Could “Living Building Materials” a/k/a LBM’s Change the Face of Concrete Construction?

The concept of “living building materials” or LBM’s might seem like the stuff of science fiction to some.  But the concept is very real and was introduced by the French back in the 1990’s.  The French were originally researching methods for mineralizing concrete such that it could grow and self-heal similar to how coral reefs grow, heal and continually expand.  Unlike traditional concrete, a coral reef is a living thing, with organisms that continually grow, die, and bio-mineralize, thereby providing the foundation for new organisms to repeat the cycle over and over.  At 1,500 miles long, and covering 133,000 square miles, the Great Barrier Reef is by far the largest LBM in the World.  Since coral reefs can bio-mineralize and produce such an enormous structure, the French sought to apply the same concepts in bio-mineralizing concrete.  The original thinking was not that these LBM’s would replace traditional concrete, but rather would be applied to existing concrete surfaces enabling cracks to self-heal thereby reducing the costs of maintenance and repairs.

There are currently 2 principal forms of LBM’s used in the bio-mineralization of concrete – Biocement and Self-Healing Concrete.  While there are significant  differences between traditional concrete and these LBM’s, there are also similarities.  Unlike traditional concrete, an in-organic static material incapable of adapting to environmental conditions, these LBM’s are alive, and can grow and heal throughout their life cycle which can last over 100 years.  Unlike traditional concrete consisting of sand, stone and Portland cement, these LBM’s contain sand, and materials providing a medium promoting certain micro-organisms to quickly grow and multiply upon the introduction of water.  Unlike the manufacturing of Portland cement which releases large amounts of carbon dioxide into the atmosphere, the micro-organisms in these LBM’s absorb carbon dioxide during the bio-mineralization process.  But like the mineralization of Portland cement during the curing of traditional concrete, the micro-organisms within these LBM’s bio-mineralize with calcium carbonate and become rock hard. Like the organisms in a coral reef, the micro-organisms within these LBM’s grow, die, bio-mineralize, and continually repeat the cycle over and over but at a much faster rate. 

There are likewise differences and similarities between Biocement and Self Healing Concrete.  Biocement contains sand, bacteria or algae, and a growth medium of calcium, nitrogen and phosphate contained within waste from farming and mining, whereas Self-Healing Concrete contains sand, bacteria, and a manufactured hydrogel medium.  Biocement mineralizes through a process known as microbiologically induced calcite precipitation or MICP as originally used by the by the French in researching bio-mineralization, whereas Self-Healing Concrete mineralizes through photosynthesis as developed by the British.  Biocement can mineralize in a variety of environmental conditions, whereas Self-Healing Concrete is highly sensitive to both temperature and humidity.  But both Biocement and Self-Healing Concrete bio-mineralize through reactions between their living micro-organisms and calcium carbonate consuming carbon dioxide in the process.

Despite the potential advantages of Biocement and Self-Healing Concrete, there are a variety of reasons why neither has received wide-spread usage in concrete construction.  First, these LBM’s cost approximately twice as much as traditional concrete and are not readily available.  Second, research has not yet developed reliable procedures for mass-producing these LBM’s to support large scale construction.  Third, research has not developed consistent methods to control unbridled growth of these LBM’s beyond the desired dimensions.  Finally, despite being around for 30+ years, the concept of these LBM’s remains novel, and is relatively unknown and untested to most owners and contractors.  Consequently, the most common usages of these LBM's is typically limited to the original purpose intended by the French, the sealing of cracks and abnormalities in walls, slabs, roads and sidewalks, 

Perhaps the best hope for further development of these LBM’s lies in significant investments being made by the Federal government and the possibility of constructing lunar structures on other planets.  [See, “Is 3D Printing the Future of Construction?”, posted 5/10/23].  Notably, the Department of Defense launched the “Engineering Living Materials or ELM Program" to “develop design tools and methods that enable the engineering of structural features into cellular systems that function as living materials, thereby opening up a new design space for building technology … and to validate these new methods through the production of living materials that can reproduce, self-organize and self-heal.” Obviously, it would be far easier to transport the materials to develop LBM’s into outer space and then use raw materials located on the lunar landscape than it would be to transport the materials and equipment required to mix traditional concrete.