‘Double twist’: Concrete crack resistance boosted 63% by fish scale design

Concrete is a ubiquitous building material, but over time, it may become prone to cracking. In order to ensure the long-term durability and safety of concrete structures, it is essential to prevent or minimize cracking.

Researchers have developed a novel approach to improve the longevity of concrete by increasing its fracture resistance mechanisms.

The Princeton Engineering team used cutting-edge additive manufacturing processes and precision robotic automation to create twisted concrete components. The resulting concrete is stronger and more durable than the standard cast concrete.

Interestingly, this new concrete has a 63% higher crack resistance than ordinary cast concrete.

Inspired by natural scales

Learning from nature’s architectural expertise, the researchers aimed to find similar principles to improve the crack resistance of concrete .

They drew inspiration from the double-helical scales of the coelacanth, an ancient fish lineage. These natural formations exhibit great strength and resistance to fracture.

The researchers then created a new concrete design based on the structure of coelacanth scales. A robotic printer produced a three-dimensional structure out of individual concrete strands.

One of the key design elements was the double-helical arrangement. This suggests that the strands were arranged in two layers that were twisted around each other, similar to a DNA molecule.

This pattern improved the material’s resilience to fractures. When a fracture begins to form, the twisted structure might help deflect or prevent it from spreading further.

“The paper refers to the underlying resistance in crack propagation as a ‘toughening mechanism.’ The technique relies on a combination of mechanisms that can either shield cracks from propagating,  interlock the fractured surfaces, or deflect cracks from a straight path once they are formed,” the authors explained in the press release.

New way to prevent deformation

Creating these intricate structures requires the precision and control of robotic fabrication. Researchers have been able to build sophisticated shapes that were previously difficult to achieve using standard casting processes — thanks to advancements in additive manufacturing.

The Princeton facility includes large-scale industrial robots outfitted with cutting-edge real-time material processing equipment. This enables researchers to create full-size structural components that are both functional and visually appealing.

Apart from this development, the team also created a new method to prevent fresh concrete from deforming throughout the 3D production process.

They used a “two-component extrusion system” that mixed concrete with a chemical accelerator just before printing. This helped to speed up the hardening process and prevent the concrete from sagging under its own weight.

“By precisely calibrating the amount of accelerator, the researchers gained better control over the structure and minimized deformation in the lower levels,” the press release noted.

This development has the potential to advance the construction industry and create safer, more durable structures in the future.

Meanwhile, research and development are actively going on to make environmentally friendly concrete. After the end of its use cycle, concrete often ends up in landfills, which poses significant environmental challenges.

Recently, researchers from the University of Tokyo have developed a novel approach to repurpose old concrete into sturdy building materials like blocks for houses and pavements.

The findings were published in the journal Nature Communications.