Purdue University researchers have drawn inspiration from arthropod shells to 3D print a tougher version of cement paste.
“Nature has to deal with weaknesses to survive, so we are using the ‘built-in’ weaknesses of cement-based materials to increase their toughness,” said professor Jan Olek from Purdue’s Lyles School of Civil Engineering.
Arthropods like lobsters and beetles possess shells that get tougher under pressure. The researchers believe that their cement paste could lead to more resilient structures during natural disasters.
The arthropod shell designs are helping the researchers to control how damage spreads between the printed layers of a material.
“The exoskeletons of arthropods have crack propagation and toughening mechanisms that we can reproduce in 3D printed cement paste,” said Pablo Zavattieri, Purdue professor of civil engineering.
The team is using micro-CT scans to better understand the behavior of hardened 3D printed cement-based materials and take advantage of their weak characteristics.
These include pore regions found at the ‘interfaces’ between the printed layers, which promote cracking.
According to Purdue Ph.D. candidate Mohamadreza Moini, 3D printing offers better control over cement material structures, paving the way for more damage and flaw-tolerant structural elements like beams or columns.
The team was initially inspired by the mantis shrimp, which conquers its prey with a ‘dactyl club’ appendage that grows tougher on impact through twisting cracks that dissipate energy and prevent the club from falling apart.
Some of the bioinspired cement paste elements designed and fabricated by the team include the honeycomb, compliant and Bouligand designs called ‘architectures.’
Each of these architectures allowed for new behaviors in a 3D-printed element once hardened.
According to the researchers, the Bouligand architecture took advantage of weak interfaces to make a material more crack-resistant.
The compliant architecture on the other hand makes cement-based elements act like a spring, even though they are made of brittle material.
Purdue University Concrete 3D Printing Team/Mohamadreza Moin