C-FORM fire protection recess
Formwork element with integrated fire penetration seal

The new C-FORM fire protection recess from Hensel is a prefabricated formwork made of concrete using a 3D printing process with an integrated fire protection bulkhead. All EN-approved HENSOTHERM® and HENSOMASTIK® product systems for the construction of fire protection penetration seals with European Technical Assessment (ETA) or General construction technique permit (allgemeine Bauartgenehmigung, aBG) with 2 x 50 mm or 1 x 60 mm mineral fibre boards from Hensel can be pre-installed.

How does concrete 3D printing work?

Concrete 3D printing, also known as additive concrete construction or concrete additive manufacturing, is an innovative technology that makes it possible to produce complex structures from concrete in a single step. The common abbreviation for concrete 3D printing is 3DCP for 3D Concrete Printing or 3D Construction Printing. But how does concrete 3D printing actually work?

3D printing with concrete essentially works in a similar way to other forms of additive manufacturing, in particular it is comparable to the 3D printing of extruded plastics, but with specific adaptations for processing concrete materials. In fused deposition modelling (FDM) of plastics, extrusion refers to the process in which the printing material, usually a plastic filament, is heated and forced through the nozzle of the print head to form a thin layer of the object, which is then built up layer by layer to create the final 3D object. In contrast to conventional construction methods, where concrete is poured into a formwork or mould, concrete 3D printing is built up layer by layer by extruding special concrete mixtures that have the right flowability and ensure rapid curing without the need for significant heating as with plastic filaments.

For production, a digital model of the C-FORM fire protection recess with the desired dimensions is first created to control the 3D printer. This model is then broken down into small layers that are to be printed one after the other. The process of converting a 3D model into a series of layers or slices is therefore also known as slicing.

The slicing software plays a central role in the 3D printing process. It regulates the thickness of each layer that is printed and the printing speed. A smaller layer height leads to higher resolution and finer details, but also increases the printing time. A higher speed can shorten the print time, but possibly at the expense of print quality. It is important that a concrete layer has sufficient time to cure so that it develops enough strength to support the weight of the overlying layers without the structure deforming or even collapsing. A special concrete mix was specially developed for the C-FORM fire protection recess to optimise the ratio between compression speed, strength and maximum construction height.

Once all the settings have been made, the software generates the so-called G-code, which controls the precise movements and operations of the 3D printer. The G-code contains instructions for each layer and movement of the print head as well as for temperatures and other relevant parameters. With the generated G-code, the 3D printer can now build up the C-FORM fire protection recess layer by layer.

After complete drying and curing, the desired product system for fire protection penetration seals is installed with the specified positions of the mineral fibre boards by trained specialists using original Hensel products. The mineral fibre boards coated with the waterproof fire protection coating HENSOMASTIK® 5 KS Farbe/viskos are force-fitted into the C-FORM fire protection recess and bonded at the sides with HENSOMASTIK® 5 KS Spachtel filler and sealed to prevent the penetration of moisture. Finally, if necessary, protective films are applied to additionally protect the C-FORM fire protection recess from waterlogging and dirt. These are particularly recommended if the mineral fibre board layers are not flush with the component surface and water could collect in the stripping element.

3D printing is an innovative technology that is also becoming increasingly important in the construction industry. Precast moulds produced using the 3D printing process are just the tip of the iceberg. Overall, concrete 3D printing offers new possibilities for the construction industry and opens up exciting opportunities for the design of architectural structures. Using concrete 3D printing, impressive concrete structures and complete buildings can be realised that are aesthetically pleasing as well as stable and durable.

Another important aspect of concrete 3D printing is its sustainability. Through the targeted use of materials and the reduction of waste, the consumption of resources can be minimised and the environmental impact reduced.

Overall, concrete 3D printing offers enormous potential for the construction industry and promises numerous advantages in terms of efficiency, flexibility and sustainability. It is expected that this innovative technology will play an increasingly important role in the design and construction of buildings and infrastructure in the future.

BIM and C-FORM – A Great Team!

Building Information Modeling (BIM) is a method for digitally planning, building, and managing construction projects. It involves a model that consolidates all relevant data and information of a building in digital form, covering the entire lifecycle of a building or construction project.

In conjunction with BIM, the C-FORM prefabricated formwork element with integrated fire penetration seal can improve the construction process in several ways.

Accuracy and Precision: By using BIM, all openings and slots can be precisely planned and dimensioned in the digital model. Prefabricating the recess elements based on the exact specifications of the BIM model ensures they fit perfectly. This significantly reduces errors and rework on the construction site.

Coordination and Collaboration: BIM promotes interdisciplinary collaboration between architects, engineers, and construction companies. All stakeholders can use the model to ensure that the openings for technical building services (TBS) lines and the prefabricated recess elements are correctly planned and integrated into the overall structure. This minimizes communication errors and improves coordination on the construction site.

Increased Safety and Compliance: Fire protection is a critical aspect of any construction project. By integrating fire protection seals into the prefabricated formwork elements, it ensures that all necessary fire protection regulations and standards are met from the start. This reduces the risk of defects and ensures that the building meets all legal and safety requirements. Fire protection is addressed early in the construction phase and ensured in every construction phase, as also empty fire penetration seals already meet future fire protection requirements.

Time Efficiency and Cost Savings: Integrating fire protection barriers into the prefabricated elements saves significant time, as these tasks no longer need to be performed separately on the construction site. This shortens the construction time and reduces labour costs since fewer specialized workers are needed on-site.

Quality Control and Consistency: Prefabrication of the elements, including fire protection barriers, occurs in a controlled environment, ensuring higher and consistent quality. This leads to better execution and fewer reworks or corrections on the construction site.

Simplification of Construction Processes: On-site, no additional materials and tools are required for the installation of the prefabricated elements. This simplifies logistics and reduces the complexity of construction processes.

Improved Coordination and Integration of Fire Protection: In the BIM model, all fire protection requirements can be planned and visualized in detail. The prefabricated C-FORM fire protection recesses can then be manufactured precisely according to these specifications, facilitating integration into the overall structure and improving coordination between different trades.

Reduction of Errors and Rework: Prefabrication and integration of fire protection barriers eliminate potential sources of error that could arise from separate on-site installation. This is especially true when deviating product systems are installed during the execution phase that cannot meet the carefully planned parameters (e.g. minimum distance requirements, media types, dimensions of services, and insulation materials). Pre-selecting the appropriate product system for fire protection barriers concerning planned line occupancy and distances reduces the need for rework and improves the overall efficiency of the construction project.

Sustainability and Environmental Protection: Prefabrication and integration of the elements minimize material waste, as everything is precisely manufactured to size and only the amount of material actually needed is used. This contributes to more sustainable construction and reduces the ecological footprint of the project.

Maintenance and Inspection: Documentation and traceability in the BIM model are facilitated, as all openings and fire protection barriers, along with specifications, are included in the model. This greatly simplifies future retrofitting and inspections.

In summary, integrating fire protection barriers into prefabricated, precisely fitting elements further optimizes the construction process by increasing safety, saving time and costs, improving quality and consistency, and simplifying construction workflows.