UW-led team developing new ‘carbon-negative’ form of cement

A team led by UW-Madison engineers is developing a new form of cement in hopes of lowering the environmental impact. 

According to an overview from the university’s College of Engineering, production of the most frequently used cement in the world — called portland cement — leads to 3 billion tons of carbon dioxide being released into the atmosphere annually. That accounts for about 8 percent of all emissions coming from human activities, the university says. 

By using a direct-capture carbon removal system previously developed by UW-Madison professors and combining the resulting materials with industrial waste products, the research team aims to create a form of carbon-negative cement to replace portland cement. 

Rob Annex, a professor of biological systems engineering, and Bu Wang, an assistant professor of civil and environmental engineering, created the direct-capture system for the Musk Foundation’s 2022 XPRIZE carbon removal competition. The system draws carbon dioxide out of the air and ultimately creates a material that can be combined with coal ash to create constituent elements of cement. 

“Portland cement today is produced using raw materials like limestone, clay and sand,” Wang said in the university’s overview. “In our new cement, one of the key ingredients is waste materials — like coal ash, slag from steel and iron production, or cement kiln dust.”

The overview shows prior efforts to make concrete that captures carbon from the atmosphere have resulted in mixtures that captured little carbon and “haven’t been suitable for casting and setting on-site.” According to Wang, the new mixture may offer a way to put carbon dioxide into the material before it’s made. 

“When we make the concrete, the carbon dioxide is already there, so all we’d have to do is pour it like normal and allow it to harden by itself,” he said. 

Wang and Annex are working on this effort with other researchers at Pennsylvania State University and the University of Illinois-Chicago. It’s one of 18 such projects funded through a U.S. Department of Energy initiative, getting $2.3 million in grant funding over three years. 

Find more details here: https://engineering.wisc.edu/news/building-on-a-solid-process-wang-pours-resources-into-making-carbon-negative-cement/