Citation

Esch DC. Transp. Res. Rec. 1995; 1481: 56-62.

Copyright

(Copyright © 1995, Transportation Research Board, National Research Council, National Academy of Sciences USA, Publisher SAGE Publishing)

DOI

unavailable

PMID

unavailable

Abstract

The use of expanded plastic foam insulations in Alaska to reduce freezing and thawing of soils beneath road and airfield embankments began in 1968 with the installation of polystyrene and polyurethane foam products for frost-heave control. This was followed in 1969 by the first insulated roadway section over permafrost in North America, at Chitina, and by the first insulated airfield runway, at Kotzebue. Since then, many roadway sections, totaling more than 45 lane-km, have been insulated by the Alaska Department of Transportation, as have four additional airports. Materials used have been primarily extruded-expanded polystyrene foam, with one installation of foamed-in-place polyurethane and three of molded polystyrene beadboard. Evaluations of the long-term performance of these installations have included periodic sampling and testing of the insulations. On the basis of these observations, foamed-in-place polyurethane insulation was rejected for subgrade insulation uses, whereas extruded polystyrene was preferred based on its superior performance and longevity. Molded polystyrene beadboard has given acceptable performance, but it must be installed at a thickness 30 to 50% greater than that of the extruded polystyrenes to provide comparable thermal performance. Comparisons are given between insulated and noninsulated embankment behavior on permafrost and between measured and calculated late summer thaw depths. The modified Berggren calculation method, which provided reasonable 1-year thaw estimates, was used for the comparisons.

Language: en

Keywords

Embankments; Airport runways; Roads and streets; Foamed plastics; Freezing; Frost protection; Polystyrenes; Polyurethanes; Thawing; Thermal insulating materials; Thermal insulation