Implementation of the Thin Bonded Concrete Overlay of Existing Asphalt Pavement Design Procedure in the AASHTOWare Pavement ME Design Software

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This paper describes the implementation of the bonded concrete overlay of asphalt pavement mechanistic–empirical (BCOA-ME) design procedure, developed by the University of Pittsburgh, into the AASHTOWare Pavement ME Design software. The BCOA-ME procedure was generally compatible with the mechanistic–empirical framework of Pavement ME and thus adaptable into the design framework. A thin bonded concrete overlay of existing asphalt pavements includes short to medium joint spacings (typically 6 × 6 ft) and a strong bond or high-contact friction between the portland cement concrete slab and the existing asphalt concrete surface. As much of the theory, concepts, assumptions, and inputs in the BCOA-ME design procedure as possible were implemented into the Pavement ME software. Differences included those required to match the computational procedures of Pavement ME (e.g., axle load spectra versus equivalent single-axle loads, monthly asphalt concrete damaged dynamic modulus, monthly portland cement concrete strength and modulus, and monthly unbound material resilient modulus). Longitudinal joint spacing ranging from 5 to 8 ft (not <5 ft) was included. Longitudinal fatigue cracking was directly considered as in the BCOA-ME, which initiates at the bottom of the slab. The calibration of the longitudinal cracking transfer function produced excellent goodness-of-fit statistics with no significant bias. The new procedure was incorporated into Pavement ME Version 2.3, released in July 2016.