Researchers at Northwestern University have developed a new method to convert carbon dioxide (CO₂) into a solid mineral that can be used in cement and concrete applications. The material is produced using seawater, electricity, and CO₂, offering a carbon-negative alternative to traditional cement components.

Mineralisation process and composition
The process creates calcium carbonate, the primary component of limestone, by electrochemically removing carbon dioxide from water and converting it into solid form. The approach does not require rare-earth elements or high-pressure environments, and is designed to operate under ambient conditions.

The resulting material consists of carbon-negative calcium-based solids, including stable carbonates and brucite, which can serve as a binder or aggregate in concrete formulations. The method builds upon natural mineralisation processes, and can be carried out near point-source CO₂ emissions.

Application in construction materials
According to laboratory tests, the material can be used as a cement replacement or additive in concrete mixtures without loss of mechanical strength. The mineral exhibits durability and structural integrity comparable to conventional cement-based products. This may allow for partial or full replacement of Portland cement, which is a major contributor to global greenhouse gas emissions.

The technique has potential relevance for architects, interior and landscape designers, and product developers working with concrete or cementitious components in built environments. It offers a way to reduce the embodied carbon of structures, pavements, tiles, and related architectural or infrastructural elements.

Resource use and scalability
The process uses seawater as a mineral source and does not rely on mined limestone or other finite mineral resources. The research team suggests the method could be scaled for industrial use by installing the technology near CO₂-emitting facilities, such as cement plants or power stations. The mineralised CO₂ remains chemically stable, reducing the risk of re-release into the atmosphere.

Potential for design integration
Besides use in cementitious materials, the researchers note that the physical characteristics of the carbonated solids—such as tunable porosity, strength and particle shape—may enable broader material applications in construction or product design. These could include use in cast elements, surface panels, or modular components, particularly where low-carbon or carbon-storing materials are required.

The findings were published in Advanced Sustainable Systems and supported by the US Department of Energy and the Institute for Sustainability and Energy at Northwestern.

Source: Northwestern Now
Image: Northwestern University