Researchers at the University of Pennsylvania have developed a 3D printable concrete incorporating diatomaceous earth (DE), a fossil-based material derived from ancient microscopic algae. This mixture aims to improve structural performance and increase carbon dioxide (CO₂) uptake, addressing environmental concerns associated with conventional concrete.
From Algae to Architecture: A Smart Mix for CO₂ Capture
Concrete is widely used in infrastructure but contributes approximately 9% of global greenhouse gas emissions. To reduce this impact, the Penn team developed a concrete that absorbs up to 142% more CO₂ than standard mixes while reducing cement content.
DE’s porous, sponge-like structure improves flow behavior during 3D printing and provides sites for carbon dioxide to bind. It also facilitates calcium carbonate formation during curing, which enhance the material’s strength. This approach addresses the common trade-off between porosity and mechanical strength found in cement-based materials.
The researchers refined the concrete’s geometry using triply periodic minimal surfaces (TPMS)—organic forms inspired by structures like bones and coral—to maximize surface area and stiffness while minimizing material use. To ensure structural stability, co-senior author Masoud Akbarzadeh and his team employed polyhedral graphic statics. This enabled the design to remain self-supporting, even with overhangs, while maintaining internal voids critical for CO₂ exposure. For added reinforcement, post-tensioning cables were strategically integrated into the structure.
Testing showed the printed concrete used 68% less material, increased surface-area-to-volume ratio by over 500%, retained 90% of the compressive strength of solid forms, and absorbed 32% more CO₂ per unit of cement.
Scaling Toward Impact
The team is advancing from prototypes to full-scale architectural components—such as floors, walls, and facades—using reinforcement strategies rooted in the same geometric principles. Akbarzadeh emphasized that current efforts aim to ensure these elements are structurally viable at building scale.
Shu Yang, co-senior author and chair of Penn Engineering’s Department of Materials Science, noted that the material’s porosity and ecological compatibility make it also well-suited for marine restoration applications—such as artificial reefs and oyster habitats—where it could both support marine organism growth and absorb CO₂ from seawater.
Further research is exploring alternative binder chemistries, such as magnesium-based or alkali-activated systems, and the integration of industrial waste streams to replace conventional cement.
“We want to push this idea further. What if we could remove the cement altogether? Or use waste streams as the reactive component? The moment we stopped thinking about concrete as static and started seeing it as dynamic—as something that reacts to its environment—we opened up a whole new world of possibilities,” Yang added.
Sustainable Construction Through 3D Printing
In 2024, researchers from the Institute for Advanced Architecture of Catalonia (IAAC) 3D printed a 100 m2, low-carbon emissions building prototype using a Crane WASP 3D printer. This is the latest eco-friendly structure to be fabricated for the 3D Printed Earth Forest Campus (TOVA) in Collserola Natural Park (Barcelona). The IAAC team used local soil and natural materials as feedstock for the Postgraduate in 3D Printing Architecture (3DPA) project.
In the UK, Balfour Beatty and materials specialist Versarien are collaborating to develop low-carbon, graphene-infused 3D printable mortars for construction. Their partnership aims to enhance construction durability and efficiency while reducing environmental impact by establishing a local supply chain and introducing materials with improved resilience and cost-effectiveness. These materials are expected to be evaluated in real-world applications by Balfour Beatty’s Highways division, marking a shift towards more sustainable, high-performance alternatives in large-scale civil projects.
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Featured image shows 3D concrete printing system based on diatomaceous earth. Photo via University of Pennsylvania.
