Institute for Transportation

About the research

The objectives of this study were to document the performance of roads using full-depth reclamation (FDR) and stabilized FDR (SFDR) in Minnesota, help develop SFDR design parameters appropriate for Minnesota, provide information on FDR/SFDR design procedures and specifications from beyond Minnesota, share current Minnesota FDR practices, and catalog the characteristics of some FDR/SFDR roads. A comprehensive literature review of FDR/SFDR projects and case studies was conducted, and an online survey was distributed to Minnesota local road agencies to determine the stabilizing agents used for SFDR projects. Eighteen FDR/SFDR test sections from eight counties were then selected for a case study, and performance data and core samples were collected for the sections. Minnesota gravel equivalency (GE) analysis was performed to back-calculate the granular equivalent factor for FDR/SFDR layers based on the design equivalent single axle loads (ESALs) and R-values for subgrade soils. The back-calculated GE values indicate that designers have likely been using GE values for FDR/SFDR layers that are consistent with current recommendations. It is recommended that the current GE values be generally retained for FDR/SFDR design. However, when slower-moving vehicles are the critical design consideration, relatively robust performance of FDR/SFDR layers may be expected. Visual distress surveys indicated that the FDR/SFDR bases studied are performing well in terms of destroying crack patterns that are often reflected through traditional hot mix asphalt (HMA) overlays. Therefore, decision makers may want to consider the use of FDR/SFDR as a base for reasons other than structural capacity.