplitude of the triaxial deviator and confinement stresses as a function of pavement stiffness properties and traffic speeds are also provided.

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  • Authors:
    • Hajj, Elie Y
    • Ulloa Calderon, Alvaro Esteban
    • Siddharthan, Raj V
    • Sebaaly, Peter E
  • Conference:
  • Publication Date: 2010

Language

  • English

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  • Accession Number: 01328001
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jan 20 2011 11:22AM