Performance of city pavement structures containing foamed plastic insulation

This paper presents one winter's results of two 100-ft city pavement sections insulated with a 2-in. thickness of extruded polystyrene plastic foam in Sudbury, Ontario, Canada. The experimental results consisted of temperature measurements, frost-depth measurements with methylene blue gages, elevation measurements for frost heave and Benkelman beam deflections following the thawing period. The insulation reduced frost penetration by 35 in. during a 2600 degree-day winter. Thermoconductivity measurements showed that no deterioration occurred in the insulating properties of the insulation. Frost penetration in the control area was approximately 65 in., which compared favorably with the depth predicted by the U.S. Army Corps of Engineers from measurements in granular base course beneath snow-cleared airport runways.