Full Depth Reclamation as an Adaptation Approach to Flood Resilience

Abstract

Flooding presents a massive threat to asphalt pavement performance as moisture inundation into the pavement structure can cause a reduction in strength, stiffness, and structural capacity. Full Depth Reclamation (FDR) is a rehabilitation technique that is able to improve the flood resilience of pavements through the stabilization of the existing materials. This study, in connection with the Virginia Department of Transportation (VDOT), evaluates the moisture susceptibility and structural performance of various FDR mixtures stabilized with portland cement, foamed asphalt, and asphalt emulsion. The mixtures developed were based on three different blends of material, representative of that found in Virginia. Laboratory mix designs were developed based on VDOT specifications and evaluated using unconfined compressive strength (UCS), indirect tensile strength (ITS), and resilient modulus (MR) tests. The moisture susceptibility of each blend was assessed after testing specimens with and without moisture conditioning. Moisture conditioning was completed for UCS and ITS tests by submerging compacted samples into a temperature controlled water bath for 24 to 72 hours prior to testing. Back-saturation was used to moisture condition MR specimens until no further increase in saturation level could be achieved. Results showed that cement-stabilized FDR exhibited negligible reductions in strength and stiffness after saturation while foamed asphalt-stabilized FDR experienced approximately 30% reductions in both. Asphalt emulsion-stabilized FDR displayed similar reductions in strength, approximately 30%, based on the saturated and unsaturated ITS results. However, reductions in MR were recorded as 15% or less. For all stabilizing agents, any moisture-induced damages occurred within the first 24 hours of saturation as there was minimal difference between one day and three day conditioning periods. The resilient modulus results were inputted into AASHTOWare Pavement ME Design to assess the long-term pavement performance of pavement structures with and without an FDR layer. The modeling results showed that pavement structures including an FDR layer outperformed a typical asphalt pavement of a similar thickness, regardless of the stabilizing agent used. Each model was run at unsaturated and saturated conditions in which the results showed that cross sections with a stabilized FDR layer successfully enhance the flood resilience of pavement structures.