Can a new concrete mixture help reduce the construction industry's carbon footprint?

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Concrete is everywhere, right? We walk on it, drive on it, build our houses on it. But producing the ubiquitous construction material makes up a significant portion of global greenhouse gases that are emitted each year. Now researchers at the University of Illinois Urbana-Champaign think they might be one step closer to greener concrete. Juanpablo Ramirez-Franco from member station WNIJ explains.

JUANPABLO RAMIREZ-FRANCO, BYLINE: Ryan Cialdella is sitting in the Ozinga concrete laboratory based out of the ready-mix supplier's Chicago Chinatown location. The company's characteristic red-and-white-striped concrete trucks are coming in as soon as others are leaving. It's a busy day. But Cialdella says underneath it all, there's big changes coming to the industry.

RYAN CIALDELLA: The days of making concrete with just straight cement are gone. They're a thing of the past.

RAMIREZ-FRANCO: Cialdella explains that making concrete is relatively easy. You mix gravel, sand, water, cement, and there you have it, the basic recipe behind the planet's most-consumed material after water - concrete. But Cialdella says there's been a lot of interest around reducing the amount of cement used in any given mix, as it's by far the most carbon-intensive ingredient in concrete.

CIALDELLA: When you look at global emissions and the amount of cement that's produced worldwide, that's where you get that large number - 6 to 8% of greenhouse gas emissions from the cement industries.

RAMIREZ-FRANCO: The Ozinga laboratory tested a new low-carbon concrete mixture, developed by researchers at the University of Illinois Urbana-Champaign and Meta, that emits 40% less carbon emissions compared to the standard regional mix. Then the mix was deployed in non-critical areas of a Meta data center in DeKalb, Ill.

Lav Varshney helped develop the artificial intelligence models behind the novel concrete mixtures and teaches computer engineering at the University of Illinois Urbana-Champaign.

LAV VARSHNEY: Data centers are just very large buildings made of concrete. So that, just by itself, implies that they require a lot of embodied carbon.

RAMIREZ-FRANCO: Nishant Garg teaches civil engineering at the U of I, and he's another collaborator on this concrete project. He says the world produces about 4 billion tons of cement - a key ingredient in concrete - every year, and that adds up.

NISHANT GARG: And you can say roughly for every ton of cement that we make, we release about 0.8 tons of CO2.

RAMIREZ-FRANCO: So reducing the emissions from concrete is a necessity if Meta wants to hit its net-zero goal.

Amruta Sudhalkar works on the design and sustainability of the Meta data centers. She says that each one is huge - about a million square feet. Nationally, there are 17 of them. Three expansions were just recently announced at sites in Arizona, Ohio and here in DeKalb. Sudhalkar says that the concrete pilot in Illinois has been a success but that the low-carbon formulations aren't one-size-fits-all.

AMRUTA SUDHALKAR: And so you might see variation in how much carbon savings you're realizing, depending on the location and the quality and the availability of the materials that we're dealing with.

RAMIREZ-FRANCO: Nishant Garg says concrete is here to stay. It's central to contemporary life - used for building roads, sidewalks, bridges and foundations. So it's not going anywhere.

GARG: We wanted to build, let's say, a data center in this case. But then it was built with 5% less CO2 emissions. I think that's a worthy cause because saying that, let's not build it or let's just build it with, you know, the maximum CO2 emissions - I don't think those are sustainable approaches.

RAMIREZ-FRANCO: The way he and other researchers see it, we just haven't been producing concrete in the smartest way, based on a climate change point of view. But that could soon change.

For NPR News, I'm Juanpablo Ramirez-Franco in DeKalb.

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