Analysis of Full-Depth Reclamation Trial Sections in Virginia

About the report:

Full-depth reclamation (FDR) has become an increasingly common technology to restore the service life of pavement structures requiring deep rehabilitation and to stretch available funding for pavement rehabilitation.  FDR consists of pulverizing the existing bound flexible pavement layers along with a portion of the unbound layers (or all the unbound layers and a portion of the subgrade); adding a stabilizing agent; compacting the mixture; and surfacing with a new bound material layer(s) or surface treatment.  FDR has been successfully demonstrated by many highway agencies.  However, the results of structural characterization and life-cycle cost analysis (LCCA) vary greatly, making it difficult to implement the results of previous studies directly as typical values for future pavement designs.

This study assessed the condition of three FDR trial sections constructed by the Virginia Department of Transportation (VDOT) during the 2008 construction season.  The sites were on SR 40 (Franklin County), SR 13 (Powhatan County), and SR 6 (Goochland County).  The test site on SR 40 used asphalt emulsion and foamed asphalt binder as the respective stabilizing agents on two sections within the project.   The test sites on SR 13 and SR 6 used portland cement as the stabilizing agent.  Following reclamation, all three sites received a hot-mix asphalt overlay.  The FDR assessment was conducted using a variety of methods that included gradation analysis; determination of resilient modulus, dynamic modulus, and indirect tensile strength; ground-penetrating radar; falling-weight deflectometer testing; and LCCA.  A hypothetical LCCA was also conducted to document the potential cost savings between a pavement rehabilitation schedule that included FDR with one that was based solely on traditionally used rehabilitation techniques.

The study showed that pavements could be successfully reconstructed using FDR and that the structural capacity of FDR sections was dependent on both the stabilizing agent and time.  The study recommends that VDOT pursue additional FDR projects where appropriate and work on refining a list of criteria to select future projects for those pavements where it is most suitable.  Further, a project-level investigation should be performed on any potential FDR site to verify that it is an appropriate candidate.  The LCCA showed that if a pavement rehabilitation strategy that includes FDR is applied to a preliminary candidate list of projects on VDOT’s primary and secondary networks, a 50-year life-cycle cost savings of approximately $10 million and $30.5 million, respectively, is possible when compared to a traditionally used pavement rehabilitation approach.  If the potential cost savings were annualized, the savings to VDOT would be approximately $463,000 and $1.42 million per year for the primary and secondary networks, respectively.

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