Injection of Structural Polymer Foam to Control Highway Frost Heave

An innovative technique is presented to control frost heave that is rapid to perform, is easy to control and is safer than other procedures during remediation. A two part structural polymer is injected below the highway subbase to create a permanent layer of expanded structural foam that acts as an insulation layer to limit heat loss from below. Because the heat loss is less, the temperature of the subgrade remains higher which makes it less likely to freeze and heave. The results of a successful two-year study are presented. Frost heave is caused by water freezing into ice lenses in the pore space of silty soils. As the water freezes, it accumulates into ice lenses that can lift the frozen base course aggregates above it. The heave is highly variable because small variations in soil properties can make the surface of a flexible pavement irregular and dangerous on which to drive. This paper describes the application process of an expanding structural polymer and its success in mitigating the problem. Heaves in a 100 foot (30 m) long section of flexible pavement were reduced from 3 inches (75 mm) to less than one-half inch (12.5 mm) over most of the road to a level undetectable to the motorist. In-situ temperatures were measured using thermistors above and below the polymer layer and the effect of the freezing front on the measured surface heave are compared in both treated and non-treated areas.