Global Warming Potential Benchmarking of Asphalt Mixtures to Support Low-Carbon Procurement and Cradle-to-Gate Life Cycle Assessment-Based Strategies to Reduce Mix Global Warming Potential

Considering the recent emphasis on low-carbon construction materials, there has been a growing focus on quantifying the environmental impacts associated with asphalt mix production. The global warming potential (GWP) of an asphalt mix is being used to establish reference/target values to support possible implementation of low-carbon procurement strategies. This paper covers two important aspects related to this topic. First, the paper discusses different benchmarking approaches that can be adopted to establish reference GWP values for asphalt mixes. Three possible approaches are presented, and their respective advantages and disadvantages are discussed. Results from an extensive case study are also presented, where the different benchmarking approaches have been used along with mix design data specific to the state of Oklahoma. The importance of establishing different reference values based on mix classes has also been highlighted. The second part of this paper explores different strategies to lower the GWP of asphalt mixes. Results from a cradle-to-gate life cycle assessment (LCA) study are presented, focusing on GWP quantification of asphalt mixtures when two commonly advocated strategies, balanced mix design (BMD) and reduced-temperature warm-mix asphalt (WMA), are implemented. BMD implementation allows for increased usage of reclaimed asphalt pavement (RAP) in asphalt mixtures. WMA technology helps reduce the plant production temperature, which leads to sizable reductions in burner fuel consumption. Results from the LCA study highlighted that ∼10% reduction in asphalt mix GWP can be realized (compared with traditional Superpave-based approaches) through combined implementation of BMD and WMA technologies.