Demetris Shammas and Achilleas Xydis
Grotto I Fabrication

Printing: Castles Made of Sand

Digital Grotesque is the first human-scale immersive space entirely constructed out of 3D printed sandstone. A complex geometry consisting of millions of individual facets is printed at a resolution of a tenth of a millimeter to dimensions of a 3.2-meter high, 16 square meter large room. Its geometry was entirely designed through customized algorithms.

Digital fabrication has been one of the key drivers of the latest evolution in architecture. The digitalization of design processes has overcome many of the limitations of industrial mass-fabrication: it allows a large degree of customization paired with high efficiency and precision.

Today additive manufacturing introduces a paradigm shift within digital fabrication: just as with printing ink on paper, the amount of information and complexity of the output is no longer a relevant constraint.


Large Scale and High Resolution

The application of 3D printing technology in architecture has up to now been limited to prototyping or producing small-scale models. Material costs are high, machines have limited scales, and the majority of materials are not strong enough to fulfill construction requirements.

Sand-printing technology has recently emerged as an additive manufacturing technique that overcomes these limitations. This technology is currently used primarily to create casting forms in for industrial applications. Yet it has unique features that make it suitable to create architectural components. Specifically, it allows the fabrication of large-scale elements (currently up to 8 cubic meters in size) with high resolution and accuracy at a competitive price and in short period of time. The printed sandstone elements can be fully self-supporting and can be assembled as a solid construction.


Post-Processing

Natural sandstone has been used as building material since prehistoric times. Cathedrals, temples and other ornamental structures were often constructed with sandstone, as it is a relatively soft material that is easy to work while still having structural resistance. 3D printed sandstone has very similar properties once it is post-processed.

In order to further harden the micro-detailing of the grotto (local parts are thinner than 2mm) and to increase the structural stability, the printed sandstone is infiltrated with resin. This resin closes the pores of the artificial sandstone.

Different coatings have been tested with the goal of creating a smooth surface without a significant loss of detail. In contrast to the highly technological fabrication-process, traditional methods from conservationists of historic Swiss sandstone buildings were applied. Numerous gilding tests were performed, before selecting a traditional coating consisting of pigment, alcohol and shellac.

Assembly

Digital Grotesque's smart bricks are partially hollow with an interior sub-structure to reduce material according to force flow. The bricks have integrated labels as well as alignment and lifting details that enable a mortar-free assembly. All of these features are directly printed into the brick, without the need for any secondary material or processes.

These self-supporting bricks are dimensioned to fit onto standard Euro pallets [120x80cm] for easy transport. While the majority of bricks weigh less than 100kg, a purely manual assembly is generally not possible. Bricks can be lifted and positioned by tying vinyl ropes through their lifting notches, and attaching these ropes to either a forklift or crane. Integrated positioning aids assure an easy alignment when bricks are placed on top of each other

Bricks within a layer can be attached to eather other - effictively tied together - to increase the the overall stability and alignment. This is particuarly the case for strongly cantilevered geometries. Vertical steel tubing can be added for further structural strength.

Outlook

The Digital Grotesque project opens the door to the printing of architecture. It suggests that 3D sandstone printing can be applied both to restoring historic buildings and to constructing new ones. 3D printed elements are within reach not only as fa├žade modules, but also as structural components and entire construction systems.

In combining computational design with 3D sand-printing, unique architectures can be materialized without any manual intervention, and without a loss of detail or information. As a consequence, a new logic for the design of architecture is introduced: one can design not in plan, but fully in three dimensions, and this can be brought to reality in an unseen level of detail and control.

Using this 3D printed technology, ornamentation and free-form geometries are no longer a prohibitive cost factor. The scale of potential thee-dimensional differentiation is brought to a micro-level. This technology promises a larger compositional and constructive freedom and a rationalized fabrication of unique, non-standardized architecture.