Researchers at the University of California Los Angeles (UCLA), in a project managed by NETL, developed and demonstrated a new approach for making ordinary Portland cement replacement in concrete that can significantly reduce carbon dioxide (CO₂) emissions and is already being commercialized for use in U.S. cement plants.

The global market for concrete is around $1 trillion. Almost all concrete contains Portland cement, a limestone and clay fusion that’s cheap and abundant, but involves a carbon-intensive process. According to UCLA, traditional cement production accounts for nearly 10% of global CO₂ emissions because 0.9 tons of CO₂ are emitted per ton of cement produced and 4.5 billion tons of cement are produced annually.

When mixed with water, cement acts as the glue that binds the coarse and fine aggregate particles together to create concrete. Cement is the world’s most common building material and is used in bridges, roads, buildings, dams, powerplants and wind-turbine foundations.

The U.S. Department of Energy Office of Fossil Energy and Carbon Management (FECM) recognized the unique opportunity of this project to both reduce the emissions of climate-warming CO₂ as well as convert and store captured CO₂ in large quantities. UCLA pursued a mineralization approach to reduce CO₂ emissions during the cement-making process and use CO₂ captured from various sources — a win-win solution for the concrete industry and efforts to reduce CO₂ in the atmosphere.

According to the World Resources Institute, mineralization “accelerates reactions between CO₂ and certain minerals, removing CO₂ from the atmosphere and permanently storing it. Although this process occurs naturally over hundreds or thousands of years, carbon mineralization can be sped up in numerous ways to remove large amounts of atmospheric CO₂ in the coming decades.”

The new process uses calcium hydroxide (Ca(OH)₂)for mineralization in the cement-making process and reduces the use of Portland cement in concrete production. Ca(OH)₂ is a colorless crystal or white powder and is produced when calcium oxide is mixed with water. It can be produced thermally and electrochemically without CO₂ emissions.

NETL Project Manager Kanchan Mondal said, “the UCLA project demonstrated that CO₂ mineralization is a simple, straightforward, and ready to deploy pathway for reducing CO₂ in concrete production.”

Mondal added that the UCLA team demonstrated the feasibility of the technology at pilot-scale and exceeded project milestones advancing its technology readiness for commercialization.

“The technology is already being commercialized at concrete masonry plants,” Mondal said.

FECM conducts research, development, demonstration, and deployment to minimize the environmental and climate impacts of fossil fuel and industrial processes while working to achieve net-zero emissions across the U.S. economy. Priority areas of technology work include carbon capture, carbon conversion, carbon dioxide removal, carbon dioxide transport and storage, hydrogen production with carbon management, methane emissions reduction, and critical minerals production. 

NETL is a U.S. Department of Energy national laboratory that drives innovation and delivers solutions for a clean and secure energy future. By using its highly skilled innovators and state-of-the-art research facilities, NETL is advancing carbon management and resource sustainability technologies to enable environmental sustainability for all Americans.