Cement 5 times stronger than traditional cement and inspired by human bone is created
Engineers have developed a cement-based material that is 5.6 times more resistant to damage than conventional cements. And it was inspired by human cortical bone.
Inspired by the architecture of the hard outer layer of human bone, engineers at Princeton University have developed a cement-based material that is 5.6 times more resistant to damage than traditional cements.
The bioinspired design allows the material to resist cracking and prevent sudden failure. This sets it apart from its conventional, brittle cement-based counterparts.
In a paper published in the journal Advanced Materials, the research team led by Reza Moini and Shashank Gupta demonstrates that cement paste implanted with a tube-shaped architecture can significantly increase resistance to crack propagation and improve the ability to deform without sudden failure.
Cement inspired by human cortical bone
In brittle construction materials used in buildings and civil infrastructure, strength ensures the ability to withstand loads, while toughness promotes resistance to cracking and damage propagation in the structure. The proposed technique solves these problems by creating a material that is stronger than conventional materials without losing its strength.
According to Moini, the key to the improvement lies in the intentional design of the internal architecture, balancing the stresses at the crack front with the overall mechanical response. “We used theoretical principles of fracture mechanics and statistical mechanics to improve the fundamental properties of the materials ‘by design’,” he explains.
The team took inspiration from human cortical bone, the dense outer layer of human femurs that provides strength and resists fracture. Cortical bone is composed of elliptical tubular components known as osteons, loosely embedded in an organic matrix. This unique architecture deflects cracks around the osteons. This prevents abrupt failure and increases the overall resistance to crack propagation, explains Gupta.
Stepwise toughening mechanism
The bioinspired design incorporates cylindrical and elliptical tubes within the cement paste that interact to promote crack propagation. “The material is expected to be less resistant to cracking when hollow tubes are incorporated,” said Moini. “We learned that by leveraging the geometry, size, shape and orientation of the tube, we can promote the tube-crack interaction to improve one property without sacrificing another,” he added.
The team found that this enhanced crack-tube interaction initiates a stepwise toughening mechanism, in which the crack is first trapped by the tube and then its propagation is delayed, causing additional energy dissipation with each interaction and step.
“What makes this stepwise mechanism unique is that each crack extension is controlled, preventing sudden and catastrophic failure,” explains Gupta. “Instead of suddenly breaking, the material resists progressive damage, making it much stronger,” he said.
Method for quantifying degree of disorder in materials
In addition to improving fracture toughness, the researchers introduced a new method for quantifying the degree of disorder, an important magnitude for design. Drawing on statistical mechanics, the team introduced parameters to quantify the degree of disorder in architectural materials. This allowed the researchers to create a numerical framework that reflects the degree of disorder in architecture.
They say the new framework provides a more accurate representation of material arrangements, moving toward a spectrum from ordered to random, beyond simple binary classifications of periodic and non-periodic. Moini noted that the study distinguishes approaches that confuse irregularity and disturbance with statistical disorder, such as Voronoi tiling and perturbation methods.
“This approach gives us a powerful tool for describing and designing materials with a tailored degree of disorder,” Moini says. “The use of advanced manufacturing methods, such as additive manufacturing, can further facilitate the design of more disordered and mechanically favorable structures and allow the scaling of these tubular designs for concrete civil infrastructure components,” he commented.
News reference:
Gupta, S.; Moini, R. Tough Cortical Bone-Inspired Tubular Architected Cement-Based Material with Disorder. Advanced Materials, 2024.
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