A research team based out of Purdue University’s Lyles School of Civil Engineering have developed a 3D printed flexible cement that only gets stronger when pressure is applied. Among the team members are professors Jan Olek, Pablo Zavattieri, Jeffrey Youngblood, and Ph.D. candidate Mohamadreza Moini.
The 3D printed flexible cement project first initiated back in August of 2016 with funding from The National Science Foundation. A team of researchers cycled through several different geometric configurations before deciding on the final design. They experimented with honeycomb, auxetic, and bouligand designs each one responding differently than the last. Some designs acted as a spring when put under stress while others boosted crack resistance.
“The exoskeletons of arthropods have crack propagation and toughening mechanisms,” said Pablo Zavattieri, “both of which can be reproduced in 3D printed cement paste.”
The Purdue team used micro-CT scanners to test the structural qualities of each prototype. By using this tool the team could easily identify any weaknesses that presented themselves within the 3D printed objects and could then improve with the next prototype.
“3D printing cement-based materials provides control over their structure, which can lead to the creation of more damage and flaw-tolerant structural elements like beams or columns,” said Mohamadrez “Reza” Moini, a Purdue Ph.D. candidate of civil engineering.
Purdue engineers are the first ever to use 3D printing when creating different bio inspired structures out of cement paste. The team’s design was initially inspired by the mantis shrimp, which hunts using a “dactyl club” like appendage that becomes stronger on impact through twisting and cracking that helps dissipate the energy and prevent the shrimps club from falling apart.
“3D printing has removed the need for creating a mold for each type of design, so that we can achieve these unique properties of cement-based materials that were not possible before,” said Jeffrey Youngblood, a Purdue professor of materials engineering.