THE INFLUENCE OF CLIMATIC FACTORS ON THE STRUCTURAL DESIGN OF FLEXIBLE PAVEMENTS

Current design standards for flexible pavements in Britain are based on the results of full-scale road experiments extending over 20 years. The influence of seasonal and climatic factors is taken into account by such a protracted period of abservation. In extending the use of the standards to other climatic environments or in applying methods of structural analysis to them, the influence of climate on the performance of the various elements of the pavement needs to be appreciated. The first part of the paper considers the influence of climate on the strength of soil foundations. Recent research in the field of soil mechanics is used to isolate three broad subgrade moisture conditions based on rainfall, evapo-transpiration and the position of the water-table. The role of vapour transfer in influencing subgrade strength is also discussed. High temperatures reduce the modulus of the bituminous elements of the pavement and again the effects of this on the stress regime are discussed. Augmented vertical stresses in the subgrade, as well as a loss of stability in the bituminous material may lead to increased deformation under traffic during hot weather. However, the ability of the materials to accept higher levels of strain reduces the risk of cracking under these conditions. Sub-zero temperatures normally lead to a much increased modulus both in bituminous materials and subgrades. The transfer of water into the subgrade during the downward progress of the zero isotherm will however reduce the elastic modulus of the subgrade drastically immediately after the thaw. The implications of this on pavement stresses must be considered. Published data have been used to estimate for four soil types and for two granular sub-base and base materials the probable effect on strength of a wide range of climatic conditions. Strength of a wide range of climatic conditions. Strengths are expressed in terms of CBR or elastic madulus. Used in conjunction with structural design procedures these values will give some indication of the influence of climate on pavement thickness requirments. /Author/

  • Supplemental Notes:
    • Presented at the Third International Conference on the Structural Design of Asphalt Pavements, Grosvenor House, Park Lane, London, England, Sept. 11-15, 1972.
  • Corporate Authors:

    International Conf Struct Design Asph Pvmts (3rd)

    University of Michigan, Department of Civil Engineering
    Ann Arbor, MI  United States  48104

    International Conf Struct Design Asph Pvmts (3rd)

    University of Michigan, Department of Divil Engineering
    Ann Arbor, MI  United States  48104

    Interrational Conf Struct Design Asph Pvmts (3rd)

    University of Michigan, Department of Civil Engineering
    Ann Arbor, MI  United States  48104
  • Authors:
    • Croney, D
    • Bulman, J N
  • Conference:
  • Publication Date: 1972-9

Media Info

  • Features: References; Tables;
  • Pagination: p. 67-71
  • Serial:
    • Volume: 1

Subject/Index Terms

Filing Info

  • Accession Number: 00261978
  • Record Type: Publication
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Oct 22 1974 12:00AM