This paper describes modifications made to the Mechanistic-Empirical Pavement Design Guide (MEPDG) to accommodate the design of newly constructed composite PCC-PCC pavements. In previous versions of the MEPDG, a newly constructed PCC-PCC pavement project was considered as a bonded PCC overlay of an existing PCC pavement. Due to this simplification, the MEPDG was not self-consistent in its predictions for a newly constructed PCC-PCC pavement and its structurally equivalent single-layer analogue. To remedy this inconsistency, researchers suggested modifications to the Enhanced Integrated Climatic Model (EICM) used by the MEPDG in terms of 1) the number of locations through the slab used by EICM to determine the thermal gradient and 2) the EICM calculation of the subgrade spring stiffness (or k-value). The paper includes "before and after" MEPDG sensitivity analyses to justify the modifications developed and implemented into the MEPDG with the assistance of the MEPDG development team. This research was conducted under the Strategic Highway Research Program (SHRP2) R21 Composite Pavements project.
TRB 2012 Annual MeetingPaper revised from original submittal.Tompkins, Saxena, Gotlif, and Khazanovich The R21 project "Composite Pavements" was developed by the second generation of the Strategic Highway Research Program (SHRP2) to investigate the design and construction of new composite pavement systems. One fork of the R21 research focuses on a composite pavement system featuring a thin portland cement concrete (PCC) layer placed over another PCC layer. In Europe, two-layer composite PCC pavements (PCC-PCC) are more commonly used than they are in the United States. For instance, the standard concrete pavement in Austria is constructed according to two-layer PCC specifications. Furthermore, composite PCC pavements have been used in countries such as Switzerland, Belgium, the Netherlands, France, and Germany, and composite PCC pavements are becoming even more popular as design and construction techniques are refined further (1). The goals of the SHRP2 R21 research were to determine the behavior and identify critical material and performance parameters for PCC-PCC; develop and validate performance models and design procedures consistent with the Mechanistic-Empirical Pavement Design Guide (MEPDG); and recommend specifications, construction techniques and quality management procedures.In adopting the MEPDG for the design and analysis of newly constructed composite PCC-PCC pavements, an initial modeling simplification made by the MEPDG development team was to treat a newly constructed PCC-PCC composite pavement as a a bonded PCC-over-JPCP project. This change was implemented in MEPDG (beta versions 1.014:9030A and 1.206:R21), and research for the composite PCC-PCC portion of the R21 project that used the MEPDG simulated new PCC-PCC construction using a bonded PCC-over-JPCP project in the MEPDG.However, the decision to use a bonded PCC overlay project to mirror new PCC-PCC construction introduced a number of challenges in mode...