Concrete helped build the modern world, and drove it towards the climate crisis. Now, it might help undo the damage.
Long seen as the backbone of civilisation, concrete is responsible for nearly 9% of global greenhouse gas emissions. Its primary ingredient, cement, releases massive amounts of CO₂ during production, making it one of the most polluting materials on Earth.
But a team of engineers, designers, and materials scientists at the University of Pennsylvania may have cracked a cleaner future.
The remarkably lightweight, yet structurally sound concrete captures 142% more CO₂ than conventional mixes. Image: University of Pennsylvania.
By blending 3D printing with fossilised algae and rethinking concrete’s internal geometry, they have created a lightweight, low-cement mix that not only holds its strength but absorbs up to 142% more carbon dioxide than traditional formulations.
Shape, strength, and sustainability
The key lies in diatomaceous earth, a powdery substance made from the ancient silica shells of microscopic algae. Paired with a mathematical design inspired by coral and sea stars, this bio-mineral concrete captures more carbon, uses less material, and could one day double as a tool for restoring marine ecosystems.
Yang had previously studied diatoms in the context of ocean carbon sinks and saw potential in bringing their natural CO₂-trapping abilities to construction materials.
“Usually, if you increase the surface area or porosity, you lose strength,” says Shu Yang, co-senior author of the study. “But here, it was the opposite; the structure became stronger over time.”
The solution is based on diatomaceous earth and offers enhanced carbon capture and structural fortitude while using relatively fewer materials. Image: University of Pennsylvania.
Yang explained that the team achieved a 30% boost in CO₂ absorption by fine-tuning the material’s internal geometry without compromising structural integrity.
However, the breakthrough depends not just on the material itself, but also on its geometry.
Co-senior author Masoud Akbarzadeh and his team drew inspiration from triply periodic minimal surfaces (TPMS), naturally efficient structures found in coral reefs, bones, and sea stars.
These smooth, continuous forms are prized for their ability to maximise surface area and stiffness while using minimal material, making them well suited for both structural strength and carbon absorption.
Using a technique called polyhedral graphic statics, the researchers mapped out how forces move through these geometries and designed forms that remained stable under compression, even with steep overhangs and large voids.
Post-tensioning cables were added to enhance internal strength, allowing the concrete to stay lightweight without sacrificing durability.
Once the structure was modelled, it was digitally sliced into printable layers and fed into a 3D printer using a specially developed concrete ink.
Less mass, more impact
Despite its high porosity, the printed material grew stronger as it absorbed carbon dioxide during curing.
Lab tests showed it retained 90% of the strength of solid concrete blocks, while using 68% less material and achieving 32% higher CO₂ uptake per unit of cement.
Now, the team is scaling up the technology for larger architectural components such as facades, panels, and even marine infrastructure.
“We’re testing larger components with more complex reinforcement schemes,” says Akbarzadeh, referring to the embedded post-tensioning cables and force-balancing geometries that his lab specialises in. “We want these to be not just strong and efficient, but buildable at architectural scale.”
The key ingredient is diatomaceous earth (DE), a popular filler material made from fossilised microorganisms. Image: University of Pennsylvania.
Thanks to its porosity and compatibility with aquatic life, the concrete could be used in coral restoration projects or artificial reefs, offering both structural support and environmental benefit.
Yang’s team is also investigating how diatomaceous earth might interact with alternative binder chemistries, including magnesium-based and alkali-activated systems, in a bid to move beyond conventional cement.
“The moment we stopped thinking about concrete as static and started treating it as dynamic – something that interacts with its surroundings – we unlocked entirely new possibilities,” says Yang.
The findings have been published in the journal Advanced Functional Materials.