Using nature as inspiration to solve a problem is called biomimicry. The idea spawned from the premise that animals, plants and microbes have for billions of years been solving problems that humans are still trying to figure out. While the idea of biomimicry is centuries old - Leonardo da Vinci looked to birds when designing flying machines in the 15th century - the term was only popularized within the last 20 years or so.

Researchers at the German University of Konstanz recently applied biomimicry to create stronger cement, taking inspiration from the spines of sea urchins, which are made primarily of calcite. Though calcite is normally brittle, sea urchin spines are strong.

On a molecular level, the sea urchin spine is built like a brick wall: as bricks are surrounded by mortar, the calcite is cushioned by a softer, amorphous material. When fractures occur in the calcite, the energy is transferred to the cushion, preventing damage from spreading.

Applying this concept to cement, the scientists structured their new product so that the calcium silicate hydrate (the binding agent of concrete) is cushioned by a polymeric binder that can absorb energy from fractures. They report that a pillar made of this cement could be built nearly 5 miles high before collapsing - ten times as tall as the Burj Khalifa, which measures up at just over half a mile.

Testing the new cement for fracture resistance in collaboration with the University of Stuttgart, researchers found that the new product withstood 200 megapascals of pressure, the equivalent of 29,000 psi. They report that the concrete commonly used around the world ranks in at no higher than 5 megapascals, or 725 psi.

The full study is available at https://tinyurl.com/y8rvc5qq.