Bone-like, hollow concrete design makes it 5.6 times stronger

Their solution is derived from a human femur’s dense outer shell, known as the cortical bone. In this vital layer, numerous elliptical, tubelike parts called osteons are suspended in an organic matrix, which are then surrounded by comparatively weak interfaces, coincidentally also called “cement lines.”
Whenever stress is applied to the bone, these cement lines provide a “microstructurally preferable crack path,” the study authors write, “hence triggering in-plane crack deflection around osteons due to cement line-crack interaction.”

“One expects the material to become less resistant to cracking when hollow tubes are incorporated,” Reza Moini, an assistant professor of civil and environmental engineering and study lead, said in Monday’s announcement. “We learned that by taking advantage of the tube geometry, size, shape, and orientation, we can promote crack-tube interaction to enhance one property without sacrificing another.”
Using these properties, engineers adapted concrete production models and tested if bioinspired, similarly hollow shapes boosted their strength. Unlike other concrete variants, however, the new materials didn’t require additives like fibers or plastics. Instead, they simply relied on precise geometric designs.