Description
As concrete overlays become an increasingly prevalent alternative for pavement preservation and rehabilitation, the need grows to understand their long-term performance and to predict service life. Since the late 1970s, more than 2,100 centerline miles of concrete overlays have been constructed on Iowa roadways. As an early adopter of this treatment strategy, particularly on the county highway system, Iowa has a significant number of overlays of all types, including bonded and unbonded overlays of existing concrete and asphalt pavements that have carried traffic for extended periods.
In this study, statistical approaches, including survival analysis with different distributions, are applied to analyze the performance of concrete overlays and predict their remaining service life. Historical construction, pavement performance, and traffic data were retrieved from the Iowa Pavement Management Program. Survival analysis is employed to estimate failure probabilities over time for pavement performance indicators (e.g., international roughness index (IRI), pavement condition index (PCI), transverse cracking, etc.) to reach specified thresholds. Also, the most critical performance indicator that is a threat risk for concrete overlays through their service life is identified. In addition, sensitivity analysis of design parameters including thickness, joint spacing, and traffic for Iowa concrete overlays is used to investigate the influence of each parameter on each pavement performance indicator.
