FHWA sets Low Carbon Materials Program Concrete Thresholds

Sources: Federal Highway Administration; CP staff

The Federal Highway Administration has published the driving metric—global warming potential (GWP), measured in kilograms of carbon dioxide equivalent per cubic yard (kgCO₂e/yd.)—attending nine concrete mix classes specified for cast-in-place or precast transportation pavements, elements and structures. The Concrete Thresholds tables provide GWP data that Low Carbon Transportation Materials (LCTM) Grants recipients require to meet Environmental Protection Agency criteria. Congress tasked EPA with such oversight as part of the Inflation Reduction Act, the LCTM funding source.

An FHWA Tech Brief, Development and Use of Embodied Carbon Benchmarks for Setting GWP Thresholds for the LCTM Grants Program, details the central nature of GWP metric reporting to obtain candidate project funding.

Based on NRMCA Industry Average Industry Average Environmental Product Declaration for Ready Mixed Concrete, the Concrete Thresholds tables present GWP figures for 2,500 to 8,000 psi normal weight and 3,000 to 5,000 psi light weight concrete in eight U.S. regions. Each region has average, 20^th percentile and 40^thpercentile GWP figures, consistent with EPA criteria for LCTM project grant approvals. Across a set of 216 thresholds, the GWP figures range from a low of 146.13 kgCO₂e/yd. for 2,500 psi normal weight concrete to 478.12 kgCO₂e/yd. for 5,000 psi light weight concrete, both in the Pacific Northwest Region 20^th percentile columns. The regional breakdown enables EPA and LCTM grant candidates to factor GWP variations indicative of cement and aggregate production methods and quality.