Fracture-resistant cement inspired by the spines of sea urchins

The natural world is a constant source of inspiration for scientists and engineers. The latest biologically influenced innovation comes from a team of German researchers who developed a new type of stronger cement inspired by nanostructures found in sea urchin spines. The team was inspired by the structural resilience of sea urchin spines, which are primarily made up of a brittle material called calcite. Yet despite the nature of calcite, the spines are incredibly durable because of a nano-level, brick-and-mortar style architecture. It was discovered that sea urchin spines are so tough because the crystalline blocks of calcite are surrounded by softer areas of a material called calcium carbonate. This means that when the calcite cracks, the energy moves to the softer layer preventing any further cracking. The challenge when translating this principle to cement was that cement is a much more disordered structure. Helmut Cölfen, head of the research team, says the team had to find a way to generate “fracture-resistance at the nano-level.” The key was discovering a material that only adhered to the cement particles allowing for this brick-and-mortar effect to be replicated within the cement on a nano-scale. Ten negatively charged peptide combinations were identified as perfect molecules to create the nanostructured cement. Using an electron microscope to analyse and test the resulting optimised cement the team calculated it to have a fracture resistance value of 200 megapascals, which is approaching the value of steel. The study concludes that this new cement could create concrete that is between 40 and 100 times stronger than current mixes. “Our cement, which is significantly more fracture-resistant than anything that has been developed thus far, provides us with completely new construction possibilities”, says Cölfen. The results were published in the journal Materials Science.

New Atlas, 1 December 2017 ;