A revolutionary new approach, inspired by the natural processes of coral reefs, promises to capture carbon dioxide from the atmosphere and transform it into durable, fire-resistant building materials. Developed by researchers at the University of Southern California (USC), this method provides a promising solution for carbon-negative construction and is detailed in a recent study published in npj Advanced Manufacturing. By mimicking coral’s ability to create robust structures while sequestering carbon, the new approach results in mineral-polymer composites with extraordinary mechanical strength, fracture toughness, and fire resistance.

The idea behind this breakthrough stems from the natural world, particularly the way coral reefs sequester carbon dioxide and form solid, resilient structures. Coral reefs naturally capture carbon dioxide from the atmosphere through photosynthesis, converting it into aragonite, a type of calcium carbonate, which builds the reef’s hard skeletons. This biological process, known as biomineralization, was the key inspiration behind the USC team’s innovation.

While traditional carbon capture methods focus on storing carbon dioxide or turning it into liquid substances—often costly and inefficient—the USC approach integrates carbon capture directly into the creation of building materials, offering a much more cost-effective solution.

The research team, led by Qiming Wang, associate professor of civil and environmental engineering at the USC Viterbi School of Engineering, developed an innovative electrochemical manufacturing process that converts carbon dioxide into calcium carbonate minerals within 3D-printed polymer scaffolds. This process is inspired by coral’s ability to sequester carbon and build complex structures.

Wang explained, “Unlike traditional carbon capture technologies that focus on storing carbon dioxide or converting it into liquid, we have created a method that converts carbon into durable materials that can be directly used in construction.”

The team replicated coral’s natural process by creating 3D-printed polymer scaffolds designed to mimic coral’s organic templates, called corallites. These scaffolds were coated with a thin, conductive layer and connected to electrochemical circuits as cathodes. When immersed in a calcium chloride solution, the system was exposed to carbon dioxide, which underwent hydrolysis and broke down into bicarbonate ions.

These bicarbonate ions then reacted with calcium ions in the solution to form calcium carbonate, which filled the pores of the 3D-printed structures. The result was a mineral-polymer composite that not only retained exceptional mechanical strength but also exhibited remarkable fire-resistant properties.

One of the most surprising discoveries during the research was the fire-resistant capabilities of the mineralized composite. While the polymer scaffolds used in the process are not inherently fire-resistant, the mineralized composites showed incredible resilience when subjected to direct flame tests. The composite material maintained its structural integrity under 30 minutes of direct flame exposure.

Wang noted, “The calcium carbonate minerals in the composite release small amounts of carbon dioxide when exposed to high temperatures. This appears to have a fire-quenching effect, acting as a natural fire suppression mechanism.”

This unique feature provides significant advantages for construction and engineering, where fire resistance is a critical concern. The incorporation of fire-resistant properties within the building material itself could make it safer and more durable for a variety of applications.

In addition to its fire resistance, the mineral-polymer composite offers a self-repairing capability. When cracks occur in the material, they can be restored by applying low-voltage electricity. The electrochemical reactions can rejoin the cracked interfaces, effectively repairing the structure and restoring its mechanical strength.

Moreover, after conducting a life cycle assessment, the researchers found that the composite materials have a negative carbon footprint. The carbon captured during the process exceeds the carbon emissions associated with their manufacturing, meaning these materials contribute to reducing atmospheric carbon rather than increasing it.

The potential applications of this carbon-negative material extend far beyond simple carbon capture. The research team demonstrated how the composites could be assembled into larger structures using a modular approach, paving the way for large-scale, load-bearing construction materials. These composites could be used in a wide range of construction applications, from residential buildings to infrastructure requiring high mechanical resistance.

Wang and his team are now focused on commercializing the patented technology. With construction and building materials accounting for around 11% of global carbon emissions, this new approach could lay the foundation for the creation of carbon-negative buildings—a crucial step toward mitigating the effects of climate change.

“The possibility of carbon-negative buildings is within our reach,” Wang said. “By transforming carbon dioxide into materials that can be used in construction, we’re not just reducing emissions, we’re also creating a pathway to more sustainable and fire-resistant buildings.”

This breakthrough demonstrates how nature’s design principles—such as those found in coral reefs—can inspire innovative solutions to some of today’s most pressing environmental challenges, making a tangible impact on carbon capture, sustainability, and construction.

By Impact Lab