Life cycle assessment of asphalt: a focus of end of life and reclaimed asphalt pavement (RAP)

Abstract

Asphalt is an important product of oil refineries-that is extensively used for road pavement. When an asphalt concrete pavement reaches the end of its designed life, the road surfacing is milled, creating a milling waste material known as re-claimed asphalt pavement (RAP) containing aggregate and asphalt binder. In this study, a cradle-to-grave life cycle assessment (LCA) was performed to evaluate the environmental impacts of hot-mixed asphalt (HMA) and warm-mixed asphalt (WMA) in terms of global warming potential (GWP) and energy input, with a focus on different end-of-life management scenarios of the asphalt pavement and the use of RAP. The study scope covered the entire life cycle of asphalt including raw materials, production, pavement (use) and end of life. The studied end-of-life processes were reuse (cold in-place recycling), recycle (hot in-place and in-plant recycling) and landfill (disposal). The functional unit was set to be 7 m x i km x 0.05 m of road pavement. The inventory data were collected from both primary and secondary data and analyzed by using commercial LCA software, Sima Pro 7.3. The results show that recycling is the best end-of-life management for asphalt pavement. WMA has better performance than HMA in both GWP and energy consumption, but the bene- fits are not significant (<5 %). The comparison between the BAU (business as usual) case and the best case of HMA and WMA revealed a reduction of energy consumption by ~8 % and GHG emission by ~22 %.