Optimal Timing for Preventive Maintenance for Addressing Environmental Aging in Hot Mix Asphalt Pavements (TPF-5/153)

One of the major tasks in any transportation agency pavement management system is to select appropriate options for rehabilitation and maintenance. The goal of this study is to determine the proper timing of preventive maintenance treatments in order to optimize life cycle costs and pavement performance. Environmental aging of the asphalt binder in the underlying pavement is not well understood, and this project seeks to better understand the aging mechanism and how it can be reduced through pavement preservation.

This research requires a mixture of fundamental analyses based on laboratory experiments and field investigations. The timing of the surface treatment is related to the aging and distresses that develop in asphalt pavements over time. Ideally, a surface treatment should be applied at the proper time to provide a balance between maximum life and minimum cost. The progression of the asphalt pavement surface condition is mostly related to the aging characteristics of the asphalt binder and to the evolution of the mechanical properties of the binder with aging. An ongoing project at the University of Minnesota is investigating some of the issues related to the application of surface treatments, including environmental (climatic) modeling and mixture and binder testing to determine when preventive maintenance activities should be done. 

The research in this pooled fund study aims to fill several gaps in current knowledge. Few if any studies have examined the pavement performance after placing a preventive maintenance treatment immediately after construction (year 0), but this could be accomplished in this study. Many of the existing studies monitor pavements under live traffic loadings. This study hopes to examine strictly environmental aging by either leaving pavement sections without traffic or by studying shoulders for their performance under various preventive maintenance treatments. MnROAD has the potential to be only the second site in the country that would apply surface treatments to a pavement with known properties at various times to study the effects of the surface treatments on aging. Finally, MnROAD provides a unique opportunity to study pavements with detailed weather information and known traffic applications in a safe and controlled work environment. The ability to divert traffic allows researchers to monitor and sample test sections in a safe manner, and it encourages researchers to push the envelope and try something new without causing a major disruption to the traveling public if it fails prematurely.