New research shows that 3D-printed cement paste used in the process of building concrete structures actually gets stronger as it ages. Scientists believe this discovery could be used to build much stronger concrete structures that could withstand earthquakes and tornadoes.
Jan Olek, professor at Purdue’s Lyles School of Civil Engineering, commented, “Nature has to deal with weaknesses to survive, so we are using the ‘built-in’ weaknesses of cement-based materials to increase their toughness.”
Scientists Find Interesting Designs in Nature
These researchers are experimenting with designs that have been inspired by arthropod shells that control the way the damage develops. The mantis shrimp conquers its prey using a ‘dactyl club’ appendage that grows stronger as it is twisted.
Pablo Zavattieri, professor of civil engineering, explains, “The exoskeletons of arthropods have crack propagation and toughening mechanisms that we can reproduce in 3D-printed cement paste.”
He went on to explain how 3D-printed cement-based materials like concrete, mortar, and cement paste could give engineers excellent control over more than just the design of the structure. They could influence the structure’s performance as well.
A group of Purdue engineers has been experimenting with 3D printing for some time. They believe that they can achieve unique properties using special molds made for the 3D print process.
Purdue professor of materials engineering, Jeffrey Youngblood, adds, “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.”
Using the Weaknesses in Building Materials
The team of scientists began by studying micro-CT scans to help them understand how hardened 3D-printed cement-based materials would crack under pressure. Next, they used these so-called “weak characteristics” to build strength into the finished product.
Their findings were presented at the very first International Conference on Concrete and Digital Fabrication. This organization works to develop 3D printing techniques that make it easy and cost-efficient to build structures in areas where traditional construction is hampered by various factors. Some entrepreneurs have suggested that small 3D printed houses could be built for the homeless. Other applications include building these houses in areas that have just been devastated by a natural disaster.
A traditional house might take months to complete, but a 3D printed house can be completed in days, making it perfect to be used as temporary housing or as housing for the poor.
Various types of architectural techniques have experimented with the behaviors of a 3D-printed element once it has hardened. Some have shown to produce a spring-like behavior in the cement-based components, even though they’re made of brittle material.
This work was funded by a grant from the National Science Foundation and has been highly successful, not to mention completely unique. Scientists are continuing to develop new techniques and types of architecture that will complement the 3D printing process for building cement structures.