The patterns of pavement roughness caused by expansive clay appear to be predictable from the mineralogical and pedologic properties of the clay deposit. Surveying measurements made in two gilgai fields with similar mineralogy reveal a high degree of statistical similarity in wavelengths and amplitudes of the surface ways. Field measurements of water content, suction, density, and horizontal and vertical displacements of the soil with depth throughout one weather cycle beneath the mounds and the depressions have revealed the mechanism of differential heaving of these expansive clay deposits. Pavement roughness was measured on pavements adjacent to the gilgai fields and on other pavement sections by the GM profilometer. Digital magnetic tapes of the profilometer data are analyzed by a series of digital filters especially designed for expansive clay wavelengths. Statistical data on the wavelengths and amplitudes of these typical expansive clay roughness patterns are determined and compared with those measured in the gilgai fields where these patterns have not been tampered with. The riding characteristics of these pavements as measured by the Mays meter are analyzed with a computerized model of a vehicle that is programmed to accept GM profilometer data. Dynamic load factors for the actual pavements are determined. Equations are presented that give Mays meter readings and dynamic load factors for any combination of expansive clay wavelengths and amplitudes. The effect of the dynamic load on reducing the service life of the pavement is discussed, and methods of predicting level-up and overlay quantities from the characteristics of expansive clay roughness are given.

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 9-23
  • Monograph Title: Swelling soils
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00138136
  • Record Type: Publication
  • ISBN: 0309024811
  • Files: TRIS, TRB
  • Created Date: Sep 4 1976 12:00AM