Legislation could help lower concrete’s carbon footprint in Illinois: ‘It’s literally what the world is made out of’
Lawmakers and advocates are looking to offset greenhouse gas emissions from one of the world’s most consumed materials second only to water — concrete.
The building material’s main binding ingredient, cement, represents a whopping 7% to 8% of global carbon emissions. But experts say it’s not likely construction projects will slow down any time soon — or that a zero-emission replacement will crop up like EVs have for gas cars, for instance.
“A lot of areas that we look at about reducing emissions, we’re talking about transitioning or replacing things entirely, and concrete is just not going anywhere,” said Chris Neidl, a decarbonization policy consultant to environmental nonprofit Natural Resources Defense Council. “It’s so embedded in architectural construction practice, and we’re only going to use more and more of it.”
Rather than replace concrete, the leading solution is to transform it.
“An easy way to do that is to limit the amount of cement paste in concrete mixes,” said NRDC’s state industrial decarbonization lead, Mikhail Haramati. “Concrete is a recipe. It’s like baking a cake, essentially. And there are different recipes for different types of cakes, if you will, for different projects.”
Commonly used alternatives today include steel slag and fly ash — waste products generated from steel production and coal power generation.
“Slag and fly ash are, I would say, the most commonly used supplementary cementitious materials right now, but they are sort of in limited supply,” Haramati said. “That’s one of the reasons why we’re looking at alternatives to them. And they also come from the fossil fuel industry — in particular slag.”
One Buffalo Grove Democrat is hoping to follow in the footsteps of states like New Jersey and New York to pass a law that would incentivize the production and deployment of these reduced-emission options statewide.
Rep. Dan Didech introduced the Concrete Carbon Act earlier this year to address the “hard-to-abate, energy-intensive industry.” Didech said he hopes the legislation will be considered in this spring’s state budget discussions, scheduled to come to a close May 24.
“We think this is something that Illinois should pursue, as well. Big picture, I think climate change is a continuing threat that we need to do everything we can to mitigate the effects that we’re already seeing,” Didech said. “That means taking an all-of-the-above approach to reduce the amount of carbon that is emitted into the atmosphere.”
The legislation would establish a performance-based tax credit for concrete producers that use low-carbon materials and methods for state-funded projects. Because concrete would have to deliver quantifiable reductions in embodied carbon to qualify, the bill further requires the implementation of performance-based specification standards.
It also would direct the Illinois Department of Transportation to look at ways to accelerate the testing of new decarbonization methods and materials for concrete by the Materials Bureau.
“It’s a tough industry because it’s literally what the world is made out of, and you can’t play fast and loose with how you change rules around that,” Neidl said. “We’ve been making this material pretty much in the same way for a couple 100 years. If nobody is asking for change in this, then it’s going to just continue to be the same. That’s why it’s not going to happen unless there’s an incentive to do so.”
Neidl, who is the lead author of NRDC’s Design Guide to State and Local Low-Carbon Concrete Procurement, added that as major purchasers of concrete, state and local governments can step up in accelerating sector-wide embodied carbon reduction through their procurement choices.
“About 35 to 40% of (concrete) is actually bought by federal, state, local governments. Procurement can really be a major catalyst for driving change, just from a demand side,” he said.
Illinois Department of Transportation spokesperson Maria Castaneda said the agency routinely utilizes fly ash and slag, typically using concrete recipes that replace at least 25% of the cement when using fly ash and 30% when using slag.
In 2023, projects in Cook and the collar counties used about 360,000 cubic yards of concrete with slag used in 80% and fly ash in 20%. The materials resulted in savings of more than 20,000 tons and 5,000 tons of CO2 equivalent, respectively, when compared to traditional concrete.
“We anticipate our usage to increase this construction season due to Interstate 80 paving contracts, projected to use around 450,000 cubic yards of concrete,” Castaneda said in an email. “Almost all of this concrete will use slag resulting in 32,633 tons CO2 (equivalent) savings.”
• Jenny Whidden, jwhidden@dailyherald.com, is a climate change and environment writer working with the Daily Herald through a partnership with Report For America supported by The Nature Conservancy. To help support her work with a tax-deductible donation, see dailyherald.com/rfa.