Can cement be greener? Industry seeking ways to lower carbon dioxide emissions

With construction season in full swing, the price we pay for our bridges and roads doesn’t just amount to dollars and time spent in traffic.

One core material releases an extreme amount of carbon dioxide each year, representing a whopping 7% to 8% of global emissions: concrete, or more specifically, cement.

Concrete — one of the world’s most consumed materials second only to water, according to MIT’s Climate Portal — is a mix of water, sand and gravel. Cement is the magic glue that binds all the ingredients together and gives concrete its prized durability.

But creating cement leads to the release of an enormous amount of CO2. For instance, cement’s 7-8% of global emissions easily beats out the global aviation industry, which sits at 2%. In fact, if the cement industry were a country, it would rank as the world’s fourth largest greenhouse gas emitter, just behind China, the U.S. and India, according to the Natural Resources Defense Council.

Cement production creates carbon dioxide in two ways: first, through the chemical reaction that occurs as crushed minerals are heated in a kiln and second, through heating the kiln to extremely high temperatures, which typically must be done using fossil fuels.

Given cement’s essential role in countless global construction projects, including projects closer to home such as the ongoing redo of the Kennedy Expressway, researchers have been searching for ways to lower the emissions of cement production and change concrete’s ingredients.

One team of researchers at the University of Illinois Urbana-Champaign, alongside the Meta Sustainability Net Zero program and concrete supplier Ozinga, are looking to discover better concrete formulas using artificial intelligence.

Early-stage results found the AI-powered formulas reduced the carbon footprint of the concrete by 40% while maintaining the material’s critical strength and durability. Meta even tested the formulas on multiple structures at the company’s DeKalb data center, namely the floor slabs of the guardhouse and construction management team’s temporary offices.

“One thing for sure is that as we move forward into the realm of these newer cements, the mix designs of concrete will get even more and more complicated, because you have so many ingredients, and all of these ingredients have different properties,” said Nishant Garg, an assistant professor of civil and environmental engineering at the University of Illinois who specializes in the chemistry and characterization of construction materials.

Garg added the process is made even more complex because researchers are looking to optimize performance, cost and sustainability.

“That's where we're exploring the use of this AI-based approach where we have an AI model trained on a large number of mixes and of different properties to see if we can generate recipes, which could meet all the criteria for any given user,” he said. “I think in the future that approach will become more and more common.”

Research on more sustainable cement has been ongoing for decades, though Garg said the momentum behind that research has sped up exponentially over time, especially as climate change has gained more of the spotlight.

The result is several viable solutions that have been developed and tested at the lab scale. The next step is market adoption, which Garg said will take large-scale investments from producers, open minds from consumers and a little help from the government.

“It is possible to have a concrete which does not only have good performance, but also is sustainable. We don't have to sacrifice one for the other — we can have them all. Those solutions exist in the lab, but people just need to be a little bit open-minded and take some risks to start producing them,” he said. “Traditionally, the construction industry has been very conservative. They don't want to try new things. This is where the government has a very, very important role to play.”

That’s because it’s likely inevitable that sustainable alternatives will be more expensive than traditional concrete when they first hit the market. Garg compared the new mixes to electric vehicles, in that there will be a limited supply followed by more momentum in the market, which can be helped along by government incentives.

“The government can provide these levers,” he said. “They can provide incentives for both consumers and producers to help the market get going, and once it gets there, the government can withdraw its hand and things will take off. But initially, we need that help.”

• 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.