
With Fungi in the Mix, Concrete Can Fill Its Own Cracks - bryanrasmussen
https://www.smithsonianmag.com/innovation/with-fungi-in-mix-concrete-can-fill-its-own-cracks-180967911/?no-ist
======
fractallyte
Or perhaps we could go back to using lime[0], which has long been known to be
naturally self-healing[1], and has been used throughout history to build
structures that (literally) stand the test of time[3]. And let's not forget:
considerably less CO2 emissions during its lifetime[4].

[1]
[https://en.wikipedia.org/wiki/Lime_mortar](https://en.wikipedia.org/wiki/Lime_mortar)

[2] _Self-healing of lime based mortars: microscopy observations on case
studies_
[https://repository.tudelft.nl/islandora/object/uuid:ff226ad0...](https://repository.tudelft.nl/islandora/object/uuid:ff226ad0-ffb2-4b4c-bdb6-9881961bc7f1/datastream/OBJ)

[3]
[https://en.wikipedia.org/wiki/Lime_(material)#Roman_concrete](https://en.wikipedia.org/wiki/Lime_\(material\)#Roman_concrete)

[4] [http://ecolime.co.uk/c02-quick-facts/](http://ecolime.co.uk/c02-quick-
facts/)

~~~
nickbauman
I thought the secret of Roman concrete was the Tufa, a pyroclastic sand, which
was used, for instance, in the construction of the Port of Ostia. This civic
work has 2000 year old concrete that's intact and in direct content with the
sea water.

~~~
logfromblammo
I thought it was the use of pozzolana--glassy aluminosilicate volcanic ash--
along with lime. The Roman _marine_ concrete may also have an advantage from
being mixed with _seawater_. It gets stronger in saltwater. Portland cement
concrete with iron rebar gets weaker in seawater, because the rebar swells and
makes the concrete spall off.

Although it is true that sand from different geologic deposits can show vastly
different results when used in the same building product. Superior binder plus
superior aggregate could make superior concrete.

~~~
Gibbon1
I think there is a fair amount of interest in pozzolana type cements because
it's becoming apparent that portland cement + rebar has a finite life.

> sand from different geologic deposits can show vastly different results

That's the other bugaboo about portland cement, Aggregate expansion/alkali-
silica reaction/concrete cancer. They used the wrong type of aggregate and
dune sand in the old foundation of my house (rental not my problem unless I'm
in it during the next earthquake). So now it's crumbling.

Granted if you keep reinforced portland cement dry, it's fine. Otherwise
eventually it'll fail.

------
gjem97
I for one would love to see something like this happen, but I think ultimately
this will always be limited to niche applications.

A developer recently built a 20 story apartment building next to my office
window using entirely a reinforced concrete frame. I was incensed to find out
that because of "concrete cancer" [1], the lifespan of that building may be
less than 70 years. But the more I thought about it, the more I began to
believe that maybe the additional lifespan is not an asset. The building is
attractive today, but might not (probably won't) appeal to people 40 years
from now. Furthermore, buyers are going to want different things from their
homes (look at the popularity of open kitchens 40 years ago vs now). And I
began to realize that it would be quite difficult to design and build a
building that would be useful beyond 70 years from now.

Another way to look at it is that the marginal value of 10 years of longevity
is not that large out 80-90 years. I think you'd have a difficult time finding
a developer who would pay 10% extra to get a building that lasts 100 years
instead of 90.

This line of reasoning leads to an icky "planned obsolescence" approach, but I
think these are the economic realities.

[1] [http://www.remedial.com.au/structural-repairs/concrete-
cance...](http://www.remedial.com.au/structural-repairs/concrete-cancer)

~~~
acomjean
As someone who lives in a building that is 70 years old, I can tell you pipes
(brass?) only last about 70 years.. redoing piping in place is a major pain.
If the location wasn't so good I'd be gone long ago..

~~~
kragen
Pipes can last centuries or only years, depending on the material, the
temperature, and the solutes in the water — even without getting into cases
where the pipes actually break. Both lead and copper (which is more common
than brass!) can last centuries in cold water that isn't chemically
aggressive. Heck, in Boston a few years back, they dug up some _wood_ pipes
that were installed in the 1700s.

------
DiabloD3
I find it funny that one of the sub-plots of Wolfenstein: The New Order is
sabotaging Nazi super concrete using fungi implanted in the mix at the
factory.

------
misc213
The article glosses over how the spores could expect to respond during the
highly saturated setting phase. It is reasonable to assume they could cause
deformations or web-like weak points in new concrete by being too active well
before they are intended to be active. I think getting a predictable outcome
during setting is probably the challenge.

------
adamnemecek
I never understood why our isn't aerated concrete more popular in the US.its
lighter and insulates heat and noise so much better.

~~~
athenot
Insulation is not as easy to achieve once you consider structure framing in
poured concrete, and humidity load (AAC is very permeable to moisture).

[http://www.greenbuildingadvisor.com/blogs/dept/qa-
spotlight/...](http://www.greenbuildingadvisor.com/blogs/dept/qa-
spotlight/does-autoclaved-aerated-concrete-make-sense)

------
wand3r
There is a waterproofing product called xypex that coats concrete. When you
get it wet its crystalline structure grows to fill cracks. It sounds similar
to what the article talks about. It looks good as well so if youre building a
house consider using it instead of the black tar typically coating a
foundation.

------
jimnotgym
Article from 2017 on same subject
[https://www.technologyreview.com/s/608717/how-mushrooms-
coul...](https://www.technologyreview.com/s/608717/how-mushrooms-could-repair-
our-crumbling-infrastructure/)

Similar process with bacteria rather than fungus from 3 years ago
[http://www.cnn.com/2015/05/14/tech/bioconcrete-delft-
jonkers...](http://www.cnn.com/2015/05/14/tech/bioconcrete-delft-jonkers/)

------
userbinator
_As they grow, they’ll work as a catalyst within the calcium-rich conditions
of the concrete to promote precipitation of calcium carbonate crystals. These
mineral deposits can fill in the cracks._

Pure calcium carbonate is not as strong as concrete. It sounds like this will
just fill in cracks with weaker material, hiding them from inspection, which
would be even worse --- the strength of the material is degrading but not
visibly.

------
JoeAltmaier
Still just an idea; not ever been tried apparently.

