Toward Reliable Benchmarking of Concrete’s Global Warming Potential: Comparing EPDs and Concrete Mixes in Colorado at a Roadway Network Level

Buy Clean policies in the United States are gaining traction in the form of public procurement initiatives aimed at reducing the carbon footprint of publicly funded construction through the purchasing of lower-emissions building and roadway materials. These policies typically require benchmarking the global warming potential (GWP) of construction materials for eligibility on public projects. To do so, agencies must assess the current environmental performance of their material supply chains to set informed benchmarks while maintaining constructability. With the enactment of Buy Clean Colorado, which extends procurement requirements to transportation infrastructure, verifying GWP through environmental product declarations (EPDs) has become necessary. This study proposes a cradle-to-gate (A1–A3) GWP benchmarking methodology that categorizes concrete mixtures based on agency use categories and performance specifications yielding three mixture types. A limit value dataset was created using EPD data linked to Colorado Department of Transportation (CDOT) concrete products. A separate reference value dataset was developed from internal CDOT mix design data and estimated placement quantities. Two versions of the reference dataset, unweighted and consumption weighted, were generated. GWP results were expressed in quantiles for comparison with national benchmarks and regional industry reports. An analysis of concrete manufacturing emissions (A3) found higher A3 values in rural locations of Colorado as compared with urban locations. The consumption-weighted analysis revealed substantial differences from the unweighted case, especially for pavement mixtures, highlighting the importance of incorporating material use quantities for more representative benchmarking.