The fatigue considerations in design were identified by doing a detailed study of a road between Regina and Lumsden in the Province of Saskatchewan. The roadway was opened to traffic in 1962 and fatigue failures appeared in 1962 and fatigue failures appeared in 1968. Detailed truck traffic information was available from a weigh scale located midway along the case study. The development of failure during 1968 and 1969 was well documented. Samples were obtained from the roadway for resilient modulus tests on the subgrade, subbase and base. Stiffness and fatigue tests were carried out on the asphalt concrete samples at 32 F (0 C) and 70 F (21.1 C). Benkelman Beam deflection tests were performed at twelve sites on the case study at the same location as the sampling for materials characterization tests. Using laboratory measured properties and the CHEV 5L program deflections were calculated and then compared to measured deflections. The results were very similar indicating the laboratorv results are a good indication of in situ values and the analytical procedure closely duplicates field deflection. A method of predicting the pavement temperature environment from meteorological data and asphalt concrete properties was checked by using temperature measurements from the Ste. Anne test road. The results were found to be sufficiently assurate for fatigue simulation. Truck loading information, materials characterization and environmental information were used together with a fatigue program to simulate fatigue on the test road. Failure of the road occurred in 1968 and the simulation predicted failure at about the same time. The simulation of failure indicated the importance of considering fatigue parameters at various temperatures, the importance of using the mode factor, the sensitivity of the program to seasonal changes in subgrade modulus and the need for consideration of truck traffic in detail. /AUTHOR/

  • Authors:
    • Bergan, A T
    • Monismith, C L
  • Publication Date: 1972

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  • Accession Number: 00096460
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 13 1975 12:00AM