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Can We Live Without Concrete? (cnn.com)
A combination of cement, water and ground rock or sand, on the surface concrete might seem crushingly mundane. Yet it has defined construction in recent centuries and with it, in part, modernity. From a report: But do we need to re-evaluate our concrete habit for our sakes and the planet's? Production of cement is disastrous for our biosphere, while the degradation of many concrete buildings has some construction experts predicting a colossal headache in the future. There are myriad proposed solutions, such as changing the way we make concrete, creating sustainable alternatives or doing away with it altogether. But would we want to live in a world without concrete? And what would that world look like?
"We make more concrete than anything else, any other product, apart from clean water," says Paul Fennell, professor of clean energy at Imperial College London. One 2015 report estimates that each year approximately three tons of concrete are used for every person on Earth -- roughly, 22 billion tons. To put that in context, a recent study estimated that 8.3 billion metric tons of plastic have been produced, ever. Manufacturing cement, concrete's binding agent, is energy-intensive, Fennell says. Ordinary Portland cement -- the most common form in concrete -- is produced by baking lime in a kiln and emits approximately one ton of carbon dioxide for every ton of cement. Concrete production is responsible for approximately 5% of global man-made CO2 emissions, according to the World Business Council for Sustainable Development.
"We make more concrete than anything else, any other product, apart from clean water," says Paul Fennell, professor of clean energy at Imperial College London. One 2015 report estimates that each year approximately three tons of concrete are used for every person on Earth -- roughly, 22 billion tons. To put that in context, a recent study estimated that 8.3 billion metric tons of plastic have been produced, ever. Manufacturing cement, concrete's binding agent, is energy-intensive, Fennell says. Ordinary Portland cement -- the most common form in concrete -- is produced by baking lime in a kiln and emits approximately one ton of carbon dioxide for every ton of cement. Concrete production is responsible for approximately 5% of global man-made CO2 emissions, according to the World Business Council for Sustainable Development.
Yeah, nah.
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Ergo, humanity must not exist, since we could not have existed before concrete.
The truth is probably somewhere in the middle. Some of us could have existed, others not. To understand why, ask yourself: What was the human population before the invention of concrete, and what is the human population now? At least some of this additional carrying capacity probably arises from inventions that rely on concrete.
The crux of the article was Rammed Earth, which I think is a great replacement for concrete for certain applications (some load-bearing vertical walls mainly). Dirt cheap, clay & sand.
Some applications of concrete are frivolous and I think can be replaced. The reason is mostly cost and availability, and the current labor force is skilled with using it. The wall-facade material of choice before concrete, and before gypsum drywall, was Lime plaster. For wet or exterior applications I am in favor of using lime as it is less carbon-intensive than concrete and produces a beautiful lighting effect from birefringence (https://en.wikipedia.org/wiki/Birefringence), owing to the tiny calcite crystals that form when it cures back into limestone. See http://www.sapphireelmtravel.com/travel-journal/chefchaouen-morocco-blue-city for an example.
There's also benefits to the water vapor breathability of lime vs. concrete (which doesn't breathe, unless it's cracked).
Producing Lime plaster is less carbon-intensive than cement as it requires lower temperatures, and the CO2 driven off by the limestone during calcining (which happens in Ordinary Portland Cement production as well) is mostly re-absorbed by the slaked lime as it cures back into limestone (leaving the net CO2 footprint coming from the fuel used to calcine the lime, if coal or natural gas or wood is used, although perhaps decades into the future someone comes up with a nuclear-fueled kiln, electric or high temp gas or whatever).
The big downside to lime plaster is the time it takes to cure, and what that does for timelines and labor costs. It usually requires multiple thin coats (with a week or more between =3/8 inch coats - need time for CO2 to reabsorb as carbonic acid which also requires the material be damp, but not covered in water) which blows up the labor costs.
https://johnspeweik.com/2011/10/27/the-lime-cycle/
The upside to using lime plaster is there's a wealth of historical information on what to do with it... much of the "bling" of the pre-1800's architecture can be traced to the use of lime or limestone.
E.g. the Moroccan process of Tadelakt - https://en.wikipedia.org/wiki/Tadelakt
Venetian plaster - https://www.architecturaldigest.com/story/venetian-plaster-trend-guide
the real at&t mix
Sorry, forgot the link:
https://phys.org/news/2012-04-...
The lime emits CO2 as CaCO3 converts to CaO. It does not absorb back into the material in the use-case of Portland Cement.
Lime plaster, which I posted about further down, DOES bring that CO2 back into the material (as it cures by Ca(OH)2 converting back to CaCO3+H2O with the introduction of carbonic acid, i.e. CO2 dissolved in a thin film of water).
the real at&t mix
Turns out there is a product called 'Hempcrete' but its better used for insulation than the kinds of things we would use concrete for. Hempcrete will float in a bucket of water
source: http://www.americanlimetechnol...
"Concrete is as good as stone, and you see how long ancient Greek, Roman, and Egyptian stone structures have stood. "
The Romans built almost everything with concrete, also the 'stone' structures you mean. The stone was usually only a thin outer shell to contain the poured concrete.
Also their concrete was (and is) much more resilient, it didn't crack as easily as our Portland variant. Portland cement wouldn't last for millennia, it sometimes doesn't take decades to make it fail.
"Recently, it has been found that it materially differs in several ways from modern concrete which is based on Portland cement. Roman concrete is durable due to its incorporation of volcanic ash, which prevents cracks from spreading."
https://en.wikipedia.org/wiki/...
Believe it or not it has to do with sand.
Sand with sharp edges.
Sand from the desert is round and is not good for cement.
So stop worrying about the CO2, energy, etc needed to make cement. we are running out of sand.
https://science.slashdot.org/s...
http://www.spiegel.de/internat...
https://www.npr.org/2017/07/21...
IOW: we are fsked. Roads, buildings, bridges, etc will have to be built with something else and nobody cares to even worry.
Obama's legacy: (N)othing (S)ecure (A)nywhere and (T)error (S)imulation (A)dministration
Captain Pedantic gets two demerits. The source of the CO2 production in the production of concrete IS from that ingredient called "cement". Sand, aggregate and water contribute nothing to CO2 release.
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