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Warm mix asphalt (WMA) technology has gained popularity in recent years because of its ability to enhance mixture compaction at relatively low temperatures and to improve environmental sustainability. The role of WMA in sustainable pavement technology means that there is a need for comprehensive research in relation to its field performance. The objective of this study was to evaluate the field performance of WMA pavement sections that have been in service for five to eight years. Four rehabilitation projects were evaluated throughout the State of Louisiana. The study included field and laboratory experiments. In the field experiment, WMA test sections were evaluated along with companion conventional hot mix asphalt (HMA) mixture sections on each project. Pavement performance indicators (rutting, roughness, and cracking) from the Louisiana Pavement Management System (PMS) were analyzed. The laboratory experiment consisted of evaluation of mixtures from each project to determine mechanical performance indicators such as loaded wheel tracking (LWT) rut depth, flow number, semi-circular bend energy release rate (SCB Jc), and dissipated creep strain energy (DCSE). An analysis was conducted to rank the capability of laboratory mechanical performance properties to predict field performance. Generally, WMA test sections were found to exhibit similar or better rutting and cracking performance compared with their companion control HMA sections. In addition, the LWT rut depth was found to be a better indicator of field rutting performance than the flow number parameter. It is worth noting that the SCB Jc parameter was found to correctly rank more field cracking indicators than the DCSE parameter and therefore it may be a better indicator of field cracking performance.

The objective of this study is to compare the long-term aging performance of dry-processed rubber-modified asphalt mixture with styrene–butadiene–styrene polymer-modified asphalt mixture on heavy traffic volume roads in the wet-freeze environment of Michigan. The rutting performance was evaluated using the Hamburg wheel track device. The disc-shaped compact tension test was used to assess the fracture energy. The dynamic modulus experiment was used to estimate the load and displacement relationship. The asphalt binder properties were evaluated using multiple stress creep recovery and the linear amplitude sweep test. The pavement distresses were evaluated using the pavement mechanistic–empirical design. All three types of asphalt mixture show excellent rutting resistance after long-term aging conditions, while the fracture energy of the rubber mix is 17.1% to 30.5% higher than that of the control mix and 6.8% to 9.1% higher than that of the polymer mix. The rubber and polymer incorporated with the asphalt binder improved the resistance to permanent deformation and improved the fatigue life of the asphalt binder. In summary, the rubberized asphalt technology using the dry process shows better cracking resistance and fatigue life. Therefore, rubberized asphalt using the dry process will exhibit adequate performance when used for high-volume roads in the wet-freeze environment of Michigan.

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