Ten year performance evaluation of unbonded concrete overlay and Jointed Plain Concrete Pavement: A Toronto case study

Heavy, slow moving traffic can be extremely damaging to asphalt pavements. The City of Toronto was observing the rapid deterioration of the pavements at an urban intersection with high volumes of transit bus traffic. The heavy traffic was causing severe rutting and other safety concerns. Despite regular maintenance and rehabilitation interventions, the distresses were regularly recurring. In collaboration with the Cement Association of Canada, the City of Toronto elected to rehabilitate the high traffic intersection of Bloor Street and Aukland Road using Portland cement concrete materials in order to mitigate the existing problems. As part of this project, the city constructed its first unbonded concrete overlay and reconstructed an adjacent area as a conventional Jointed Plain Concrete Pavement. The rehabilitation activities were completed during the summer of 2003. Owing to the trial nature of these rehabilitation treatments in Toronto, instrumentation was installed by University of Waterloo researchers to monitor and evaluate the long-term performance of the rehabilitated pavements. This paper presents an overview of the existing conditions, design, construction and instrumentation of the Bloor and Aukland site and a ten year performance evaluation of the rehabilitated pavements. The results of this study show that concrete overlays and inlays are excellent rehabilitation options for urban pavements subjected to high volumes of heavy traffic. Both the unbonded overlay and Jointed Plain Concrete Pavement sections have demonstrated excellent performance to date. The pavements are in very good condition visually, ride quality remains excellent and the recurrence of the regular rutting and shoving problems that were being observed prior to rehabilitation has been mitigated. Significant remaining life is expected from the concrete pavement sections at Bloor and Aukland.