INSULATION OF SUBGRADE-SECOND YEAR SUMMARY

THE EFFECTIVENESS WAS EVALUATED OF AN INSULATING MATERIAL INSTALLED TO PREVENT OR REDUCE FREEZING OF THE SUBGRADE SOILS AND CONSEQUENTLY TO REDUCE OR ELIMINATE DIFFERENTIAL FROST HEAVES IN PAVEMENTS. THE INSULATION USED WAS STYROFOAM WHICH WAS PLACED IN TWO LANES OF A RELOCATED MAJOR HIGHWAY ABOUT TEN MILES SOUTH OF BANGOR, MAINE. THE ADJACENT TWO LANES, WHICH ARE UNINSULATED, SERVE AS A NORMAL ROADWAY FOR COMPARISON WITH THE INSULATED SECTIONS. BY MEANS OF MORE THAN 250 THERMOCOUPLES, THE SUBSURFACE TEMPERATURES WERE MONITORED THROUGHOUT TWO FREEZING SEASONS. THE SOILS BENEATH THE CENTER OF THE INSULATION WERE PREVENTED FROM COOLING TO 32 F. WATER CONTENT MEASUREMENTS OF THE SOILS BOTH ABOVE AND BELOW THE INSULATION WERE OBTAINED BY MEANS OF NUCLEAR DEPTH PROBES. THE RESULTS SUGGEST THAT THE STYROFOAM FORMS AN EFFECTIVE BARRIER TO THE MIGRATION OF MOISTURE. THE PRIMARY BENEFIT OF THE STYROFOAM IS THE UNFROZEN SUBGRADE WHICH EXPERIENCED LESS HEAVE DURING THE BREAK-UP PERIOD THAN THE UNINSULATED SECTION. THE HEAVE MEASUREMENTS WERE OBTAINED FROM SUCCESSIVE LEVEL SURVEYS WHICH WERE COMPARED WITH A REFERENCE ELEVATION OBTAINED PRIOR TO EACH FREEZING SEASON. BENKELMAN BEAM DEFLECTION MEASUREMENTS OBTAINED AT INTERVALS THROUGHOUT EACH FREEZING SEASON INDICATE LESS DEFLECTION ON THE INSULATED SECTIONS DURING THE BREAK-UP PERIOD. THE UNINSULATED SECTION DEVELOPED NUMEROUS PAVEMENT CRACKS, BUT BECAUSE OF THE UNFROZEN SUBGRADE, THE PAVEMENT IN THE INSULATED SECTIONS EXHIBITS NO EVIDENCE OF CRACKING. A DISC PRESSURE CELL SYSTEM WAS INSTALLED TO MEASURE SOIL PRESSURE ABOVE AND BELOW THE STYROFOAM. UNFORTUNATELY THIS MEASURING SYSTEM PROVED UNSATISFACTORY.

  • Supplemental Notes:
    • No 66-8, InTERIM REPORT NO 4-HPR-PR-1(25), 56 FIG, 3 TAB,
  • Corporate Authors:

    Maine State Highway Commission

    Soils and Planning Divisions
    Augusta, ME  USA 

    Department of Commerce

    1401 Constitution Avenue, NW
    Washington, DC  USA  20230

    Bureau of Public Roads /US

    400 7th Street, SW
    Washington, DC  USA  20590
  • Authors:
    • Dunphy, W J
    • Bigelow, N
  • Publication Date: 1966-9

Subject/Index Terms

Filing Info

  • Accession Number: 00237426
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 13 1994 12:00AM