Cement is the foundation of our civilization — quite literally. We couldn’t construct the buildings around us without cement. We couldn’t have durable constructions. Everything would fall apart. But the cement industry is one of the two largest producers of carbon dioxide (CO2), creating up to 5% of worldwide man-made emissions. If cement production were a country, it would only be overtaken by China, the US, and India.
But we can do better.
Researchers are constantly looking at ways to make cement more durable and more sustainable. In a recent study, they took inspiration from an unlikely source: seashells.
Hard and Soft
At the center of this innovation is a material found in seashells. Known as nacre, or “mother of pearl”, this shimmering substance has long fascinated scientists for its uncanny ability to resist shattering.
Nacre is built from microscopic tablets of aragonite, a brittle mineral, bonded with a pliable organic glue. Under pressure, these tablets slide against one another. That sliding spreads out the force, diffusing energy that might otherwise shatter the shell. Simply put, nacre is very efficient at stopping cracks from propagating.
“If we can engineer concrete to resist crack propagation, we can make it tougher, safer and more durable,” said researcher Shashank Gupta, a graduate student in Reza Moini’s lab in the Department of Civil and Environmental Engineering.
The key element seems to be the synergy between the hard aragonite crystals and the soft glue. To recreate that, the researchers created thin sheets of cement paste, then used a laser to engrave hexagonal grooves into them — patterns similar to nacre’s aragonite tablets. These grooves weren’t just cosmetic. In some cases, they completely separated the sheets into individual cement “tablets.”
These were layered with a soft, rubber-like polymer that mimicked nacre’s organic glue. It bonded the cement tablets but also allowed them to move — just enough to spread out stress when the material was bent or cracked.
From Brittle to Bendable
“Our bio-inspired approach is not to simply mimic nature’s microstructure but to learn from the underlying principles,” said Moini. “We intentionally engineer defects in the brittle materials as a way to make them stronger by design.”
The results were striking. When tested in the lab, the nacre-like composites didn’t crack the way ordinary cement does. Standard cement beams failed suddenly, with one large fracture splitting the material. In contrast, the nacre-inspired beams showed a slow spread of small cracks. Essentially, they bent more before breaking. They resisted crack growth.
The researchers tested three versions of the composite. The one with fully separated hexagonal tablets — most similar to actual nacre — performed best. It held 19 times more strain before breaking and had a fracture toughness 17 times greater than the reference cement paste.
This kind of improvement is rare. Most attempts to toughen cement — by adding fibers or changing its chemistry — yield only modest gains. What makes this work remarkable is that the underlying material, Portland cement, remains largely unchanged. So, it’s the structure that makes the difference.
This could be a game changer. Cement and concrete are inherently brittle. They don’t deform much before snapping. That makes them vulnerable under impact, seismic activity, or long-term stress. What Moini’s team has done is uncover a new way to fight that brittleness — not by swapping out ingredients, but by rearranging them with intention.
An Innovation with Promise
For now, the work is confined to the lab. The beams tested were small — centimeters in size. Scaling up will raise new questions. Will the polymer degrade over time? Can the material withstand weather, moisture, freezing? There’s also the matter of cost; if it’s too expensive, it could simply be cheaper to replace the concrete over time.
Still, the promise is compelling. With more research, these nacre-like composites could be adapted, at least for high-risk applications — like earthquake-resistant buildings or impact-resistant infrastructure. Plus, there could be much more innovation in the natural world just waiting to be discovered.
“We are only scratching the surface; there will be numerous design possibilities to explore and engineer the constitutive hard and soft material properties, the interfaces, and the geometric aspects that play into the fundamental size effects in construction materials,” Moini concludes.
Journal Reference: Shashank Gupta et al, Tough and Ductile Architected Nacre‐Like Cementitious Composites, Advanced Functional Materials (2024). DOI: 10.1002/adfm.202313516
