Living Building Materials (LBMs), are biological systems-inspired materials currently undergoing research and innovation. It focuses on integrating living organisms into construction materials like cement, bricks, concrete, etc. LBMs have properties that resemble self-healing and self-replication, like the human body. However, it’s important to remember that LBMs are still in their early stages of development, and their practical applications are currently limited.
As microorganisms like bacteria or fungi are involved in construction materials, these materials are also known as biological building materials. The involved bacteria can contribute to the self-healing process by either giving rise to minerals to repair cracks or by degrading organic compounds and toxins present in the air. As an example, they could self-heal as your body’s cells do after a mild injury, such as a cut or a bruise. In addition, certain organisms can even create calcium carbonate or other materials that can fill in cracks and restore the material’s strength. The qualities of self-healing construction materials must adjust in response to environmental circumstances such as moisture and temperature.
How are Living Building Materials Made?
Cyanobacteria are a type of bacteria that can perform photosynthesis, like plants. These bacteria are found in aquatic environments, but can also thrive in different habitats. Cyanobacteria colonies can be added to a sand and gelatine solution. These microorganisms collect carbon dioxide and use it to develop and produce calcium carbonate, which is what we know as limestone. A chemical reaction occurs because the calcium carbonate mineralises the gelatine and binds with the sand to create bio-cement or living bricks.
The fascinating thing about such materials is that they can grow and reproduce in suitable conditions. Therefore, producing them organically will boost their production. However, there is one fundamental drawback: the living construction materials cannot reproduce in an arid area as they require wet conditions. Biogenic materials can self-heal, sense and respond to external stimuli like pressure or temperature, and even light up. But keep in mind that engineered living materials have to be fully explored by scientists.
What is the Need to Switch Over to Living Building Material?
Today’s construction methods and materials are wreaking havoc on the environment. ‘Ben Tracy & Analisa Novak’ mentioned in their article published on CBS News that only the cement industry contributes 8% of carbon dioxide emissions globally. Hence, the people developing living building materials aspire to reduce carbon emissions and pollution from the environment while delivering building materials of equal or superior quality to those in the industry. Bacteria-based building materials could aid in the sequestration of surplus atmospheric carbon dioxide gas. For example, our cyanobacteria bricks can absorb carbon dioxide and help protect biodiversity.
Types of Living Building Materials
Following are the types of living building materials present in the construction industry:
01. Biolith Tiles or Biolith Bricks
Biomason’s Biolith tiles or bricks are the commercial Bio-cement products available for purchase. This composite construction material consists of around 85% natural aggregate and 15% Bio-cement material. Bio-mason used Sporosarcina pasteurii bacteria to make biolith tiles because these microorganisms harness carbon similarly to nature, and combining carbon and calcium, they created Bio-cement materials.
Biolith tiles have superior physical properties compared to standard materials for compressive strength, water absorption, freeze-thaw, adhesion, etc. Additionally, they are a safer option for both humans and the environment compared to other cementitious materials.
Biolith can be used in a variety of construction projects, including commercial, residential, and institutional. It has the added benefit of being easy to use and lighter than traditional stone.
02. Self-Healing Concrete or Bio-concrete
Self-healing concrete is also known as bio-concrete. It’s a remarkable material that can fix cracks and damage without any help from outside sources. Bio-concrete is made by adding Genus Bacillus bacteria, calcium lactate, nitrogen, and phosphorus during the concrete mixing process. The microorganisms produce limestone, which helps fill the cracks and effectively repair the concrete structure. It also helps to restore structural integrity and prevent further propagation of cracks, thereby increasing the lifespan and durability of the concrete structure.
If you want to know about the self-healing concrete mechanism, including its advantages and disadvantages, as well as how to select bacteria, you must read Gharpedia’s article, Bioconcrete: New Perspective of Self-Healing Concrete.
03. Mycelium
According to Mitchell Jones & Andreas Mautner et al. (authors of the article “Engineered mycelium composite construction materials from fungal biorefineries: A critical review,” published in Materials & Design journal), in recent years, mycelium, a natural fungi material, has been explored as a conceivable construction material. Mycelium composites are affordable and eco-friendly materials that are gaining popularity for use in construction applications.
It is a rapid-growing matrix that can function as a natural adhesive. When organic waste gets exposed to mycelium, the fungus grows around it and extends roots and fibers that digest waste. Eventually, a firm mycelium block emerges, which is then broken down and placed into molds. These solid mycelium blocks are used for packaging purposes or to create other mycelium composites. Mycelium products can be molded into various items, such as furniture, insulating panels, and bricks, along with improved properties such as lower thermal conductivity and density, higher acoustic absorption, and fire safety.
Benefits of Using Living Building Material
There are several advantages of using living building materials instead of traditional ones. But remember that the benefits of living building materials can vary based on the type of material used and the location of use.
01. Sustainability
Living building materials frequently use renewable resources and have little environmental impact. They are made using natural resources that are easily accessible, thus decreasing the need for non-renewable resources. Moreover, the LBM are either recyclable or biodegradable at the end of their life cycle. This approach helps reduce waste and supports the circular economy.
02. Environment Friendly
Many living building materials have a low environmental impact, as they have zero or very low carbon footprints. For example, biolith absorbs carbon dioxide and has a lower embodied carbon content than conventional materials like concrete. It improves air quality and the health of local inhabitants and workers by reducing the quantity of carbon dioxide in the atmosphere in congested metropolitan regions.
03. Energy Efficiency
Using living building materials can lead to lower energy consumption for heating and cooling due to their superior insulation and thermal performance. Sustainable materials such as mycelium composites may absorb more heat than typical fiberglass-based composites, which helps to make energy-efficient homes or buildings.
04. Improve Air Quality
Living building materials are usually non-toxic and release fewer harmful chemicals than traditional construction materials. This leads to better air quality and gives a healthier place to live.
Application of LBM in Real Project
As per the news published in ‘The Indian Express’, the first building in India made of bio-bricks from agro-waste was launched at the Indian Institute of Technology, Hyderabad. An IIT-H Director has called it a great example of ‘wealth from waste.’ They have turned agricultural waste into sustainable materials, which can then be used to construct environmentally beneficial and cost-effective structures.
On a final note, living building materials are inspired by nature, and their ability to self-repair and adapt gives them several significant benefits and advantages that contribute to a more sustainable and environment-friendly construction industry. However, considering the limitations and challenges associated with living materials, such as specific environmental conditions, is crucial. For example, many living materials, such as those incorporating bacteria, fungi, or plants, require certain levels of humidity and moisture to thrive and grow. Therefore, arid climates with low humidity may not provide the ideal conditions for these materials to flourish.
Although LBMs are still relatively new and proving their viability, they are based on the ancient principles of nature. But it’s definitely a fascinating architectural design and construction industry trend worth keeping an eye on.
Also Read:
12 Green Building Materials That Are Alternatives To Traditional Concrete
Image Courtesy: Image 1, Image 2, Image 4, Image 5(a), Image 5(b), Image 6, Image 8
Author Bio
Nafisa Nazneen Choudhury – Nafisa Nazneen Choudhury is a Civil Engineer (completed B.E. from Assam Engineering College) and is currently pursuing M.Tech in Structural Engineering at National Institute of Technology, Silchar. She is a Technical Content Writer, having over 3 years of experience and has wrote many articles related to Civil Engineering. She is also a Book Author (Authored – “Dream Tales of NNC: Revenge By Murder”) and her book can be found on Amazon. She is also a Guest Author at Gharpedia. Moreover, she is a certified member at Institution of Civil Engineers (ICE) and National Society of Professional Engineers (NSPE). She writes her blogs at her website – nnc2017.wordpress.com. She can be reached on LinkedIn.