Editing Mycelium (section)

===Construction material===
Mycelium is a strong candidate for sustainable construction primarily due to its lightweight biodegradable structure and its capacity to be grown from waste sources. In addition to this, mycelium has a relatively high strength-to-weight ratio and a much lower embodied energy compared to traditional building [[Mycelium-based materials|materials]]. Because mycelium takes the form of any mold it's grown in, it can also be advantageous for customization purposes, especially if it's employed as an architectural or aesthetic feature. Current research has also indicated that mycelium does not release toxic resins in the event of a fire because it has a charring effect similar to mass timber. Mycelium plays an interesting role in acoustic insulation, boasting of an absorbance of 70–75% for frequencies of 1500&nbsp;Hz or less.<ref name="Livne">{{Cite journal | vauthors = Livne A, Wösten HA, Pearlmutter D, Gal E |date=2022-09-19 |title=Fungal Mycelium Bio-Composite Acts as a CO 2 -Sink Building Material with Low Embodied Energy |url=https://pubs.acs.org/doi/10.1021/acssuschemeng.2c01314 |journal=ACS Sustainable Chemistry & Engineering |language=en |volume=10 |issue=37 |pages=12099–12106 |doi=10.1021/acssuschemeng.2c01314 |hdl=1874/423146 |s2cid=252020516 |issn=2168-0485|hdl-access=free }}</ref>

==== Strengths and weaknesses ====

Mycelium [[Biocomposite|bio-composites]] have shown strong potential for structural applications, with much higher strength-to-weight ratios than that of conventional materials due primarily to its low density. Compared to conventional building materials, mycelium also has a number of desirable properties that make it an attractive alternative. For example, it has low [[thermal conductivity]] and can provide high acoustic insulation. It is biodegradable, has much lower embodied energy, and can serve as a carbon sink, which makes mycelium bio-composites a possible solution to the emissions, energy, and waste associated with building construction.

While mycelium proposes interesting implications as a structural material, there are several significant disadvantages that make it difficult to be practically implemented in large-scale projects. For one, mycelium does not have particularly high compressive strength on its own, ranging from 0.1-0.2 MPa.<ref name="Dessi">{{cite journal | vauthors = Dessi-Olive J | title = Strategies for Growing Large-Scale Mycelium Structures | journal = Biomimetics | volume = 7 | issue = 3 | pages = 129 | date = September 2022 | pmid = 36134933 | pmc = 9496270 | doi = 10.3390/biomimetics7030129 | doi-access = free }}</ref> This is in stark comparison to traditional concrete, which typically has a [[compressive strength]] of 17-28 MPa. Even more, because mycelium is considered a living material, it holds specific requirements that make it susceptible to environmental conditions. For instance, it requires a constant source of air in order to stay alive, needs a relatively humid habitat to grow, and cannot be exposed to large amounts of water for fear of contamination and decay.

==== Mechanical properties ====

Three separate fungi species (''Colorius versicolor'', ''Trametes ochracea'', and ''[[Ganoderma sessile]]'') were mixed independently with 2 [[Substrate (chemistry)|substrates]] (apple and vine) and tested under separate incubation conditions in order to quantify certain mechanical properties of mycelium. In order to do this, samples were grown in molds, incubated, and dried over the course of 12 days. Samples were tested for water absorption using [https://www.astm.org/c0272_c0272m-18.html ASTM C272] guidelines and compared against an [[Polystyrene|EPS]] material. Tiles of uniform size were cut from the fabricated mold and put under an Instron 3345 machine going at 1&nbsp;mm/min, up until 20% deformation.<ref name="Attias">{{Cite journal | vauthors = Attias N, Danai O, Abitbol T, Tarazi E, Ezov N, Pereman I, Grobman YJ |date=2020-02-10 |title=Mycelium bio-composites in industrial design and architecture: Comparative review and experimental analysis |journal=Journal of Cleaner Production |language=en |volume=246 |pages=119037 |doi=10.1016/j.jclepro.2019.119037 |bibcode=2020JCPro.24619037A |s2cid=210283849 |issn=0959-6526}}</ref>

Throughout a 4 stage process, the impact of various substrate and fungal mixes was investigated along with properties of mycelium such as density, water absorption, and compressive strength. Samples were separated into two separate incubation methods and inspected for differences in color, texture, and growth. For the same fungi within each incubation method, minimal differences were recorded. However, across disparate substrate mixtures within the same fungi, colorization and external growth varied between the test samples. While loss of organic matter was calculated, no uniform correlation was found between substrate used and chemical properties of the material. For each of the substrate-fungi mixtures, average densities ranged from 174.1&nbsp;kg/m<sup>3</sup> to 244.9&nbsp;kg/m<sup>3</sup>, with the Ganoderma sessile fungi and apple substrate combination being the most dense. Compression tests revealed the Ganoderma sessile fungi and vine substrate to have the highest strength of the samples tested, but no numerical value was provided.<ref name="Attias" /> For reference, surrounding literature has provided a ballpark estimate of 1-72 kPa. Beyond this, mycelium has a thermal conductivity of 0.05–0.07W/m·K which is less than that of typical concrete.<ref>{{Cite journal | vauthors = Yang Z, Zhang F, Still B, White M, Amstislavski P |date=2017-07-01 |title=Physical and Mechanical Properties of Fungal Mycelium-Based Biofoam |journal=Journal of Materials in Civil Engineering |language=en |volume=29 |issue=7 |pages=04017030 |doi=10.1061/(ASCE)MT.1943-5533.0001866 |issn=0899-1561}}</ref>

==== Construction ====

The construction of mycelium structures is primarily categorized into three approaches. These include growing blocks in molds, growing in place monolithic structures, and bio-welded units. The first approach cultivates mycelium and its substrate in forms, after which it is dried in ovens and then transported and assembled on site. The second approach uses existing formwork and adapts [[cast-in-place concrete]] techniques to grow monolithic mycelium structures in place. The third approach is a hybrid of the previous two referred to as myco-welding, where individual pre-grown units are grown together into a larger monolithic structure.<ref name="Dessi" />

Studies using grow-in-place methods and myco-welding have explored how to cultivate mycelium and re-use formwork in construction and investigated post-tensioning and friction connections. Research in fabrication has revealed some common challenges faced in construction of mycelium structures, mostly related to the growth of the fungi. It can be difficult to cultivate living material into formwork and it is susceptible to contamination if not properly sterilized. The fungi needs to be kept refrigerated to prevent hardening and properly manage growth and substrate consumption. Additionally, the thickness of fungal growth is limited by the presence of oxygen; if there is no oxygen, the center of the growth can die or be contaminated.<ref name="Dessi" />

==== Environmental impact ====

Researchers have performed [[life-cycle assessment]]s to evaluate the environmental impact of mycelium bio-composites. Life cycle analysis showed the viability of mycelium as a [[carbon sink]] material and as a sustainable alternative to conventional building materials.<ref name="Livne" />  Use of mycelium as a natural adhesive material may provide environmental benefits, as the fungal-based composites that mycelium is used to create are low cost, low emission, and sustainable. These composites also have a wide range of applications and uses, many of which are in industries responsible for significant environmental pollution, like construction and packaging.<ref name="Alemu">{{Cite journal |last1=Alemu |first1=Digafe |last2=Tafesse |first2=Mesfin |last3=Kanti Mondal |first3=Ajoy |date=March 12, 2022 |title=Mycelium-Based Composite: The Future Sustainable Biomaterial |journal=International Journal of Biomaterials |volume=2022 |pages=1–12 |doi=10.1155/2022/8401528 |doi-access=free |pmid=35313478 |pmc=8934219 }}</ref>

Modern construction and packaging materials are industrially fabricated, non-recyclable, and pollutive: wood products lead to severe deforestation and weather fluctuation; cement is nonbiodegradable and causes high emissions both in production and demolition. Mycelium appears to be cheaper and more sustainable than its counterparts.<ref name="Alemu" />

Mycelium’s adhesive properties are largely responsible for its diverse array of applications, as it allows them to bind certain substances together. These properties are products of their biological processes, as they secrete corrosive [[Enzyme|enzymes]] that allow them to degrade and colonize organic substrates. During degradation, mycelium develops a dense network of thin strands that fuse together within the organic substrate, creating solid material that can hold multiple substrates together. This self-assembly property of mycelium is quite unique, and allows mycelium to grow on a wide range of organic material, including organic waste.<ref name="Alemu" />