Cradle-to-pavement carbon footprint and biogenic carbon accounting of bio-extended bituminous binders for asphalt pavements

The carbon footprint of bio-extended bituminous binders aiming for pavement decarbonisation was quantified using a “cradle-to-pavement” life cycle assessment. The binders were extended with a plant-based bio-oil. By biogenic carbon accounting, the impact of biogenic carbon flow was analysed through different approaches. The results indicated that using the bio-oil as a bitumen extender slightly increases the fossil global warming potential (GWP) of asphalt pavements, by about 1%. Both the absolute GWP levels and the effect of polymer modification on average annual GWP are variable, depending on the input data. When the “−1/+1” approach is adopted, two of the three analysed cases showed a lower average annual GWP of asphalt pavements with polymer-modified bitumen while one analysed case showed almost unchanged average annual GWP. All analysed cases confirmed that the biogenic carbon accounting by the “−1/+ X” approach reduces the total and average annual GWP significantly for the cases with biogenic components.