Frost Heave Mitigation Using Polymer Injection and Frost Depth Prediction.

An innovative approach to mitigate frost heave problems in flexible pavements is to inject a two-part expanding polymer at the bottom of the subbase. As the polymer expands, it creates an insulation layer that minimizes heat loss from the profile and prevents the frost front from entering the subgrade. The technique has been used in a section of Wyoming highway WY-70 6.4 km west of Encampment, WY. A two-year study measured road surface deviations and temperatures in the soil profile. The frost heave over a 30-m long section was reduced from greater than 75 mm to less than 17 mm. The maximum frost penetration depth was determined in five holes over two seasons using the measured temperature data in the road/soil profile including boreholes with 0, 25, and 75 mm of expanded polymer. These data were compared to depths predicted by the Modified Berggren Equation. The standard deviation for the ten estimates was 52 mm over a range of freezing depths from 500 mm to 1100 mm. The maximum error of prediction was 82 mm, while five of the ten errors were less than 20 mm. It was determined that the polymer behaved like volumetric latent heat. The technique appears to successfully predict the frost depths well enough to use as a predictor in design. However, these results are based solely on an analysis using Uretek 486 STAR #3 structural polymer at this site and time period. [ABSTRACT FROM AUTHOR]