I was looking into doing some budget reno recently and remembered “starched hessian” - which was somewhat in favour during the great depression. I’ve used and seen examples of it that look great and it has the appearance of masonry - helped no doubt by the use of Portland cement in the paint. So recently I was revisiting cement based paints and found Latex Concrete which enhances and strengthens concrete’s properties. There is such a thing as Ultra High Performance Latex-Modified Concrete and it is applied to bridges among other things in the US. But I am more interested in the mediums use in alternative building.
The first vid is from the guru himself and the second is a practical use, and in both cases, rather than hessian (burlap) they use two layers of Fibreglass insect screen as the substrate.
Okay this whole story wasn’t sitting right with me, so I did more research.
It’s a myth that Roman concrete was better than modern concrete. Their structures seem long lasting for two reasons:
Survivorship Bias. We don’t see all the ones that didn’t last. Some of our stuff will happen to last that long too.
They didn’t put rebar in their concrete, and this is what causes modern concrete to fail. Eventually the rebar fails because moisture gets to it and it corrodes. However Romans didn’t build skyscrapers and freeway overpasses which you can’t do without rebar.
So no, there isn’t some secret ancient lost Roman recipe for magic concrete. That’s bullshit.
Aqueducts are not freeway overpasses and apartment blocks are not skyscrapers. My point remains that we build things they couldn’t because of rebar. As you say yourself, those were built from stone, structurally, using their concrete as we do stucco now. We build things with concrete that cannot be made brick or stone.
Didn’t the Romans also have concrete that could set under water - salt water? Also the pyramids were apparently not stepped, as now, but were flat sided - covered by some kind of geo-polymer. So, in ancient times some folks knew a thing or two about cementitious materials that seems to have been lost over time. I see that someone also created a geo-polymer using just beach sand and urine - and there may have been some other catalyst also. This kind of thing is important for when shelters must be built of whatever is available on the moon or Mars etc.
Here it is:
The pyramids used to be cased. The great Cheops pyra- mid was covered with outer casing white fine limestone blocks from Tura limestone quarry, only a few of these now remain at the pyramid’s base on the corners. The backing limestone blocks of Chephren pyramid was cov- ered and cased with fine limestone blocks, also the stone cap now remain on the top of the Chephren pyramid. The Mykerinos pyramid was covered and cased with granite facing blocks were quarried and imported from Aswan quarry, 1000 km from Cairo.
During the middle Ages, much of the pyramid’s outer facing blocks were fell sown because of the 1303 earthquake, Table 1. Many facing blocks were taken and reused for the buildings of many Coptic and Islamic monuments in Cairo city, revealing the Fossiliferous limestone backing blocks.
The roman recipe for concrete (opus caementicium) was hinted at in Vetruvius’s De architectura, but many of the more impressive examples date from hundreds of years later. The devil’s in the details, and if the details aren’t written down…
Potland cement is infamously carbon intensive. The Roman alternative relies on pozzolanic volcanic ash, which means that it doesn’t scale…
I think you probably have it right. It’s hard to imagine any kind of non-diamond foam having a compressive strength anywhere near traditional concrete.
Years ago I worked at a special effects house and learned about a special mixture that was used to make red fireplace-style bricks, except far lighter and weaker than real ones due to a foaming agent added during production. They looked/felt/sounded just like real bricks, and you could even get brick layers to build walls with them. (I don’t know what they used for mortar.) then you could smash cars or whatever through them easily for action scenes, or karate chop them, break them over a stuntman’s head, etc. That was a fun job.
I had thought strength was about half, so 2000 psi. That’s the preformed Euro stuff, anyway (it’s a siding, it’s an easement to structural concrete, it’s roof staging…go unjam the autoclave will you) and it’s not as if you’re going to end up without voids even with great ashing and mineral fill. Heavy enough for posts, nasty enough to make runoff and animal habitation happen at bad times.
At least the graphene is inflationary (as opposed to BTC.) Cleave graphite or keep proper giant flakes by condensing carbon onto coated copper and floating it off by turns, or even better get those nanoribbons constructed on the most common catalyst you can get away with. Then build a really really clicky keyboard?
Yes, and so does ours. Again, it’s a myth that concrete can’t set underwater. It sets just fine.
Yes they were. You can still see the smooth sides at the top of Khafre, and a little on Khufu. There are slope-cut blocks now missing. They may have also been coated in some sort of mortar, but I don’t know that detail.
We may not have their exact recipes, but that doesn’t mean there was anything magic about them that we can’t do (and do better today). We have great recipes for Lunarcrete already, to your example. We don’t need the Romans’ help with that.
It’s amazing how many myths persist about “Roman concrete” and how much people love the idea of magical lost ideas that will solve all our problems. The Argument From Antiquity fallacy is powerful indeed.
Edit: I take back the part about not knowing their recipe. We do. I should have known because we have plenty of examples of Roman concrete and have had an awfully long time to study it. So even the idea that their magic concrete recipe is “lost to us” is also false. I get fooled by all these myths too. A cynical person might suggest that all this is rooted in a persistent deep-seated unconscious belief in the superiority of “Western” culture that white people carry around. We’re so ready to believe the Greeks and Romans were so amazing at everything. I’m not sure I’m quite that cynical yet, but check back with me in a little while.
the romans were very smart, meanwhile the rest of the world had to rely on ancient aliens. could egyptians or incans really quarry all that stone and move it to construct pyramids? it’s all very obvious when you think about it.
With all that grain-storage, the Egyptians could brew a lot of beer, use it to pay the workers, and then use the urine to make more geo-polymer. It’s the circle of … piss.
Egyptian hieroglyphics and Incan Rope strings were comparatively inaccessible, at least at the time when these tropes were laid down. There are similar myths about Korean and Chinese lost aviation technologies. And we musn’t forget that the Mahabharata tells the tale of an nuclear war.
I suspect that the myth of lost technologies was useful in the development of the patent system.
That wasn’t grain storage. It was used to keep razor blades sharp.
While we are going about making cement tougher with esoteric substances we might just as well be using cellulosic materials to obtain an improved result at far cheaper cost. By that I mean straw and even bamboo - these also diminish the amount of cement needed by 10-30% for a stronger result.
You can also do stuff like mixed length carbon tubes and orient everything magnetically in the potential direction of stress to create plane resistant structures. If you can’t afford the mixed length carbon tubes and uhmwpe with a vectran/nomex later closest to the humans, charred bamboo and wood pulp definitely works but is substantially harder to magnetically orient. Don’t forget to magnetize the water first and wash your aggregate with magnetized water.
This. Modern concrete is several times stronger, and fails because we add steel rebar that can corrode. Note: it is possible, and some companies are working on it but it’s more expensive, to use composites like glass or carbon fiber instead of steel as rebar, which could make a big difference to lifetime.
Also: Roman concrete took over six months to harden, and continued hardening slowly over the course of years and decades. That was fine when it was the best option around and the world didn’t change much from year to year anyway, but it doesn’t really make sense nowadays. “We just finished pouring the foundation, we’ll be ready to start construction in… ten years.” Good luck with that.
