1.3.1. Monolithic Myco-Structures

Monolithic mycelium requires the design and fabrication of complex formworks that permit the fungi to fully grow. Due to such challenges associated with the cultivation of large volumes of live myco-materials and the constructing of formworks to facilitate such growth, very little work on monolithic mycelium has been accomplished in the context of architecture and structural design. In 2016, a master's of science thesis on civil engineering at Miami University, in Coral Gables, FL, USA [42] suggested analytical methods for mycelium-based monolithic domes, but did not validate them through physical means. At a small scale, Dutch artist Eric Klarenbeek demonstrated structural monolithic growth [43] in combination with 3D printing to create furniture. Ecovative experimented with monolithic mycelium and exhibited a chair in 2018 [44] that used a proprietary process that aerated the growing colonies of myco-materials, allowing them to be grown at greater thicknesses. A dissertation from the University of Newcastle in Newcastle upon Tyne, the UK, explored the potential of monolithic mycelium chair structures [45] grown in a conventional plastic formwork. Another interesting application of monolithic mycelium was a functional canoe [46] that was over 2 m long, grown by a student at Wayne State College in Wayne, NE, USA, in 2020.

Beyond these examples in product and furniture design, very few examples of architectural structures have been attempted. A series of three prototype structures was previously presented by the author of this paper [47], proving that grow-in-place monolithic mycelium structures were feasible through novel constructive approaches. Two arch structures (Figure 1) brought to light crucial considerations for successfully growing monolithic mycelium structures. First, the external formwork must be strong enough to support the weight of a wet substrate while maintaining its precise form, it must be composed of removable non-cellulose materials, and must be sufficiently porous to allow promoting the mycelia to breathe. Second, internal reinforcing strategies are advisable to handle eccentric loadings and formal accuracy, and must be composed of a cellulose-based material to permit the mycelia to bind and grow through the reinforcing structure.

A third prototype structure, called the Monolito Micelio (Figure 2), was an architecturalscale monolithic mycelium structure, grown in early 2018 from a one-ton colony of myceliumstabilized hemp procured from Ecovative. The structure was designed and executed in the context of a graduate research seminar at the Georgia Tech School of Architecture. The vaulted pavilion was a critical response to the observed monotony of brick/block-based myco-fabrication methods and built upon the constructive principles of structures before it. The pavilion demonstrated that myco-materials could inherit fabrication logics from cast-in-place concrete techniques, including traditional board formwork and flexible fabric formwork techniques. Importantly, the structure showed that much more work was needed to uncover new and previously unimaginable construction logics that go beyond the architectural cannon of traditional materials.

(**c**) (**d**)

**Figure 1.** (**a**) Formwork for the "Mycoarch" composed of active bent PVC and plastic sheeting; (**b**) completed arch (late 2017, since renamed the "Diamond A Arch"), which collapsed due to inaccurate form and a myco-material matrix that had not sufficiently dried; (**c**) packing the internal reinforcing for the "Thick and Thin Arch" composed of recycled cardboard; (**d**) complete "Thick and Thin Arch" (early 2018) held seventy-five kilograms. Photos by the author. **Figure 1.** (**a**) Formwork for the "Mycoarch" composed of active bent PVC and plastic sheeting; (**b**) completed arch (late 2017, since renamed the "Diamond A Arch"), which collapsed due to inaccurate form and a myco-material matrix that had not sufficiently dried; (**c**) packing the internal reinforcing for the "Thick and Thin Arch" composed of recycled cardboard; (**d**) complete "Thick and Thin Arch" (early 2018) held seventy-five kilograms. Photos by the author.

A third prototype structure, called the Monolito Micelio (Figure 2), was an architec-

tural-scale monolithic mycelium structure, grown in early 2018 from a one-ton colony of mycelium-stabilized hemp procured from Ecovative. The structure was designed and executed in the context of a graduate research seminar at the Georgia Tech School of Architecture. The vaulted pavilion was a critical response to the observed monotony of brick/block-based myco-fabrication methods and built upon the constructive principles of structures before it. The pavilion demonstrated that myco-materials could inherit fabrication logics from cast-in-place concrete techniques, including traditional board formwork and flexible fabric formwork techniques. Importantly, the structure showed that much more work was needed to uncover new and previously unimaginable construction logics The success of the project was also met with numerous failures, which provided the grounds for such a future inquiry. Notably, as part of a super-structure, myco-materials are highly susceptible to expansion and contraction in the face of external elements, making them unsuitable for external use, unless for temporary structures where the lifespan of the structure is understood to be short. Temperature swings and precipitation caused the material matrix of the Monolito Micelio to crack, decay, and become infested by other unfavorable organisms, including potentially dangerous mold (Figure 3). Furthermore, the materials used for the internal reinforcing system were much stronger and rigid than the myco-materials, which further exacerbated the cracking and decay of the structure.

that go beyond the architectural cannon of traditional materials. While, in many regional contexts, there are minor active energy inputs needed to grow myco-materials, their reliance on plastics and molds that have limited reusability presents an ethical dilemma. For example, the plastic-lined plywood and woven nylon fabric formwork system used for the Monolito Micelio was a waste byproduct that resulted in land-fill disposal. The issue of formwork resulting in waste is an issue that has since been taken up by researchers interested in monolithic mycelium. A prototype structure by the multi-disciplinary collaboration in Europe called the FUNGAR project [48] provided early evidence that woven Kagome structures are an advantageous replacement for the polymeric in-situ formworks and molds typically needed to grow myco-materials. Such weaving crafts are globally ubiquitous, formally flexible, and often use natural lignocellulosic materials that are readily available. Such strong porous surfaces allow the fungi to breathe, provide a humid environment, and serve as a source of nutrition for the fungi. In contrast to plastic formworks, myco-weaves encourage mycelia to grow into the formwork and integrate

into the biomass. More recently, the author of this paper grew a two-meter-tall monolithic mycelium column [49] along with students at Kansas State University that used basket weaving techniques. The woven formwork both participated in the visual expression of the column and potentially strengthened the assembly due to the deep bonds between the myco-materials and exoskeleton (Figure 4a). *Biomimetics* **2022**, *7*, 129 6 of 23

*Biomimetics* **2022**, *7*, 129 6 of 23

(**a**) (**b**) (**c**) are highly susceptible to expansion and contraction in the face of external elements, mak-

> **Figure 2.** The Monolito Micelio, grown in early 2018 with students at Georgia Institute of Technology. (**a**) Construction of the wooden internal reinforcing; (**b**) in a manner resembling cast-inplace concrete, mycelilum composite materials were processed on-site with water and nutritional additives and immediately packed into the plywood and geo-textile formwork; (**c**) finished structure, used as a stage and pavilion for a choir performance and exhibited at the School of Architecture. Photos by the author. **Figure 2.** The Monolito Micelio, grown in early 2018 with students at Georgia Institute of Technology. (**a**) Construction of the wooden internal reinforcing; (**b**) in a manner resembling cast-inplace concrete, mycelilum composite materials were processed on-site with water and nutritional additives and immediately packed into the plywood and geo-textile formwork; (**c**) finished structure, used as a stage and pavilion for a choir performance and exhibited at the School of Architecture. Photos by the author. ing them unsuitable for external use, unless for temporary structures where the lifespan of the structure is understood to be short. Temperature swings and precipitation caused the material matrix of the Monolito Micelio to crack, decay, and become infested by other unfavorable organisms, including potentially dangerous mold (Figure 3). Furthermore, the materials used for the internal reinforcing system were much stronger and rigid than the myco-materials, which further exacerbated the cracking and decay of the structure.

The success of the project was also met with numerous failures, which provided the

**Figure 3.** Decay of the Monolito Micelio. (**a**) Cracking and decay of the structure after three months caused by expansion and contraction of the material matrix against the internal reinforcing structure; (**b**) cracking, decay, and infestation of the structure after four months. Photos by the author. **Figure 3.** Decay of the Monolito Micelio. (**a**) Cracking and decay of the structure after three months caused by expansion and contraction of the material matrix against the internal reinforcing structure; (**b**) cracking, decay, and infestation of the structure after four months. Photos by the author.

**Figure 3.** Decay of the Monolito Micelio. (**a**) Cracking and decay of the structure after three months caused by expansion and contraction of the material matrix against the internal reinforcing struc-

 (**a**) (**b**)

deep bonds between the myco-materials and exoskeleton (Figure 4a).

(**a**) (**b**)

While, in many regional contexts, there are minor active energy inputs needed to grow myco-materials, their reliance on plastics and molds that have limited reusability presents an ethical dilemma. For example, the plastic-lined plywood and woven nylon fabric formwork system used for the Monolito Micelio was a waste byproduct that resulted in land-fill disposal. The issue of formwork resulting in waste is an issue that has since been taken up by researchers interested in monolithic mycelium. A prototype structure by the multi-disciplinary collaboration in Europe called the FUNGAR project [48] provided early evidence that woven Kagome structures are an advantageous replacement for the polymeric in-situ formworks and molds typically needed to grow myco-materials. Such weaving crafts are globally ubiquitous, formally flexible, and often use natural lignocellulosic materials that are readily available. Such strong porous surfaces allow the fungi to breathe, provide a humid environment, and serve as a source of nutrition for the fungi. In contrast to plastic formworks, myco-weaves encourage mycelia to grow into the formwork and integrate into the biomass. More recently, the author of this paper grew a two-meter-tall monolithic mycelium column [49] along with students at Kansas State University that used basket weaving techniques. The woven formwork both participated in the visual expression of the column and potentially strengthened the assembly due to the

**Figure 4.** Monolithic and myco-welded structures grown by the author and students at Kansas State University in spring 2021, shown in their final installation sites. The structures were both larger than the available resources for actively drying the structures to stop growth, resulting in the emergence of fruiting bodies on the structures. (**a**) Two-meter-tall woven monolithic mycelium column; (**b**) half-scale myco-welded staircase with visible fruiting bodies that resulted from the two-stage growing process inherent to the myco-fabrication technique. Photos by the author. **Figure 4.** Monolithic and myco-welded structures grown by the author and students at Kansas State University in spring 2021, shown in their final installation sites. The structures were both larger than the available resources for actively drying the structures to stop growth, resulting in the emergence of fruiting bodies on the structures. (**a**) Two-meter-tall woven monolithic mycelium column; (**b**) half-scale myco-welded staircase with visible fruiting bodies that resulted from the two-stage growing process inherent to the myco-fabrication technique. Photos by the author.

### 1.3.2. Bio-Welded Myco-Structures 1.3.2. Bio-Welded Myco-Structures

An increasingly popular technique called "bio-welding", or "myco-welding", involves assembling structures with discreet living parts and growing them together into monolithic wholes. Myco-welding is challenging because it requires two stages of growth. First, individual units are grown from loose inoculated substrates in molds. Second, assemblies of living units are kept in an intended formal configuration for several days, while maintaining necessary sanitary and environmental conditions. Drying and stopping the growth of large assemblies is also a challenge inherent to myco-welding large assemblies. If not completed quickly enough, fruiting bodies often grow on the structure (Figure An increasingly popular technique called "bio-welding", or "myco-welding", involves assembling structures with discreet living parts and growing them together into monolithic wholes. Myco-welding is challenging because it requires two stages of growth. First, individual units are grown from loose inoculated substrates in molds. Second, assemblies of living units are kept in an intended formal configuration for several days, while maintaining necessary sanitary and environmental conditions. Drying and stopping the growth of large assemblies is also a challenge inherent to myco-welding large assemblies. If not completed quickly enough, fruiting bodies often grow on the structure (Figure 4b), which, depending on the application or context, may or may not be desirable. The technique has been demonstrated for small arch structures [50], furniture [51], for making monolithic blocks for use with robotic-controlled abrasive wire cutting [52], and a load-bearing halfscale spiral staircase recently grown by the author and their students [49]. At the large scale, the technique was demonstrated in the form of a triumphal arch at a short-term art installation in Europe [53].

### *1.4. Aims and Scope of This Research*

The applied research described in this paper seeks to expand upon fabrication techniques using myco-materials, with the primary motivation being the excessive waste produced by contemporary construction practices. Among the numerous challenges and limitations associated with the application of myco-materials in architecture, this work focuses on overcoming (1) the challenge of cultivating large colonies of living myco-materials into precise forms and (2) the need for intuitive and re-usable formwork systems that reduce waste byproducts from growing and fabrication processes. The myco-fabrication strategies presented here were developed through the production of prototype structures that demonstrate growing large blocks of myco-materials and assembling them into efficiently formed wall structures. The prototypes share an underlying serpentine geometry deployed into

assemblies that are categorically hybrids between monolithic and brick/block-based. One wall prototype demonstrates units created from myco-welded slabs, while the other revisits the in situ monolithic fabric forming of units that are repeated, stacked, and post-tensioned. Both structures were produced in academic contexts in collaboration with students from the University of Virginia (UVA) and Kansas State University (K-State), under the direction of the author. The prototypes were exhibited publicly in early 2022 at the Biomaterial Building Exposition (BBE) [54].

### **2. Context, Design, and Methods**

The BBE gathered five teams of architect scholars from across the United States to develop and exhibit novel approaches for architectural-scale biomaterial research alongside students at their respective universities. There were three components to the BBE: a collaborative fabrication workshop with students in January 2022, full-scale installations outdoors on the UVA grounds, and an accompanying indoor gallery exhibition at the UVA School of Architecture. An opening symposium fostered discussion between the organizers and exhibitors on how renewable, carbon-sequestering biomaterials could be utilized in contemporary construction, while establishing a multi-institutional scholarly discourse that raised public awareness of novel biomaterial construction.

The UVA's academical village (now a UNESCO World Heritage Site) provided potent inspiration behind the geometry of the two prototype structures presented in this paper. Established and designed by Thomas Jefferson, a prominent feature of the grounds are the brick "serpentine" walls (Figure 5) enclosing the gardens behind each residence pavilion. The structures served as barriers to between the enslaved people and the white university community and to mask the use of slave labor visually and acoustically [55]. The history of serpentine walls at the UVA and their connection to slavery is inescapable. However, serpentine walls are not Jefferson's invention. Straight masonry walls, unless very thick or reinforced, cannot resist lateral loads [56]. Undulating walls can have a much wider footprint, which helps resist lateral loads and can be much thinner than straight walls. Therefore, the motivation to deploy serpentine wall technology for the BBE was to recontextualize the serpentine geometry from its connections to slavery. The prototypes intended to foreground that the inherent properties of myco-materials can through their flexibility, stability, and material efficiency, also act as a means of promoting environmental and human justice. *Biomimetics* **2022**, *7*, 129 9 of 23

**Figure 5.** Serpentine walls designed by Thomas Jefferson and built by slave labor that enclose the gardens at the rear of the residences of the historical academical village at the University of Virginia located in Charlottesville, VA, USA. Photos by the author. **Figure 5.** Serpentine walls designed by Thomas Jefferson and built by slave labor that enclose the gardens at the rear of the residences of the historical academical village at the University of Virginia located in Charlottesville, VA, USA. Photos by the author.
