Highway agencies have been experiencing difficulty with roadways settling due to the presence of peat deposits. Traditional remedial methods (such as overlays and cementitious grout) provide short-term solutions by addressing the symptoms, but not the underlying problem. Further, these treatments actually exacerbate the problem by placing additional weight on an already overstressed soil structure. Treatment by full depth removal can be time consuming and extremely costly. An expedient, long-term solution that can reduce the frequency of remedial maintenance is needed. One such solution could include insitu stabilization with a strong, lightweight material. The broad objective of this study was to evaluate insitu injection of polyurethane foam as a viable method for improving soil stiffness beneath a simulated pavement structure. The specific objective was to assess the URETEK Deep InjectionTM (UDI) process for stabilizing buried peat deposits in highway applications. A simulated rigid pavement system was constructed over a sand subgrade incorporating a 2-ft (610 mm) thick layer of peat. The system was constructed to simulate actual FDOT District 2 site conditions. The pavement system was constructed inside a Florida Department of Transportation (FDOT) Soil Box located at the University of Florida (UF). Site characterization measurements and observations were recorded before, during, and after the stabilization process. This paper outlines the study methodology, insitu testing protocol followed, and presents the findings and visual observations of the de-constructed soil box.
