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3 ways to automate the production of precast concrete elements using fixed moulds

2025-05-07

1.Bench production:

    In this method, the entire production cycle takes place on a casting bed (cassette-installation) that has integrated devices like vibrating equipment and steam curing systems.

    Concrete is supplied from a computer-controlled batching and mixing plant and discharged into the hoppers of static or mobile casting machines.

    After installing the reinforcement cage, the concrete is cast, levelled, and compacted into moulds secured to vibrating tables.

    Production plants typically have teams specialized in different parts of the process, such as assembly, reinforcing, casting, finishing, stripping, cleaning, and oiling of the moulds.

    Gang moulds are an economical solution for producing large numbers of similar elements side by side or end to end, commonly used for beams, lintels, and sleepers.

    Battery casting is similar to gang casting but is used for different precast elements like wall elements, which are cast vertically side by side in mould assemblies containing twenty to over a hundred cells.

    The Level of Automation (LoA) for this type of production generally ranges between LoAm 1 and LoAm 4, with the highest LoAm observed in the batching and mixing plant, concrete transport, and concrete distribution.

    Beyond conventional formwork, digital construction techniques like adaptive moulds, binder jetted, or 3D printed free-form moulds can be applied for manufacturing free-form structures, offering a higher LoA. For example, adaptive moulds can adjust or be printed according to CAD files (LoAm 5, LoAc 7). The ADAPA Adaptive Mould™ is given as an example that can fabricate single-curved and double-curved surfaces based on CAD files, reducing the need for one-off tooling. It is also possible to 3D print formwork before or simultaneously with concrete casting.

Automated production of precast concrete elements.jpg

2.Extrusion with stationary matrix:

    A pre-approved concrete mixture, typically a fine concrete with suitable consistency (sometimes fibre-reinforced), is continuously fed into an extruding machine and pressed through a stencil before hardening.

    Compared to bench production, this method generally has a higher LoAm (LoAm 5) because no additional work is needed.

    Concrete spacers are an example of elements commonly produced using this method.

 

3.Injection compressing in press mould:

    This method is used by plants transitioning from mass production to mass customization, allowing customers to choose variations of the end product while maintaining a mass production concept. This is common for products like cobble stones and paving stones.

    The cement mix from the batching and mixing plant needs to be semi-dry (also called earth-moist).

    The mixture is conveyed to the machine, which dispenses portions into a single mould used throughout the production process.

    The concrete mixture is compressed and vibrated at a high frequency within the mould.

    The mould is stripped after only a few seconds, and the finished products retain their shape.

    Some plants implement quality control measures before curing, such as microwave testing and bulk density testing (LoAm 5, LoAc 5).

    Mass customization plants can produce a large number of paving stones daily (up to 200,000 per machine). After curing, stones are sorted for defects, which can be done manually (LoAm 1, LoAc 1) or using sorting robots (LoAm 5, LoAc 7).

Highly automated production of precast concrete elements using fixed moulds.jpg

These methods represent different approaches to automated precast concrete production using fixed moulds, ranging in complexity and automation levels, and are suited for various types of concrete elements and production scales.

 

References

State of practice of automation in precast concrete production