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

Abstract

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.