3D concrete printing has great potential to fundamentally change construction and thus make it faster, more cost-effective and more efficient - with fewer personnel. Walls are not built or formed by formwork, but are automatically applied layer by layer by the 3D printer. The technological heart of every 3D printing construction site is of course the printer. However, not every commercially available 3D printer can be used to create a habitable building. A 3D construction printer must meet the following requirements:
Printing system and scalability
The first step is to choose the right printing system. Two systems in particular have become established in the construction industry: robot arm printers and gantry systems. Robot arms are usually smaller and ready for use more quickly, but the printing area is limited by the reach of the arm. For larger buildings, the printer must be moved and recalibrated frequently. With gantry systems such as the COBOD BOD2, on the other hand, the 3D printer is set up around the printing area. A print head moves on three axes within the framework to extrude the building material. The BOD2 system can also be configured in a modular manner and can be flexibly expanded depending on the size of the building. This means that buildings up to 13.5 meters long, 9 meters high and a practically unlimited length are possible without moving the printer.
Material compatibility
So far, 3D-printable concrete and mortar have primarily been used in 3D construction printing. There are already several products from various material manufacturers that differ in their composition and properties. For the greatest possible flexibility, the 3D printer should be open to all materials, meaning it should not be limited to certain building materials. This freedom of choice is also determined by the printer's printable grain size, i.e. the maximum size of the stones contained in the printing material. 3D-printable building materials have the special feature that they must have a high green stability in order to be able to stack the individual layers on top of each other while still wet. At the same time, the material must not set too quickly, as the layers must still be able to chemically bond to form a monolithic structure. A reliable process from mixing to extrusion is therefore crucial for a smooth construction process.
Print speed
A high printing speed means that the walls can be completed quickly and is therefore an important criterion when choosing the right 3D printer. With a printing speed of up to one meter per second, the COBOD BOD2 is currently the fastest 3D construction printer on the market. If manual work is to be carried out in the printing area during the printing time, such as inserting stability anchors and empty pipes, the printing speed must be reduced to 25 centimeters per second. The layer times of the various printing materials must also be taken into account so that the individual layers achieve the optimal properties. Based on these factors, the COBOD BOD2 can, for example, produce one square meter of hollow wall in just five minutes.
Precision and flexibility
The nature of the individual layers and thus also of the 3D printed walls is significantly influenced by the 3D printer. Various nozzles offer the possibility of shaping the width, height, shape and structure of the layers as desired. The greatest control over the result is achieved with printers whose extrusion nozzle can be rotated and which automatically aligns itself along the print path when cornering. Nozzles with so-called flaps are also possible, in which sliding fillers smooth the printed layers during the printing process to make later plastering easier. Systems with this type of tangential control offer architects and planners full design control. For a more regular print image and better usability, a print head with a hopper also provides a buffer for the material feed.
Safety and durability on the construction site
3D construction printing can be used as a pure precast solution in precast concrete plants. In our experience, however, the full potential of the construction method only unfolds when it is used directly on the construction site. There are also a number of things to consider here. Various safety regulations must be observed. The COBOD BOD2, for example, is CE-certified, uses IP67-certified cabling and galvanized steel lines. In addition, emergency shutdown buttons are distributed along the entire system to make operation on the construction site as safe as possible. If you want to avoid expensive housing, you should also make sure that the 3D printer is wind and weatherproof and can be cleaned quickly.
User-friendliness and learning curve
At PERI 3D Construction, our goal is to provide construction companies with the technology and know-how to be able to build buildings themselves using 3D concrete printing. However, interested companies should not necessarily have to have robotics engineers on their team. That is why we offer training courses in which you can learn how to operate the COBOD BOD2 3D printer in just six weeks. Training as a bricklayer or reinforced concrete worker is perfectly adequate as a basis. The printer can be operated directly via a browser client on a laptop or smartphone. This means that even short-term changes can be implemented quickly and easily. Sensor-supported assistance systems such as 3D MATCONTROL offer additional transparency and make it easier to achieve consistent results even in changing environmental conditions. The 3D models of the buildings to be printed can also be read by the slicer in any conventional CAD format. This means that use remains beginner-friendly from planning to implementation.
In summary, there are numerous requirements for the 3D printer to be able to successfully print buildings. And there are also similar requirements for the silo mixing pump used, the architectural model, the materials used and other aspects of the process. And yet all of these requirements have already been 100% met many times in order to create buildings using the 3D printing process.
All of these requirements create the basis for a new way of building that is intended to offer the industry significantly more speed and efficiency. The big leap in productivity that the construction industry urgently needs can hardly be achieved through slow, incremental optimization - but only through radical rethinking, innovation and automation. Setting high and well-thought-out requirements on many fronts offers us the basis for holistic solutions that have the potential to fundamentally change construction.
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