Researchers Create New Method for 3D Printing Bridge

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.

Shotcrete 3D Printing (SC3DP)

Despite the advancements in textile formwork, the concrete application remained a challenge until the advent of SC3DP. This technique, developed at TU Braunschweig, automates the process of applying concrete. It involves spraying a fine grain concrete or cement paste through a high-velocity nozzle, controlled by robotic arms. The precision of this method ensures strong layer bonding and enables varying layer thicknesses and material properties depending on structural requirements.

The SC3DP technique also addresses another critical issue in traditional construction – the labor intensity and skill dependency of manual shotcrete application. By automating this process, the technology ensures consistent quality and finish of the concrete surfaces.

Seamless Integration of Design and Fabrication

A key aspect of this project was the integration of design, material selection, and robotic fabrication. The process began with computational form-finding to determine the most efficient structural shape and thickness distribution. The formwork’s geometry was then precisely replicated in the CNC-knitted textiles.

In the next step, a thin layer of cement paste was robotically applied to the textile formwork, followed by the strategic placement of continuous glass fiber for reinforcement. Finally, the SC3DP process was employed to apply the structural layer of concrete.

Potential Improvements

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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