Geogrid Reinforcement to Reduce Pavement Section Thickness: A Case Study

The City of Twin Falls, Idaho constructed a geogrid-reinforced pavement section at the intersection of Washington Street and Filer Avenue in 2001. The Idaho Transportation Department (ITD) performed falling weight deflectometer (FWD) tests on this section of roadway after it was placed into service. The FWD data were analyzed to evaluate the benefits of the geogrid reinforcement. This paper describes the case history, analysis of the FWD data, and conclusions and recommendations regarding the use of geogrid reinforcement in this application. The results of the analysis were method dependent. Analysis of the FWD data using one method showed no benefit for the geogrid reinforcement, while a second analysis method concluded that the base course thickness could be reduced by about 20 percent. The most important observation is that a control section is absolutely critical to evaluating the benefit of geogrid reinforcement.