Transverse joint faulting is a common distress in bonded concrete overlays of asphalt pavements (BCOAs), also known as whitetopping. However, to date, there is no predictive faulting model available for these structures. To account for conditions unique to BCOA, a computational model was developed using a three-dimensional finite element program, ABAQUS, to predict the response of these structures. The model was validated with falling weight deflectometer (FWD) data from existing field sections at the Minnesota Road Research Facility (MnROAD) as well as at the University of California Pavement Research Center (UCPRC). A large database of analyses was then developed using a fractional factorial design. The database is used to develop predictive models, based on artificial neural networks (ANNs), to rapidly estimate the structural response at the joint in BCOA to environmental and traffic loads. The structural response will be related to damage using the differential energy concept. Future work includes the implementation of the developed ANNs in this study into a faulting prediction model for designing BCOA.

A statistical classifier was developed to interpret falling weight deflectometer data for the detection of voids under jointed concrete pavement slabs. The classifier was trained with the Seasonal Monitoring Program sections in the Long-Term Pavement Performance (LTPP) database and data from the Minnesota Road Research Facility. A two-level cross-validation process was used to assess the performance of existing void detection methods, according to a threshold of a single variable, and the least absolute shrinkage and selection operator (LASSO) classifier, which is based on several variables. Simple void detection methods based on the normalized 9,000-lb deflection were found to perform better than void detection methods based on variable deflection analysis. The LASSO classifier outperformed any of the existing void detection techniques. The LASSO classifier was validated through two field trials in Pennsylvania and an LTPP general pavement section in which significant faulting had developed.

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Reflective cracking can be a concern in unbonded concrete overlays of existing distressed concrete pavements. In these structures, an interlayer, commonly hot-mix asphalt (HMA) or a nonwoven geotextile fabric, is placed to isolate the overlay concrete from the existing concrete pavement. The interlayer minimizes interaction between the overlay and the existing concrete pavement, which helps prevent distress in the existing pavement from propagating into the overlay. In this study, a laboratory investigation was used to examine the influence of HMA and geotextile fabric interlayer systems on the potential for development of reflective cracking. A laboratory test was conducted by using stacked beam specimens separated by an interlayer to evaluate the potential for a discrete crack in the lower beam reflecting up through the interlayer and into the overlay beam. The study revealed that reflective cracking was more likely when there was loss of support beneath the existing pavement. Reflective cracking did not occur with any of the interlayer systems when the beam was fully supported. The nonwoven geotextile interlayers that were tested were more effective than the HMA interlayers at preventing reflective cracking. Even though the fabric interlayer had a higher load ratio than the HMA interlayers, a relatively large load was required to generate reflective cracking regardless of the interlayer type (HMA or fabric) and, therefore, both may be suitable interlayer alternatives for the prevention of reflective cracking.

Bonded concrete overlays of asphalt pavements (BCOA) consist of a concrete overlay placed on an existing asphalt or composite pavement. This technique is intended as a cost-effective rehabilitation solution for marginally distressed in-service asphalt or composite pavements. BCOA with panel sizes between 4.5 ft and 8.5 ft have become popular as they reduce curling stresses while keeping the longitudinal joints out of the wheelpath. The BCOA-ME (mechanistic empirical) design procedure and Pavement ME short jointed plain concrete pavement (SJPCP) module can both be used to design BCOA with mid-size panels. However, these design procedures differ in the assumptions used to develop the mechanistic computational model, fatigue models used to predict failure, treatment of environmental conditions, estimate of asphalt stiffness, consideration of structural fibers, the application of traffic loading, and the calibration process. This results in the procedures producing different overlay thicknesses and predicted distresses. The strengths and limitations of each procedure are evaluated and comparisons are made between the design thicknesses obtained from them.