Cement paste is known to be an important constituent of concrete and mortar, used in building numerous elements of an infrastructure. It gets tougher under mechanical loads or high pressure, similar to the shells of arthropods such as beetles and lobsters. Researchers from Purdue University have recently 3D printed cement paste which is believed to contribute to more resilient structures at the time of natural calamities such as earthquakes.
According to Jan Olek, a professor in Purdue, they are using the inherent weakness of cement-based material to increase their toughness. The idea is to generate unique damage mechanism by using bio-inspired designs to control how destruction widens between the printed layers of a material.
Pablo Zavattieri, a civil engineering professor in Purdue said, the external skeleton of arthropods have damage propagation and toughening mechanisms that can be reproduced in the 3D printed cement paste. According to the researchers, 3-D printed cement-based materials including paste, mortar, and concrete will enable engineers to have more control over design and performance, but there are certain technicalities that pose as a challenge to their adoption.
“3-D printing removes the need to create mold for each design and hence can achieve the critical properties of cement materials that were not possible before”, said a Purdue professor of materials engineering.
The researchers used micro CT scans to better understand the properties of hardened 3D printed cement paste as well as to reap the benefits of their weakness, for example, pore regions found at interfaces between the printed layers of cement can promote cracking. With 3-D printing cement-based materials, there is more control over the structure, resulting into the creation of more damage-tolerant infrastructural elements, said Mohamadreza “Reza” Moini, a civil engineering Ph.D. candidate in Purdue.
The team developed and designed several bio-inspired cement paste elements by using 3-D printing techniques which behave like a spring. Some of the designs include, ‘honeycomb’, ‘Bouligand’, and ‘complaint which are called ‘architectures’. Initially, it was inspired by dactyl club appendage of mantis shrimp which is used to capture its prey. Through twisting cracks, the shell gets tougher that dissolves energy and prevent the club from falling apart.
The research team aims to discover more ways in which cement-based materials could be designed to create more resilient infrastructure.