Life cycle energy and environmental assessment of warm-mixed asphalt (WMA)

Abstract

This study focused on evaluating the energy consumption and environmental performance of warm-mixed asphalt (WMA) technology as an alternative pavement to conventional hot-mixed asphalt (HMA) using lite cycle assessment technique (LCA). The scope included data collection analysis of energy and environmental impacts, and comparison between WMA and HMA. The system boundary covered provision of raw materials, asphalt production, transport. paving, maintenance and disposal (demolition or recycling) based on a functional unit of 7 m x 1 km x 0.05 m road pavement. The data of asphalt production and pavement were collected from actual sites and compiled by using commercial LCA software, SimaPro 7.3. After that, a life cycle impact assessment (LCIA) was performed to evaluate the environmental impacts, focusing on global warming potential (GWP) and energy input. The results were compared with HMA based on the same functional units and also with results from other studies. The results of this study showed that GWP. represented by greenhouse gases (GHG) emissions, came mostly from raw materials and asphalt production with only a small contribution from the transportation and pavement process. When compared to HMA, the results showed that WMA had better performance in both GWP and energy aspects. but the benefits were not significant (<5%). It is expected that more environmental benefits can be achieved if the mixing temperature is further decreased. In comparison to other studies, the energy and environmental performance of HMA and WMA in Thailand is not as good as those observed in other countries. Finally, the end of life phase is obvious that recycling process helps reduce both energy input and GWP impact such that the more recycle leads to the better environment performance of asphalt.