Nondestructive In Situ Characterization of Elastic Moduli of Full-Depth Reclamation Base Mixtures

Abstract

State highway agencies are searching for more cost-effective methods for rehabilitating roads. One sustainable solution is full-depth reclamation (FDR), which is a pavement rehabilitation technique that involves pulverizing and reusing materials from existing distressed pavements in place. However, there is little information on the long-term properties of these recycled materials. An important property, the elastic modulus, indicates the structural capacity of pavement materials and is highly recommended for design purposes by the Mechanistic–Empirical Pavement Design Guide. The elastic modulus directly affects selection of the overall pavement thickness; therefore, an accurate estimation of the modulus is key to a cost-effective pavement design. This research investigated the elastic modulus trends of three in-service pavements rehabilitated with the FDR technique during the 2008 Virginia Department of Transportation construction season. Foamed asphalt (2.7% with 1% cement), asphalt emulsion (3.5%), and portland cement (5%) were used as stabilizing agents for the FDR layers. The results of the moduli measured for the recycled base materials varied significantly over time. These changes were attributed to curing after construction, seasonal effects, and subgrade moisture. The structural capacity of the pavements improved irrespective of the stabilizing agent used.