Plant and Laboratory Compaction Effects on Performance Properties of Plant-Foamed Asphalt Mixtures Containing RAP

It has been reported that the application of foaming mix asphalt technology in asphalt industry helps offset the increase in energy cost, global warming, and more stringent environmental regulation concerns through decreasing the energy consumption and emissions associated with conventional hot mix asphalt production. In this study, the objective was to conduct an investigation of plant and laboratory (e.g., after reheating) compaction effects on performance properties of plant produced foamed asphalt mixtures with various recycled asphalt pavement (RAP) contents. The main properties of failure temperature and $G^{*}/\sin \delta$ of recovered binders and compaction effort, air void, indirect tensile strength (ITS), tensile strength ratio, flow, rut depth, resilient modulus, and fatigue life of plant directly compacted specimens and laboratory reheated and compacted specimens were determined in this research. The experimental design included the warm mix (foamed) asphalt mixtures from four asphalt plants in South Carolina, containing two surface mixtures. A total of over 150 specimens and 36 fatigue beams were tested in this study. The test results indicated that, as expected, the recovered binders from laboratory reheated mixtures generally have higher failure temperatures and $G^{*}/\sin \delta$ values, and lower phase angles compared with the extracted binders from plant compacted mixtures. In addition, laboratory mixtures have greater gyration numbers and higher air voids than plant mixtures. Moreover, higher ITS values, lower rut depths and resilient modulus values can be found from laboratory compacted specimens regardless of the asphalt plant site. Furthermore, fatigue life values varied from mixtures obtained from different asphalt plants.