Field Performance and Cost-Effectiveness of Ultrathin Asphalt Overlay in Hot and Humid Climates.

A pavement maintenance treatment that has increased in popularity in recent years is ultrathin overlay (UTO). While the selection and construction processes for UTO has been well researched in previous studies, few studies assessed the field performance and cost-effectiveness of UTO especially in hot and wet climates. Therefore, the objective of this study was to evaluate the field performance and cost-effectiveness of UTO projects in Louisiana. To achieve this objective, asphalt pavements in Louisiana that received UTO were monitored for up to 14 years. The performance and cost-effectiveness of these sections were evaluated in terms of pavement condition Index (PCI), alligator cracking index (ALCR), rutting index (RUT), random cracking index (RNDM), and roughness index (RUFF). Results showed that UTO extended the pavement service life (PSL) by 8.7, 9.1, 7.0, 9.7, and 9.5 years, on average, for PCI, RUFF, RNDM, ALCR, and RUT, respectively. This extension varied based on the pretreatment pavement conditions and traffic level. As such, a predictive model was developed, with reasonable accuracy, to predict the extension in PSL of UTO based on project conditions. Results of the cost-benefit analysis indicated that UTO was cost-effective in most of the cases. The findings of this study were incorporated into a decision-making tool to assist transportation agencies in hot and humid climates determine the expected immediate and long-term field performance as well as the cost-effectiveness of UTO based on their project conditions. This will help these agencies make effective decisions for the maintenance and rehabilitation of their pavements. [ABSTRACT FROM AUTHOR]