Study on Carbon Emissions during the Construction Phase of Steel Slag Asphalt Pavement

Against the backdrop of the increasing scarcity of natural mineral aggregates and the underutilization of excessive steel slag resources, extensive research has confirmed the applicability of steel slag as a road aggregate and its favorable pavement performance properties. However, systematic quantitative assessments of steel slag asphalt pavement (SSAP) across multiple dimensions, including environmental and economic benefits, remain relatively limited. Among SSAP with 100% replacement of coarse aggregates by steel slag, the material production stage exhibits the lowest energy consumption and carbon emissions; this is followed by SSAP with a 60% steel slag replacement ratio, while conventional asphalt pavement (CAP) with 0% replacement demonstrates the highest values. When the transportation distance for natural aggregates is 180 km and for steel slag is 60 km, SSAP with 100% steel slag replacement shows the minimal energy consumption and carbon emissions during the transportation stage, whereas CAP with 0% replacement records the highest. Notably, this relationship reverses in the construction stage. The total carbon emissions generated during the construction period for SSAP with steel slag replacement ratios of 0%, 60%, and 100% are 142,841.16 kg, 122,775.15 kg, and 119,220.11 kg, respectively. Specifically, CAP (0% replacement) exhibits the maximum total energy consumption and carbon emissions during construction, while SSAP with 100% steel slag replacement presents the minimum values. These results demonstrate that replacing natural aggregates with steel slag can effectively reduce energy consumption and carbon emissions during the construction of asphalt pavements.