Evaluation of sustainable technologies that upgrade the binder performance grade in asphalt pavement construction

There are many technologies to produce sustainable asphalt pavements that may affect various phases of pavement life. Therefore, it is difficult to choose the most appropriate technology that addresses all the engineering requirements, especially in the technologies produce the identical outputs. In this study, a PG64 asphalt binder (base binder) was upgraded to PG70 (target binder) through incorporation of two different sustainable approaches: (1) synthetic wax and (2) recovered binder from reclaimed asphalt pavement (RAP). The effects of the different modification methods were evaluated in terms of the engineering properties of materials and the sustainability features of mix production. The results indicated the modified binder (as outputs) have the same performance grade as the target binder, but the incorporation of RAP reduces the environmental pollutants at the stage of raw material processing, while the use of the wax decreases the pollutants during asphalt mix production. Consequently, the selection of the type of sustainable technology for production of cleaner asphalt pavement depends significantly on the stage desired to be modified in the pavement construction. A few scenarios and a new method are also proposed as a guide to selection of the appropriate sustainable approaches based on the binder and engineering properties.