Quantitative evaluation on the energy saving and emission reduction characteristics of warm mix asphalt mixtures

In response to global environmental protection policies, and the imperatives of achieving carbon peaking and carbon neutrality goals, warm mix asphalt (WMA) technology garnered increasing prominence in the field of pavement engineering. This study conducted a quantitative assessment of the energy-saving and emission reduction characteristics of WMA mixtures throughout their lifecycle, encompassing the production and construction phases. To achieve this, 70# asphalt, SBS modified asphalt, Alube@, and ACMP@ WMA mixtures were selected, and their optimal mixing temperatures were determined through the rigorous variable speed mixing test. We formulated calculation models for energy consumption and carbon emissions at each stage, and incorporated a self-developed variable temperature emission test to measure the CO2 emissions resulting from asphalt heating volatilization. The findings revealed that the two warm mix additives effectively lowered the mixing temperature of 70# asphalt mixture by 25-26 degrees C. Comparatively, it was estimated that WMA mixtures exhibited reductions in energy consumption ranging from 16.5 % to 23.0 %, 11.3 % to 36.5 %, and 15.4 % to 47.4 % during the raw material heating, mixing, and compaction processes, respectively, when compared with the two hot mix asphalt (HMA) counterparts. Moreover, the noteworthy reductions in carbon emissions stemming from fuel combustion and asphalt heating volatilization were observed for the WMA mixtures. On-site measurements further corroborated that the WMA mixtures clearly manifested pronounced energy-saving and emission-reduction effects during the production and spreading phases. In conclusion, WMA is an environmentally friendly technology with promising prospects for widespread applications.