Researchers from institutes in Germany and the Netherlands have been working on a method of creating complex geometries in construction. The end result has been demonstrated in the construction of a pedestrian bridge which was made by merging two digital construction technologies, namely CNC-knitted textile formwork, and shotcrete 3D printing (SC3DP). Read on for more information about the research.
CNC-Knitted Textile Formwork
The traditional challenge in constructing complex geometries lies in the cumbersome, labor-intensive process of creating formwork, particularly with materials like concrete. This project has introduced a novel approach using CNC-knitted textiles as formwork. This method not only significantly reduces manual labor but also allows for the creation of intricate, double-curved forms with ease. The textiles, precisely knitted by CNC machines, can incorporate various fibers and design features like channels and openings, custom-tailored to the project’s needs.
Left to right: Foundation placement, Bending active steel rods, Spanning of 3D-knitted formwork, Robotic Shotcrete. (Reference: Rennen et al.)
Shotcrete 3D Printing (SC3DP)
Despite the advancements in textile formwork, the application of concrete continued to pose a challenge until the arrival of SC3DP. This method, which was developed by the TU Braunschweig, automates the process of applying concrete. It involves spraying a concrete or cement paste with fine grains through a nozzle at high speeds, under the control of robotic arms. The accuracy of this method guarantees strong bonding between layers, and also allows layer thicknesses and material properties to adjust based on structural needs.
The SC3DP technique has addressed another significant problem in traditional building – the high labor intensity and skill dependency of manual shotcrete application. By making this process automatic, the technology ensures a consistent quality and finish on concrete surfaces.
Seamless Integration of Design and Fabrication
A significant part of this project was anchoring on the synergy of design, choice of materials, and robotic fabrication. It all started with a computational search for structure to pinpoint the optimal form and uniformity in thickness. The geometry of the formwork was then accurately mirrored using CNC-knit textiles.
The following steps involved the robotic application of a thin cement paste layer over the textile formwork, and strategically positioning continuous glass fiber reinforcements. To conclude, the SC3DP method was utilized to apply the concrete’s structural layer.
Possible Enhancements
While the project marks a significant milestone, the researchers have identified areas for improvement. These include refining the stiffening coat spraying process to minimize textile sagging, optimizing the sequence of construction steps, and improving path planning for robotic spraying to enhance precision and efficiency.
By integrating advanced technologies like 3D knitted formwork, robotic shotcrete spraying, and dynamic fiber reinforcement, the robotic knitcrete project marks a transformative leap in the realm of architectural fabrication, demonstrating how the synergy of digital technologies can revolutionize traditional construction methodologies.
It offers a potential glimpse into a future where our buildings are not just constructed but intricately woven and precisely sculpted, reflecting the perfect blend of technology, art, and engineering.
If you would like to read the research paper, titled “Robotic knitcrete: computational design and fabrication of a pedestrian bridge using robotic shotcrete on a 3D-Knitted formwork”, you can do so over at this link.
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“Why did the 3D printer go to therapy? Because it had too many layers of unresolved issues!”
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