EXPERIMENTAL INSULATION OF A SUBGRADE IN HAMPDEN, MAINE

An experimental section was constructed in which insulation was in the form of two foot by eight foot by 1.5 inch boards placed on the subgrade and held in place by wooden pegs. A 6-inch layer of sand was spread over the insulation with a bulldozer and compacted with a self-propelled, multi-plate vibratory compactor. Layers of base material was placed above the sand layer. The instrumentation used to record 48 temperatures automatically at preset intervals of time is briefly outlined. The pressure measuring sensors were flat transducers of one square centimeter area. The deflection measuring system was devised to detect deflections of the upper surface of the insulation under load. Deflection measurements of the roadway surface was conducted using the Benkelman beam. The moisture content was measured by a nuclear soil moisture probe. Periodic elevation surveys were conducted during the late fall, winter and spring. The measurement results are discussed. The subgrade temperatures are warmer in the winter and cooler in the summer immediately beneath the insulation than at the same location in a comparable uninsulated position. There is, however, no evidence that the insulation has altered the temperature regime deeper than 3 or 4 feet beneath the center of the roadway and seen less beneath the edges of the insulation. The great amount of information gathered from the temperature data is reviewed. Pavement evaluation, moisture analysis, pressure analysis, deflection analysis, surface movement and insulation analysis are other aspects covered. The data leads to the conclusion that Polystyrene foam maintains its physical integrity and absorbs only a minimal amount of moisture even after long burial in a roadway. The roadway surfaces above insulated sections maintain a smoother, more comfortable riding surface. These surfaces also seem to be less distorted and cracked than surfaces over adjacent uninsulated sections. Although freezing moisture in the base material causes some small amount of heaving, the insulated areas heave much more than the uninsulated areas.

  • Supplemental Notes:
    • This paper was presented during the Symposium on Frost Action on Roads held in Oslo, Norway 1-3 October, 1973.
  • Corporate Authors:

    Organisation for Economic Co-operation and Development (OECD)

    2, rue André Pascal
    Paris,   France  75775 Paris Cedex 16
  • Authors:
    • Durphy Jr, W J
  • Conference:
  • Publication Date: 1973

Media Info

  • Features: Figures;
  • Pagination: p. 329-328

Subject/Index Terms

Filing Info

  • Accession Number: 00260462
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: Conf Paper
  • Files: ITRD, TRIS
  • Created Date: Oct 11 1975 12:00AM