Researchers at Princeton University have developed a cement paste that is 5.6 times stronger than cement, mortar, and other conventional cement-based construction materials, reports Interesting Engineering. The paste features a tubular architecture inspired by the structure of human cortical bone, which forms the outer layer of the femur (thigh bone). “Cement paste deployed with a tube-like architecture can significantly increase resistance to crack propagation and improve the ability to deform without sudden failure,” according to the researchers. To decode the science behind crack-resistant cement, the researchers looked for materials that naturally possessed high strength and toughness. Soon they come across the human cortical bone, which resists fractures and provides the femur with the strength needed to support the body’s load. “Cortical bone consists of elliptical tubular components known as osteons, embedded weakly in an organic matrix. This unique architecture deflects cracks around osteons. This prevents abrupt failure and increases overall resistance to crack propagation," the researchers explained. Inspired by the tubular structure of cortical bone, the researchers developed a cement paste featuring cylindrical and elliptical tubes. These tubular structures improved the crack-resistant properties of the cement, similar to how osteons strengthen the femur. For instance, whenever a crack appears in a structure made with cement paste, it is trapped by the tubes, delaying its spread to other sections.