Assessment of Full-Depth Reclamation (FDR) pavement performance: A case study in Georgia

Full-Depth Reclamation (FDR) Pavements with a cement-stabilized layer are considered as semi-rigid structures. Although many state highway agencies across the United States have adopted the Mechanistic-Empirical Pavement Design Guide (MEPDG), the local calibration factors for semi-rigid pavements are not properly developed and validated for this design method. Consequently, state and local highway agencies still reference the AASHTO 72/93 guides when FDR pavements are designed. Both AASHTO 72/93 guides and MEPDG utilize the Unconfined Compressive Strength (UCS) to determine layer coefficients and the elastic modulus of the cement-stabilized layer. Several UCS-based moduli models exist for different chemically stabilized layers, but their reliability has not been sufficiently validated for FDR pavements. This paper aims to verify design inputs for FDR pavements through a forensic study conducted at four pavement sections in Georgia. Falling Weight Deflectometer testing was the primary tool used to determine suitable structural layer coefficients for FDR base layers. To assess the mechanical characteristics of FDR, including UCS, elastic modulus, and flexural strength, field cores, along with pulverized asphalt and base mixes, were collected. Test results were then compared with predictions from existing UCS-based models for elastic modulus and modulus of rupture. To understand how input variables affect the anticipated performance of FDR pavements, a mechanistic sensitivity analysis was carried out. While the structural layer coefficients based on the effective structural numbers were about twice as large as the values derived from the UCS values of the field cores, the layer coefficients derived from the UCS values of the field cores closely matched those typically assigned to chemically stabilized layers by many state highway agencies.