Researchers from Princeton Engineering have made advancements in crack resistance in concrete components by incorporating architected designs and additive manufacturing processes. In a study published in Nature Communications, the team led by Professor Reza Moini increased crack resistance by up to 63% compared to traditional cast concrete. Inspired by the double-helical structures found in the scales of coelacanth fish, the researchers designed concrete strands in three dimensions and used robotic additive manufacturing to connect them weakly. By stacking these strands into larger shapes like beams with a double-helical arrangement, they improved the material’s resistance to crack propagation.
The researchers described the resistance to crack propagation as a ‘toughening mechanism’ that involves shielding cracks, interlocking fractured surfaces, and deflecting cracks from a straight path. Graduate student Shashank Gupta explained that creating architected concrete materials with high geometric fidelity in building components like beams and columns often requires the use of robots. Robotic additive manufacturing allows for the exploration of complex architectures that are not achievable with traditional casting methods. In Moini’s lab, large industrial robots are used to create full-sized structural components with precision and aesthetics.
To address the issue of fresh concrete deforming under its weight during fabrication, the researchers developed a customized solution. By controlling the concrete’s rate of hardening using a two-component extrusion system within the robot’s nozzle, they minimized deformation and maintained structural precision. The system mixes concrete and a chemical accelerator at the nozzle, allowing the accelerator to expedite the curing process while accurately controlling the structure. This innovation ensures that the lower levels of the architected structure remain intact despite the weight of upper layers being deposited during fabrication.
The study showcases the potential of combining nature-inspired designs with advanced fabrication methods to enhance material properties like strength and crack resistance in concrete. By mimicking the double-helical arrangement found in coelacanth fish scales, the researchers were able to significantly improve the crack resistance of the concrete components. The use of robotic additive manufacturing enables the creation of complex architectures that are both structurally sound and visually appealing, showcasing the capabilities of industrial robots in large-scale construction projects.
The development of a toughening mechanism in crack propagation, as described in the study, highlights the innovative approach taken by the researchers to address structural integrity in concrete components. By combining shielding, interlocking, and deflection mechanisms, the team was able to enhance the crack resistance of the architected concrete materials. The integration of advanced fabrication techniques, such as robotic additive manufacturing, allowed for precise control over the material deposition process, resulting in improved structural performance and durability.
Overall, the research conducted by the Princeton Engineering team demonstrates the potential of nature-inspired designs and additive manufacturing processes in enhancing the properties of concrete components. By leveraging the unique geometric arrangements found in natural structures like fish scales, the researchers were able to significantly increase the crack resistance of concrete beams and columns. The use of industrial robots in the fabrication process enabled the creation of intricate architectural designs that would be challenging to achieve using traditional casting methods, showcasing the benefits of advanced fabrication techniques in modern construction practices.