Bipartisan Infrastructure Law Series

Aligning your Department’s Priorities with BIL Funding Priorities

The IGGA will be bringing you a multi-part series in 2023 to help your organization design and specify projects that meet the intent of BIL funding.

May Spotlight: Carbon Capture

Concrete’s natural ability to capture carbon helps meet the intent of the Carbon Reduction Program (CRP), established by the BIL.

BIL Funding

The CRP provides funds for projects designed to reduce transportation emissions. Some funds require states to develop carbon reduction strategies. These strategies may include quantifying the total carbon emissions associated with the production, transport, and materials used in the construction of transportation facilities. (Read more guidance from the FHWA here.)

Concrete Captures Carbon

While new technologies and modes of transport receive a lot of attention as carbon-reducing strategies, traditional pavements—specifically, concrete pavement—can also offer sustainability benefits. In addition to carbon-reducing changes being made at the materials production level, along with the fuel-saving benefits of smooth concrete pavements and concrete’s long life (which both reduces use of raw materials and confers the benefit of resilience), in-service concrete is known to contribute to carbon neutrality by absorbing atmospheric carbon.

This carbon capture, known as carbonation, occurs when hydrated portland cement is exposed to atmospheric CO2, which reacts with the water and calcium compounds in concrete and produces calcium carbonate. Carbonation takes place over the lifetime of a pavement and while there is a risk of the rate of carbonation slowing over the years due to the pore-blocking effect of the calcium carbonates being formed, it is possible to remove the carbonated surface and expose a fresh, uncarbonated layer. The simplest way of doing this is by diamond grinding—a technique that is commonly performed as part of pavement preservation. Diamond grinding as often as every 10 to 15 years will enable a concrete pavement to restart the carbonation process and continue offsetting the carbon emitted by concrete production.

Introducing the CSHub Carbon Calculator

The amount of carbon offset achieved via carbonation can be impressive. According to the MIT CSHub, carbonation “has been estimated to offset up to 43% of calcination emissions that occur during cement production.” But how can one determine the actual amount of carbon capture that is occurring on a given stretch of concrete pavement? The answer is to quantify inputs, then perform the carbon accounting. To help with this, MIT’s CSHub has made available a material- and facility-specific calculator for carbon uptake in concrete. With its broad focus—initial concrete mixture, location and exposure characteristics during the concrete’s service life, and eventual stockpiling conditions—the tool can help users assess the true rate of carbon capture for a given area of installed concrete.

Access the Whole Life Cycle Carbon Update Tool

Stay tuned for our next installment of the IGGA series Aligning your Department’s Priorities with BIL Funding Priorities: Fuel Savings, coming in June.

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