Characterization of Recycled Asphalt Pavement Materials for Use in Hot-Mix Asphalt Mixes

The use of recycled asphalt pavements (RAPs) has been a common practice in recent times owing to the sustainability aspect as well as the cost savings. Characterization of RAP is a challenging task because of the high variability in RAP, which can be associated with several factors such as the source, milling method, and processing techniques. RAP material characterization requires a sophisticated material testing facility and is time-intensive. A round-robin test organized by the International Union of Laboratories and Experts in Construction Materials, Systems, and Structures (RILEM) Technical Committee 237-SIB has resulted in a new characterization protocol that is primarily intended for new construction, rehabilitation, and maintenance requirements of pavements utilizing RAP. The current study has adopted the RILEM recommendations to categorize RAP from various sources using basic tests: gradation and cohesion. RAPs obtained from seven sources, including artificially aged RAP, were investigated in the current study, and the tests were carried out on 100 % RAP. The allowable proportion of RAP that could be used for the hot-mix asphalt mix design was computed for all seven RAP sources using the blending charts. Furthermore, significant correlations were obtained between the allowable RAP content and the cohesion indices. The observations from this study suggest that basic tests, such as cohesion tests, can reduce the need for complicated test procedures to some extent and can be very advantageous for extensive field projects using RAP.