Comparative analysis of greenhouse gas emissions and energy consumption of composite cold-mixed asphalt mixture based on life cycle assessment

With the continuous impact of the greenhouse effect and energy crisis, the environmental assessment of asphalt mixtures is prosperous. Cold-mixed asphalt mixture is paid more attention as a greener and cleaner pavement material. However, the study on the environmental impact of cold-mixed asphalt mixture is lacking. In this study, the greenhouse gas (GHG) emissions and energy consumption of the composite cold-mixed asphalt mixture (CCMA) have been quantified from cradle to grave by the life cycle assessment, and compared with the counterparts of hot-mixed asphalt mixture (HMA). The crucial stages are identified based on their contribution to life cycle GHG emissions and energy consumption. Three alternatives are considered, and their potential for GHG emissions reduction and energy sustainability are discussed. The results show that the GHG emissions and energy consumption of CCMA are respectively 13.56 kg carbon dioxide equivalent and 4.61 kg coal equivalent over the life cycle. In comparison with HMA, the GHG emissions of CCMA are reduced by 74.3 % and the energy consumption by 41.6 %. The materials production stage is crucial, accounting for approximately 57.2 % of emissions and 48.4 % of energy demand over the entire life cycle. Optimizing mixing temperature, using recycled asphalt pavement and promoting electricity can achieve different scales of energy saving and emission reduction.