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.

Evaluation of Bonded Concrete Overlay of Asphalt under Accelerated Loading

“…section were longitudinal cracks rather than corner cracks. This matches well with the current mechanical-empirical BCOA design method ( 4 ). On the other hand, more corner cracks were found on the 2-in.…”

“…Typically, the distressed AC pavement is milled and cleaned which helps to create a bond between the AC layer and the concrete overlay. The bonded layers promote the composite action of the pavement section, benefiting from the structural capacity of the existing AC layer (1)(2)(3)(4). Additionally, a short joint spacing is typically used, which reduces the flexural and curling stresses of the overlay and the debonding of the concrete and the asphalt at early ages (5).…”

“…Following the success of this project in Kentucky, several other BCOA projects were conducted across the United States (6). Several studies have been carried out to investigate the performance of BCOA under both in-situ conditions and controlled environments in accelerated research facilities (4)(5)(6)(7)(8). A recently conducted APT experiment in California indicated that a well designed BCOA on top of an AC layer could provide 20 years of service life on most of California's roadways (9).…”

“…Many methods for the BCOA design have also been proposed in recent decades ( 14 – 18 ). As pavement design has evolved from empirical design to mechanistic-empirical design in recent years, Vandenbossche et al ( 19 ) developed a mechanistic-empirical design procedure which has been recently implemented in the AASHTOWare Pavement ME software ( 4 ).…”

Havaalanı Kaplamalarını Asfalt ve Beton ile Yeniden Kaplamanın Karşılaştırmalı Dizayn ve Ekonomik Analizi

“…On the other hand, unbonded concrete overlays are applied on an existing surface with moderate or severe distresses, where existing surface layer is treated as a stable base, so existing surface layer is not counted as a structural surface element in the overlay design. Unbonded concrete overlays are used as minor or major rehabilitation options (Harrington and Fick 2014, Bhattacharya et al 2017, Vandenbossche and Fagerness 2002. Both bonded and unbonded concrete overlays have subcategories depending on the type of existing surface layer (Figure 1).…”