
Instant stone (just add water) (2018) - exolymph
https://rootsofprogress.org/instant-stone-just-add-water
======
jbotz
Nice article, and this is certainly a topic that everyone should know a little
about seeing how fundamental cement is to our civilization. But it left out
something very important at the end there... steel reinforced concrete is
fantastic stuff of course, but it also comes with a drawback that is about to
cost us very dearly; it doesn't last very long. All of our magnificent bridges
and fantastic architecture come with a built-in expiration date because the
steel inside them is rusting. That expiration date is somewhere between 50 and
150 years, and for a lot of our infrastructure it's coming due.

Concrete made from portland cement is waterproof but it isn't moisture proof,
nor airtight. It breathes just enough that the oxidation of steel isn't
completely stopped. And when the rebar rusts it expands, which causes the
concrete to crack, letting more moisture and air in, causting the rebar to
rust faster.

There are solutions to this problem, such as using rebars made from materials
less susceptible to rust (stainless steel or even carbon fiber), but for the
most part they are either a lot more expensive or nowhere nearly as strong.
And there is susprisingly little research into this considering how important
it seems... our civilization isn't very good at committing resources to things
that have payoffs longer than 50 years, so everyone continues to use plain old
steel as rebar in their constructions. Meanwhile, the Roman pantheon remains
standing, perhaps another couple of thousand years?

~~~
gnode
Basalt fibre reinforced concrete looks promising. The tensile strength is
greater than steel rebar, and inexpensive when compared to carbon fibre. The
environmental impact is much lower, as it's a melting process similar to
fibreglass production, rather than smelting.

I get the impression that the continued use of steel rebar is less because
there aren't superior technical solutions, but because there are significant
regulatory, training and qualification hurdles. Use of non-steel rebars seems
to complicate projects, and is only justifiable in special situations. Steel
is usually adequate when appropriate anti-corrosion measures are taken (such
as coating the rebar in epoxy).

~~~
MertsA
>such as coating the rebar in epoxy

Actually epoxy coated rebar has pretty major debonding issues in practice. If
the epoxy coating was continuous then sure, but realistically during bending,
cutting, tying, etc you're basically guaranteed to introduce scratches through
that thin epoxy layer and once that steel starts rusting it'll tend to spread
under the surface causing more cracks in the epoxy and allowing more
corrosion.

The abstract of this report shows that epoxy coated rebar performs rather
poorly.
[http://www.virginiadot.org/vtrc/main/online_reports/pdf/00-r...](http://www.virginiadot.org/vtrc/main/online_reports/pdf/00-r16%20.pdf)

>Adhesion loss of the epoxy coating to the steel surface was detected in all
but one deck that was 4 years old and older. The epoxy coatings were debonding
from the reinforcing bars. Whereas a bonded coating can be expected to protect
the steel, a debonded coating allows chlorides, moisture, and oxygen to reach
the steel and initiate a rapid corrosion mechanism. Reinforcing bars in
various stages of adhesion loss showed visible signs of a corrosion process
underneath the coating, suggesting that ECR will provide little or no
additional service life for concrete bridge decks in comparison to bare steel.
Other systems that will provide longer protection against chloride-induced
corrosion of the reinforcing steel with a higher degree of reliability should
be considered.

------
ChuckMcM
The follow up from this year (2019) [https://rootsofprogress.org/cement-
redux](https://rootsofprogress.org/cement-redux) is even more interesting. It
also mentions the DARPA effort to re-discover the formula for Roman maritime
cement which gets stronger in sea water rather than erodes in sea water.

If we can figure that one out we could make concrete hulls for ocean going
ships that would last many lifetimes.

~~~
samstave
I thought I read recently that the 'secret' to Roman Cement - was that they
were using volcanic ash, which changed the composition and resulted in a
better ingredient.

[https://www.nature.com/news/seawater-is-the-secret-to-
long-l...](https://www.nature.com/news/seawater-is-the-secret-to-long-lasting-
roman-concrete-1.22231)

~~~
ChuckMcM
Yes and no. The linked article explains that the 'secret' was ash from Mt
Vesuvius which added silicates. But the Romans had _another_ cement called
"Maritime Cement" which is mentioned in the second article (the follow up
article that I linked) which says,

 _" There does seem to be one particular application in which the Romans had a
formula we would like to rediscover: maritime concrete, exposed to seawater.
Normally, concrete in a pier or harbor erodes over time, both due to the salts
and other minerals in the seawater, and due to the abrasion of sand and silt.
However, some Roman marine structures have survived for 2,000 years.
Geologists studying Roman concrete have recently discovered (2017) that the
particular concrete formula used in those structures has a beneficial
interaction with seawater, creating new crystals within the cementing matrix
that actually increase strength. DARPA just announced that “Unlocking the
Secrets of Roman Concrete” is one of many topics for exploration under a
research awards program."_

~~~
amluto
Is it substantially better than modern concrete with seawater-proof
reinforcement? Stainless steel rebar, fiberglass rebar, and basalt rebar all
exist. The latter sounds quite promising if you believe its manufacturers’
claims.

(A major cause of failure of concrete near or in the sea is that the rebar
corrodes and expands, cause the concrete to break.)

~~~
ChuckMcM
Yes it is substantially better because it _grows_ in sea water. Which is to
say that it is self healing with respect to erosion. They give examples of
roman maritime concrete that is over 2000 years old and still functional. No
existing concrete does this (hence the DARPA call for research topics).

It is also why a concrete hulled boat using this stuff would not suffer hull
erosion like the existing cement fleet did during world war II and afterwards.

It isn't clear to me (but I've not found a good paper on Roman "maritime"
concrete either :-)) how it interacts with barnacles and other marine life.

------
erikpukinskis
Cement is cool. But you know what’s _really cool_?

Rammed earth.

It won’t crack like cement. It doesn’t require any special chemicals like
cement. Doesn’t need to be shipped anywhere...

At least not... as much of it. If you built a rammed earth structure you will
use a little cement actually. So everything that’s in cement, there will be a
little of it in your rammed earth home.

But mostly you’ll just use readily available local-ish materials. Now for the
benefits:

\- Will last 1000 years

\- Perfectly finished on the inside and outside with no fussy carpentry,
mudding, or painting

\- Thermal mass for free

\- Load bearing

\- Sheds water

\- Breathable

\- Insects won’t bother

\- Basically as strong as stone

\- Stunningly beautiful

\- Largely free of odd vapors and perfumes

I am a fan.

There are downsides. It’s not right for every application. It is _labor
intensive_. And it’s skilled labor bordering on artistry. But from my
research, it’s the ultimate wall there is.

~~~
jliptzin
I am in the planning stages of building a 25 foot obelisk on my property. I
was planning to use concrete and hadn't heard of rammed earth. Is rammed earth
an appropriate material for my project?

(Everything thinks I am joking about this but I am 100% serious)

~~~
swebs
Does it have some sort of purpose? Personally I would choose granite since I
don't want people to think my god is poor.

~~~
carapace
GP could use Wallington's technique and place a monolith:
[https://en.wikipedia.org/wiki/Wally_Wallington](https://en.wikipedia.org/wiki/Wally_Wallington)

------
riffraff
I never realized that "quick" means "alive" in quicklime, quicksilver.

It's interesting because I now see the same pattern is used in old italian
(mercury is "mercurio" but also "argento vivo", living silver, and calcium
oxide is "ossido di calcio" but also "calce viva", living lime).

As far as I understand, in hungarian ("fürge ezüst" -> "lively silver") and
german ("quecksilber" -> quicksilver) the same pattern exists for mercury,
though I didn't find the calcium carbonate equivalent.

I imagine there is some shared (alchemic?) tradition there, and I wonder what
other "alive" things exist.

~~~
speedbird
Also quicken - current use is "to make faster" but older form is "to come
alive"

~~~
harimau777
Quickening is also the point in pregnancy when the women can first feel the
infant's movements.

------
litoE
One reason that steel and concrete work so well together, with concrete
handling the compression loads and steel handling the traction loads, is that
they have a very similar thermal expansion coefficient. Thus, when the
temperature changes both components expand or contract at the same rate. Just
think of what would happen if they didn't.

------
jstsch
Nice article. Cement’s climate footprint is really big though, so we should be
using it in construction much less than we’re doing now. Glulam is the future.

~~~
twothamendment
Gluelam and CLT (cross laminated timber) could be used in so many places.

I live in an area where trees are like weeds, but the logging industry is
nearly dead because "we can't cut down the trees!!!".

So, environmentalists, which will it be? Concrete or trees? We have to build
with something...

~~~
XorNot
Plantation grown timber is a _very_ different proposition compared to logging
an old-growth forest.

Frankly you don't have as many trees around you as you think you do (and
you're probably a lot more dependent on them then you realize since local
forests are usually performing an important ground support function in
preventing hillsides washing away in the rain).

No environmentalist is opposing sustainable plantation timber operations, and
there's plenty of those going on everywhere.

~~~
maxerickson
If they live in the US they probably don't live near much old growth forest.

For instance, nearly all of Michigan was logged. Someone driving through the
state might not think so, but most of the trees here grew back after that.

~~~
klyrs
OTOH a disturbing amount of oldgrowth is being harvested in Canada to this day

------
RRWagner
"cement" is just the beginning of a more fascinating journey into the work of
Joseph Davidovits. I encourage anyone interested in this to read his books,
including "The Pyramids: An Enigma Solved" and "Why the Pharaohs Built the
Pyramids with Fake Stones". This isn't a crank theory. He has patents on the
process, which ironically, could have been declined on the basis of "prior
art", but since no one believed him, he has the patents. One can buy kits of
everything needed to mix up personal batches and independently confirm his
chemistry. [https://www.amazon.com/Pharaohs-Built-Pyramids-Fake-
Stones/d...](https://www.amazon.com/Pharaohs-Built-Pyramids-Fake-
Stones/dp/2951482043/) [https://www.amazon.com/Pyramids-Enigma-Solved-Joseph-
Davidov...](https://www.amazon.com/Pyramids-Enigma-Solved-Joseph-
Davidovits/dp/0880295554) [https://www.davidovits.info/book-why-the-pharaohs-
built-the-...](https://www.davidovits.info/book-why-the-pharaohs-built-the-
pyramids-with-fake-stones/)

~~~
jedimastert
I do love the theory, and the elevator pitch makes a lot of sense.
Unfortuantely I don't have the bandwidth to really dive into it like I'd like
to, but I did find what seems to be a paper disputing his claims[0]. Below is
the abstract (emphasis my own):

> Since 1974 Joseph Davidovits, a French concrete chemist, has been proposing
> that the pyramids and temples of Old Kingdom Egypt were built of geopolymer
> “concrete” poured into molds, rather than quarried blocks of limestone. We
> use geological evidence and engineering principles to demonstrate the flaws
> in this daring hypothesis. Pyramid and temple blocks show sedimentary
> bedding, burrows, and optical and SEM-scale properties characteristic of
> normal microporous limestones, and they are cut by tectonic fractures. Block
> dimensions and shapes are not likely to be the product of pouring into
> wooden molds, and some blocks show quarrying marks. _It is not easy to give
> a geological education to a brilliant and determined chemist._

[0]:
[https://www.tandfonline.com/doi/abs/10.5408/0022-1368-40.1.2...](https://www.tandfonline.com/doi/abs/10.5408/0022-1368-40.1.25?journalCode=ujge19&)

------
cryptozeus
Also interesting thread on concrete in HN
[https://news.ycombinator.com/item?id=18651154](https://news.ycombinator.com/item?id=18651154)

------
_Codemonkeyism
Also
[https://en.wikipedia.org/wiki/Shibam_Hadramawt](https://en.wikipedia.org/wiki/Shibam_Hadramawt)

------
lurquer
Of interest are speculations regarding how cement was discovered in the first
place.

That is, why would one make a kiln to heat the rock? (A mere campfire won't
cut it... doesn't get hot enough.) Some speculate it could have been a
lightening strike on a slab of rock, investigated by an early human who
discovered the resulting crumbly powder re-solidified with water. But, this
seems very unlikely. Big mystery.

~~~
kragen
Calcite calcines to quicklime at 850°, which is red-orange. Mere campfires
commonly reach yellow heat, which is over 1000°, and have often been used to
cook shellfish, whose shells are made of calcite and can calcine to quicklime.
So I suspect that the discovery of quicklime probably happened numerous times
in mere campfires during the first three million years of human history called
the Paleolithic. (There might have even been several independent nutcases who
decided to experiment with the stuff even after they saw what it did to
water.) Lime kilns, though not the same thing as campfires, were commonly
wood-fired, even into the 20th century.

In the Neolithic, the humans were firing pottery, which often requires
temperatures over 850°, depending on the clay body you're using. It isn't
clear whether lime kilns predate the Neolithic, but if they don't, pottery
kilns would have occasionally produced quicklime by accident until you figured
out that you can't temper your pots with shellfish (or calcite-containing
sand) if you're going to fire them over about 800°, which is not particularly
difficult. (Modern earthenware is usually fired over 1000°.) That would have
made the discovery of quicklime unavoidable, if it didn't happen earlier, and
of course potters must spend a great deal of time investigating the properties
of their materials and how they respond to firing.

------
rasengan0
TIL when civilization gone asunder, reading this felt like I can rebuild the
house

~~~
VBprogrammer
If that's something which interests you then you should read The Knowledge:
How to Rebuild our World from Scratch.

~~~
kragen
Not a reliable source.

~~~
jasoncrawford
Why not?

~~~
kragen
The author doesn't maintain an errata site, and it has potentially fatal
errata.

~~~
jasoncrawford
Such as?

~~~
kragen
I don't remember all of them, but one was that the dude left out the part of
the alcohol-distillation procedure where you dump the liquid that comes over
first, which contains most of the methanol. A lot of blues singers went blind
from someone skipping that step, and people have died from it, too.

In general, he doesn't provide adequate information about safety precautions.
The book is like an _Anarchist 's Cookbook_ for bootstrapping—anybody who
tries its recipes without further information is likely to end up dead. It
should be called _The Misinformation_.

The thing that got me was that when I told him that there were potentially
fatal errata and where to look to see if they were already known problems, he
said there was no public list; I should just take the time to write up the
problems without knowing whether he already knew about them or not, and there
was no way for readers to find out what errors had already been reported in
the version of the book they already had. I think that says more about his
attitude about accuracy than any particular error in any particular version of
the book.

