The concept of using biologically derived materials in construction is not new. The earliest shelters were made of bones and animal skin. These materials were later replaced by metals, stones, and plastics. Because of modern technology, the use of biopolymers in construction is no longer limited to usage as additives. It has now expanded to the construction of whole buildings across various scales. Given that metals, ceramics, and plastics are often more energy intensive, resource expensive, and have a higher environmental impact, interest in biologically derived materials has been renewed more than ever before. Biopolymers can be natural, biosynthesized by living organisms; synthetic, made of renewable materials; or microbial, produced by microorganisms.
Architecture requires the use of durable materials, making biopolymers an appropriate choice for construction. Chitin, cellulose, pectin, and casein are some examples of biopolymers that, in addition to being abundantly available on the planet, have a lower environmental impact, and showcase properties of durability and high strength under variable environmental conditions.
The Aguahoja project by Neri Oxman is one such example that aims to arrest the vicious industrial cycle of material extraction and obsolescence. This aim is realized through the use of biopolymer composites that respond to their environment in ways that are impossible to achieve with their synthetic counterparts. The installations make use of some of the most abundant biopolymers on earth, like cellulose, chitosan, and pectin, along with calcium carbonate. These are found in trees, insect exoskeletons, apple skins, and bones.
The structures were digitally designed and robotically manufactured, with the biopolymer composites in constant dialogue with their environment. The smallest changes in response to humidity, heat, and other external conditions, even at the molecular level, can cause dramatic changes in the design and appearance of the installation. It may lighten or darken as the season changes; may become brittle and transparent or remain flexible and tough. In the end, once their purpose is served, these structures will return to the source after dissociating in water.
Biopolymers have also been used as admixtures in cement since ancient times. The earliest examples include the use of vegetable oils in lime mortars, as seen in the works of Vitruvius, dried blood to aerate building materials, or proteins as gypsum binding regulators, which were used by Romans. The use of biopolymer-based admixtures is slowly on the rise in the modern day due to the increasing trend of sustainable development. Lignin, which is among the most abundant biopolymers in nature, is commonly used in construction owing to its easy availability, low cost, and large-scale industrial feasibility. Lignosulphonate, a derivative of lignin, is also frequently used as an additive in mortar and cement. Both lignin and lignosulphonate improve the workability and compressive strength of concrete, making them ideal choices for further improving the quality of cement and mortar.
Material extraction, processing, and discharge have destructive environmental implications. Plant-derived materials, particularly in the form of by-products and waste, combined with additive fabrication practices, offer great potential. Fungal mycelium is one such material, which requires the use of additive manufacturing and computational design. The main components of mycelium composites are cellulose, chitin, lignin, and hemicellulose. Its good thermal properties, and compression and tension resistance make it an ideal research option for alternative construction materials.
Bringing to life, this idea of using fungal mycelium in architecture is the brick research group’s MycoTree. Since mycelium has a dense network, it binds the substrate into a structurally active material composite. Furthermore, mycelium follows a metabolic cycle, allowing for the composting of the whole installation, or its parts after their intended purposes are fulfilled.
Highly sophisticated design tools, in addition to computational design, allowed for the creation of this efficient and experimental structure. It further enabled the viewers and the researchers alike to realize the potential of “low-strength” materials as structural elements, and the importance of designing with the flow of forces. The geometry of this structure was designed using 3D graphic statics, a method that extends the two-dimensional structural design techniques to spatial systems. The MycoTree is polyhedral by construction, does not require optimization and the structure’s complex nodes can be materialized using developable surfaces, which may be cut from sheet material. Utilizing only load-bearing mycelium components and bamboo, the example of this branched structure opens up endless possibilities for using weaker, more environmentally sound materials for achieving structural stability.
Although a relatively under-researched field, biopolymers as construction materials offer a plethora of opportunities for using regenerative resources in combination with proper structural design, allowing for a more sustainable construction industry. In addition to having a lower carbon footprint, structures made up of biopolymers are biodegradable and ultimately go back to the earth, marking a future where structures are not built but grown. The aforementioned examples also leave us to question convention and think outside the box, because ‘modern-day problems require modern solutions’.
|Article title:||University of Stuttgart biopolymers as construction material of the future?|
|Article title:||Block Research Group|
|Website title:||Parametric House|
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