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Over a century ago, the invention of reinforced concrete ignited a quest to formulate an architectural expression for the new technology. Joseph Monier, a French gardener, experimented with the material in whimsical bridges and landscape architecture. Auguste Perret later explored the material’s potential for civic and religious spaces. His office became a global center for architects interested in concrete modernism, attracting a young Le Corbusier and Turkish modernist Burhan Arif Ongun. Similarly, as 3D printing proliferates, Leslie Lok and Sasa Zivkovic — the duo behind architectural studio HANNAH and associate professors of architecture at Cornell University — are exploring the applications of robotic construction methods for concrete.
Ashen Cabin by HANNAH, Ithaca, NY
At present, automatization and 3D printing are comparably upturning conventions in the building industry with the promise of replacing mass fabrication with near-infinite customization. HANNAH’s investigation of the new material began with Additive Architectural Elements — a series of design experiments that poke at the ornamental and structural possibilities of this emerging construction process. The highly tactile Elements begins to answer what 3D printed concrete should look and feel like, probing its structural capacity and seeking an honest language that showcases the process itself.
The influence of Elements on the firm’s prototype 3D printed building, Ashen Cabin, is clear. Intense striations remaining from the printing and ornamental floor patterns reflect the variety of expressions in Elements, with a clear preference for corbeled structural forms that now compose the foundation of the cabin. It is not surprising that HANNAH’s designs are, among many others, inspired by Brutalism’s honest and explicit use of material.
Ashen Cabin is at once spontaneous and incredibly precise. The width of each concrete layer is altered by variables such as humidity and temperature that can affect printing and curing. On the corners of the fireplace, concrete dribbles bubble down the sides, capturing a moment of the material’s own volition. Maintaining what could be considered minor imperfections demonstrates a sensitivity to the emergent architectural language of 3D printed concrete and delightfully contrasts with the rest of the structure’s carefully calibrated design.
Formal and aesthetic implications aside, Lok and Zivkovic envision the technology as unlocking new material and social possibilities. In addition to concrete, the cabin’s eponymous ash wood is used extensively, a material available in abundance thanks to mass infestations of American forests by the Emerald Ash Borer. Generally, infested ash trees are mature, with a warped shape and subsequent undervaluing by the lumber industry, which relegates them for waste or firewood. In a reversal of conventional sawmill processes — which prize efficiency and uniformity — HANNAH scanned individual pieces of lumber and precisely milled them employing a robotic arm. The curved wooden slats were then assembled as siding, complementing the idiosyncrasies of the printed foundation.
Lok enumerates the ways that 3D printed concrete might subvert the broader building industry: “There is a traditional process where the contractor and designer build and then the homeowner purchases the house. That will change because the potential for mass-customized housing is immense. We can think about housing units that used to be quite homogenous, modular, and repetitive which can now be customized locally within each unit.”
Meanwhile, the use of this technology is also poised to expand as it meshes well with contemporary frameworks, given the “increased digitization of planning and the architectural design process.” Zivkovic elaborates that, “in some ways, 3D printing really works well with the current process and tools that we are using.”
As the dream of customized mass housing appears closer, the pair increasingly finds themselves working outside of design, engaging with electrical engineers, urban planners, and city officials. “How do we make it [3D concrete printing] accessible for others in the building industry and city who are not familiar with the technology?” is a challenge HANNAH is confronting as the firm seeks approval for its first permitted residence in an undisclosed location.
Emerging technologies have long been connected with efforts to house the masses affordably. Experimental projects like Cement City, a 1916-17 neighborhood of concrete workers’ houses in Pennsylvania and Walter Gropius’s better known Dessau-Törten Estate from the mid-1920s attempted to leverage new materials to improve housing conditions. But, then, as now, the potential of technology to achieve positive social change is inevitably linked to the socio-economic and political systems in which it operates. Concerns remain about how the automatization associated with 3D printing concrete will impact the livelihoods of construction workers, architects, and contractors.
Regardless of the technology’s social potential, HANNAH is not ignorant of the climatic costs and benefits of concrete. Zivkovic details their approach to the material, “The way we look at this is that concrete itself is perhaps a bridge technology, down the road one has to develop more sustainable alternatives to 3D print with, geopolymers or mud soil, all of these things are a possibility.” Even in its early stages, 3D printing concrete offers distinct benefits. The need for formwork, the most expensive and wasteful aspect of traditional concrete construction, is eliminated by directly printing concrete. In traditional concrete buildings, immense supports had to be constructed to carry the structural weight while the concrete was poured and cured. This process unifies buildings as structurally diverse as the Sydney Opera House and Hoover Dam.
HANNAH predicts the sector’s explosive growth in the near future. Commercial projects utilizing this technology are now underway in The Netherlands, and in Italy, a similar process was recently used by Mario Cuccinelli to print a house from clay. While 3D printing seems set to challenge many traditional building practices, it remains to be seen whether the benefits that HANNAH pioneered with Ashen Cabin — utilizing waste materials, careful attention to the medium’s language and site customization — will be applied on a larger scale as the technology is fully commercialized.
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