In the heat of the moment, in the middle of an argument, it is understandable to assert a fact that seems self-evidently untrue to be a contrarian.
This appeared to be the case on an episode of TalkRadio TV, where host Mike Graham asserted that you could grow concrete when arguing with a carpenter about sustainability. He then ended the interview after less than a minute.
This, given how concrete is made and how concrete repairs are typically applied, appears to be a truly ludicrous assertion to make. However, several different research teams have been hard at work attempting to do just this.
How Is Concrete Made?
Concrete has been made in largely the same way since the 1850s when William Aspdin took his father’s invention, portland cement, and accidentally added calcium silicates to improve the finished product.
This cement is combined with aggregate, a mix of sand, gravel, slag and crushed stone and water to create a slurry that is mouldable until it dries, making it one of the most used construction materials in the world.
There are slightly different mixes and techniques available but concrete for the most part is a product of these components.
Given the typical ingredients found in concrete, it does seem like there is a place where it is possible to grow concrete.
However, there has been some research in the field of bioengineering to create what has sometimes been described as “living concrete”, although the term is somewhat controversial.
This has historically taken two separate forms; self-healing concrete and living building materials.
Self-Healing Concrete
The concept of a concrete mix that can repair itself has been a large part of engineering research for the past decade, as it means that small imperceptible cracks can be quickly and efficiently patched before they have a chance of risking structural integrity.
The main principle behind this is that certain additives are mixed into the concrete which contains some form of calcium carbonate, which through some form of reaction to light or water once exposed will quickly react and fill the hole with calcium carbonate.
This can be undertaken either through certain types of bacteria that produce calcium carbonate, the use of small capsules that contain calcium carbonate hydroxide that activates once exposed to the elements, or chemical capsules or pipes that contain glue or epoxy resin to fill the hole.
The fundamental process has been found to work through research, although a lot more research is required to perfect the process and ensure that a crack is entirely filled via the process.
Living Building Materials
In 2020, a study undertaken at the University of Colorado highlighted how bacteria could be used in combination with sand, nutrients and gelatin to create gel bricks thanks to how the bacteria, Synechococcus, creates calcium carbonate crystals.
Once it becomes a gel it can then be dried to form bricks, with the team comparing the construction process to concrete.
However, at present, the mixture is far more reminiscent of mortar, the weaker material used to glue bricks together, and is not as strong as standard bricks nor strong enough to be used in construction at present.
This theoretically could be used to grow building materials in the future, but the process needs to be refined, and it is somewhat of a stretch to describe it as “growing concrete”.
The world of living building materials is a fascinating part of bioengineering, and time will tell what the building materials of the future will be made of.