Complex concrete shapes can turn formwork into a substantial fabrication task. A peer-reviewed study published on 9 October 2026 explores a different route: print a wax-foam shape close to its final geometry, then machine the surface before casting concrete. The full-scale trial is useful because it records both a successful casting and the production problems that still need solving.
Research reviewed: Jonischkies and colleagues, Frontiers in Built Environment. This article summarises their findings and offers Civil Insight’s practical assessment.
What the researchers tested
The team combined robotic wax-foam extrusion, 3D scanning and CNC milling in a digital manufacturing workflow. Wax was used for the complex parts of a hybrid mould, while timber panels formed simpler surfaces. They characterised wax behaviour, calibrated printing conditions and produced a curved precast seating-step element weighing approximately 650 kg.
The important distinction is between printing the concrete and printing its mould. Here, concrete was cast conventionally into the completed hybrid formwork. The research therefore concerns formwork production and recovery, with potential relevance to bespoke precast work.
The main findings
Material demand fell against a solid-wax reference. The authors report approximately 80% less wax demand for the near-net-shape route than for the comparable solid block they estimated would otherwise be cast and machined. This comparison concerns wax production routes. It does not demonstrate an 80% saving against plywood, conventional formwork costs or carbon emissions.
Cooling remained a programme constraint. Printing took about 8 hours 45 minutes, followed by 3 days 21 hours of cooling from 65°C to 25°C. The authors contrast this with an expected cooling period exceeding two weeks for a comparable solid-wax block. That reference period and their proposed future improvements should be distinguished from the measured prototype results.
A complete concrete element was produced, with surface defects. The mould remained stable during casting. However, layer-related marks, local discolouration and uneven texture meant the element did not fully achieve its specified German SB3 fair-faced finish without remedial treatment.
Material recycling succeeded; direct mould reuse did not. Damage during demoulding prevented another equivalent-quality casting from the same mould. The wax was recovered through remelting, filtration and reprocessing. Recovering a material and repeatedly using the finished mould are different production outcomes.
Why the evidence is useful
The study follows the process through casting and demoulding rather than stopping at a printed sample. That exposes interfaces which matter in a precast factory: cooling distortion, bonds between printed layers, machining, assembly and release. Reporting these problems makes the demonstration more informative than a photograph of a finished shape alone.
The hybrid approach also deserves attention. A production team could investigate digital fabrication for difficult geometry while retaining familiar methods for simpler faces. Civil Insight’s interpretation is that this allocation of manufacturing effort is a more useful question than whether every part of a mould can be printed.
Limitations that matter in production
This was a feasibility demonstration with one full-scale case, not a broad production trial. Warping, cracking, layer separation and manual repairs affected the workflow. Although scanning supported machining, the authors did not provide a quantitative comparison of the design geometry against the final concrete element. Visual reproduction of a shape therefore cannot establish a general manufacturing tolerance.
The mechanical tests also do not settle long-term deformation, creep or the behaviour of all joints and layer interfaces under sustained loading. Short-term specimen strength is only one part of formwork performance. The authors identify these gaps rather than demonstrating an established design system for unrestricted use.
Environmental claims need similar care. Less wax in a preform is measurable progress, but melting, printing, cooling, machining and recovery all belong in the assessment. This study does not establish a complete comparative life-cycle advantage over conventional formwork. A single demonstrated recovery cycle also cannot establish long-term performance over many recycling cycles.
What construction professionals can take from it
For a precaster considering a development trial, the useful evaluation would cover the whole production cycle: acceptable concrete finish, verified dimensions, first-pass yield, repair hours, waiting time, demoulding damage and recovery effort. These measures would show whether geometric flexibility creates value after the less visible work is counted.
Project selection would matter. A bespoke curved component may justify development effort that a repetitive standard element would not. Before wider adoption, a manufacturer would need repeated castings, documented acceptance criteria and a cost comparison using its own labour, equipment and production constraints. These are Civil Insight’s proposed evaluation priorities, rather than additional outcomes measured in the paper.
Civil Insight assessment: the work demonstrates a credible manufacturing route for complex hybrid formwork. Its strongest contribution is showing where the process works and where it still fails. Better interlayer bonding, surface consistency and damage-free release are central to turning the prototype into a repeatable production method.
Original paper and image credits
Jonischkies, S., Mainka, J., Kloft, H., Diesslin, R. and Hack, N. (2026). A novel formwork technology based on wax foam 3D printing and CNC milling. Frontiers in Built Environment, 12:1934051. Published 9 October 2026. Read the full open-access paper and DOI.
Featured image: the authors’ wax-foam printing unit, Figure 2. Supporting images: demoulding and the concrete element, Figure 13. © 2026 Jonischkies and colleagues, reproduced with attribution under CC BY 4.0. One co-author is employed by the equipment partner, Herrhammer GmbH; the paper discloses that relationship.
