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The brittle nature of masonry walls causes them to fracture easily under extreme loads by vehicular crashes, blasts, gas explosions, earthquakes, resulting in huge damage to the infrastructure.
However, this problem can be minimized by embedding auxetic materials in the mortar, which increases the energy absorption capacity of the walls.
Auxetic materials have the ability to expand or contract in all directions at once instead of bulging or flattening on the application of force, making them highly energy absorbent and load resistant.
Inspired by the material used in running shoes and memory foam pillows, Dr. Tatheer Zahra, a researcher from QUT Centre of Materials Science and QUT School of Civil and Environmental Engineering, claims to have used off-the-shelf bioplastic to 3D print geometric shapes that mimic the behavior of auxetic materials.
The newly designed geometric shapes exhibit all the properties of auxetic materials. Made from bioplastic, these are biodegradable, have low carbon emissions, are readily available, and cost less than the commercially used auxetic materials.
These 3D printing auxetic geometries have the energy absorption capacity equivalent to a 20 mm thick reinforced composite protective render over a full-scale building wall, which could withstand the impact force of a car traveling at 60 km/hr.
The auxetic geometries could offer a better replacement for steel and fiber-reinforced polymer in the near future and can be used as a protective wall render.
Auxetic geometries can also protect the structures from microorganisms and high temperatures of up to 60° Celsius, thereby increasing the life of the buildings.
After successful testing at the lab, Dr. Zahra now aims to test the designs on full-scale masonry and concrete structures at the QUT Banyo Pilot Plant.
With the easy availability of bioplastic and hassle-free production processes, the geometric designs render good prospects for commercial use.
3D printing further enables the customization of size, material, or design of geometric shapes to suit different structures and load requirements. The development can be seen as a big step towards achieving sustainability in the construction industry.