The application of foam 3D printing in the building sector is being investigated by a team at ETH Zurich’s Digital Building Technologies (DBT) section.
The researchers devised a new way of casting geometrically optimized concrete slabs by 3D printing complicated formwork using mineral foam.
The recyclable foam was developed at ETH Zurich with the cooperation of insulation specialist FenX AG. It can print both functional, stay-in-place formwork as well as temporary, recyclable formwork.
When compared to a traditional, filled-in concrete slab, the DBT unit claims that its resource-efficient formwork can save up to 70% of the concrete required.
The optimized slabs, in addition to being lighter, are said to have better-insulating properties.
Formwork is being replaced with foamwork.
The term “formwork” refers to the process of producing a mould or cast into
which concrete can be poured.
Traditional formwork is typically made of wood, but steel,
glass-fibre-reinforced plastics and other materials can also be utilized.
The age-old skill is ideal for casting simple structures like walls or columns,
but it becomes very time- and labour-intensive when more complicated,
intricate geometries are involved.
It is now possible to produce geometrically complex formwork pieces that were previously wasteful or just impracticable by using foam 3D printing instead.
Beyond the performance benefits,
the approach also has sustainability benefits,
as it uses less material and energy, both of which are ongoing issues in the construction industry.
There are four foam elements in all, each with a different shape.
The DBT team 3D printed a set of prototype form elements and utilized them to cast a concrete slab to demonstrate its new process. There were a total of 24 formwork parts, each of which came in one of 12 different shapes.
All of the foam parts were created with the help of an ABB robotic arm and a unique foam extrusion rig.
The foam parts were then set in a timber perimeter,
which was subsequently filled with ‘ultra-high-performance fibre-reinforced concrete.’
The finished cast slab was 2m by 1.3m and had a ribbed design with point supports in each corner.
The web-like rib layout matched the isostatic lines obtained from the slab’s major stress pattern,
making it look a lot like a topologically optimized part.
In other words, the concrete was cast where the stress was greatest,
maximizing the compressive strength of the slab while using the least amount of material possible
From Academia to Real World Applications
Construction 3D printing has already found its way out of academia and is now being used in the real world. Indonesia’s Public Works and Public Housing Ministry (PUPR) began testing concrete 3D printing
earlier this month to address the country’s desire for inexpensive infrastructure.
The PUPR employed the technology to layer-by-layer erect structures from mortar in experiments conducted with construction business PT. PP (Persero) Tbk and start-up Autoconz.
In other news, in the Dutch city of Nijmegen,
the world’s longest 3D printed concrete pedestrian bridge was recently completed.
The tower, which spans 29 meters,
was created by Rijkswaterstaat,
the Dutch Directorate-General for Public Works and Water Management, and designer Michiel van der Kley in honour of Nijmegen’s 2018 designation as European Green Capital.
Source: ETH Zurich
