Mysterious lime clasts, dismissed as defects, turn out to serve a useful purpose:
The famous Pantheon in Rome boasts the world's largest unreinforced concrete dome—an architectural marvel that has endured for millennia, thanks to the incredible durability of ancient Roman concrete. For decades, scientists have been trying to determine precisely what makes the material so durable. A new analysis of samples taken from the concrete walls of the Privernum archaeological site near Rome has yielded insights into those elusive manufacturing secrets. It seems the Romans employed "hot mixing" with quicklime, among other strategies, that gave the material self-healing functionality, according to a new paper published in the journal Science Advances.
[...] In his treatise De architectura (circa 30 CE), the Roman architect and engineer Vitruvius wrote about how to build concrete walls for funerary structures that could endure for a long time without falling into ruins. He recommended the walls be at least two feet thick, made of either "squared red stone or of brick or lava laid in courses." The brick or volcanic rock aggregate should be bound with mortar composed of hydrated lime and porous fragments of glass and crystals from volcanic eruptions (known as volcanic tephra).
[...] For this latest study, Masic wanted to take a closer look at strange white mineral chunks known as "lime clasts," which others had largely dismissed as resulting from subpar raw materials or poor mixing. "The idea that the presence of these lime clasts was simply attributed to low quality control always bothered me," said Masic. "If the Romans put so much effort into making an outstanding construction material, following all of the detailed recipes that had been optimized over the course of many centuries, why would they put so little effort into ensuring the production of a well-mixed final product? There has to be more to this story."
It was believed that the Romans combined water with lime to make a highly chemically reactive paste (slaking), but this wouldn't explain the lime clasts. Masic thought they might have used the even more reactive quicklime (possibly in combination with slaked lime), and his suspicion was born out by the lab's analysis with chemical mapping and multi-scale imaging tools. The clasts were different forms of calcium carbonate, and spectroscopic analysis showed those clasts had formed at extremely high temperatures—aka hot mixing.
[...] It also seems to impart self-healing capabilities. Per Masic, when cracks begin to form in the concrete, they are more likely to move through the lime clasts. The clasts can then react with water, producing a solution saturated with calcium. That solution can either recrystallize as calcium carbonate to fill the cracks or react with the pozzolanic components to strengthen the composite material.
Masic et al. found evidence of calcite-filled cracks in other samples of Roman concrete, supporting their hypothesis. They also created concrete samples in the lab with a hot mixing process, using ancient and modern recipes, then deliberately cracked the samples and ran water through them. They found that the cracks in the samples made with hot-mixed quicklime healed completely within two weeks, while the cracks never healed in the samples without quicklime.
Journal Reference:
Linda M. Seymour, Janille Maragh, Paolo Sabatini, et al., Hot mixing: Mechanistic insights into the durability of ancient Roman concrete, Sci Adv, 9, 2023. DOI: 10.1126/sciadv.add1602
(Score: 4, Insightful) by JoeMerchant on Monday January 09, @06:14PM (1 child)
"Walls at least two feet thick" - well, yeah, that's sensible, if expensive, but if you want your slaves to build a long lasting wall, make it thick.
"bound with mortar composed of hydrated lime and porous fragments of glass and crystals from volcanic eruptions (known as volcanic tephra)." - yes, that's the specification, and history shows it works well, but did the Romans even know that it worked better than an aggregate of sand, stones and thoroughly mixed hydrated lime (modern concrete)? Or, was this like the piss of a readheaded virgin on hot iron making the strongest swords in the 12th century AD? They knew it worked, but obviously lacked some of the more detailed metallurgical and chemical understanding as to why?
With modern methods, precise encapsulation and subsequent availability of unhydrated lime to the final aggregate should produce some very durable structures, and all kinds of debate in the accelerated life testing literature.
Україна досі не є частиною Росії Слава Україні🌻 https://news.stanford.edu/2023/02/17/will-russia-ukraine-war-end
(Score: 0) by Anonymous Coward on Monday January 09, @07:52PM
I suspect it was alien technology passed down from, well, aliens I guess. Couldn't be those dumb primitives knew any better.
(Score: 3, Interesting) by krishnoid on Monday January 09, @08:09PM (8 children)
I'm kind of happy, that with people complaining about everything awful going on in the world, we're still getting new research insights into long-since-discovered stuff, both natural and human-processed.
The Internet makes this sort of information globally interchangeable, vettable, discussible, and low-cost, as well as providing the Pandora's box of social media and electronic addiction. But it can also be counted on for the reliable infrastructure responsible [youtu.be] for providing it all.
(Score: 2, Insightful) by Anonymous Coward on Monday January 09, @09:08PM (1 child)
I see it as a constant battle between engineers/scientists working out ways to make better things...and MBA's racing to the bottom, doing their best to ignore all the possible improvements in search of the lowest cost, to increase sales or even monopolize a market.
(Score: 3, Insightful) by krishnoid on Monday January 09, @09:22PM
Really makes you wonder [youtu.be] who's looking out for the future of humanity, if anyone.
(Score: 2) by bzipitidoo on Tuesday January 10, @01:51AM (5 children)
> The Internet makes this sort of information globally interchangeable, vettable, discussible, and low-cost
This is why I agree with a list that rated the Gutenberg Press as the #1 invention of the 2nd millennium. It really spread information, and information is extremely important. I have concluded that the Internet does the same thing as the press and more, and even faster, cheaper, larger, and all around better than print, and that therefore it will prove to be the most significant invention of our time. Some kinds of info that the Internet handles with ease are utterly impractical with print. Simply can't do video streaming, for instance. It is amazing how much the Internet has changed life in the past 30 years. It's tempting to think of transportation advancements as supreme, but the Internet has demonstrated that a great deal of transportation is actually unnecessary. Telecommuting beats the heck out of commuting, whether by horseback, train, combustion engine car, electric car, or jet. Trooping over to a library full of printed material is greatly inferior to online surfing for info, another strike against fast transport to and from a library. Wikipedia beats the stuffings out of print encyclopedias, able to contain far more info on many more subjects, and stay far more current.
(Score: 1, Interesting) by Anonymous Coward on Tuesday January 10, @08:48AM (3 children)
Without that it's less likely for us to postpone our extinction - we'd be stuck on Earth.
If the Internet can help produce and allocate the right talented indivduals into the appropriate places so that this advancement happens in time then that's great.
I suspect that cheap fossil fuels can be helpful for boot strapping to that tech level even if fossil fuels may not be required as much for later stages. So if we run out of fossil fuels before we achieve that step it could delay things significantly.
(Score: 1, Insightful) by Anonymous Coward on Tuesday January 10, @01:24PM (2 children)
If by significantly you mean forever, at least as far as humans are concerned
If we run out of fossil fuels before we develop alternatives we are going to have a post apocalyptic world where people fight to the death over scraps, a la Mad Max.
Once we fall that far it is over for hundreds of millions of years at least. Never mind gas and liquid fossil fuels, those fields will replenish themselves in a few centuries to a few millennia. We have mined out all the easy metals and all the easy coal. Without those there is no way to bootstrap another industrial revolution if we fall far enough to need one. The next civilisation to have a chance to get to space is going to be after the continents turn over.
(Score: 2) by Reziac on Wednesday January 11, @04:20PM (1 child)
I've looked at how merit is being displaced by "equity" and reached the exact same conclusion. Once everything is "equal" (which is to say, leveled) we will never again find the level of innovation and striving necessary to explore space. And I do mean never, because speciation seems to have uniformly reached evolutionary dead ends -- we aren't seeing another species emerge to rival human ability, and there's been plenty of time for that. (Spotted hyenas might have, before they lost the dewclaw and all chance for an opposable thumb.) Rather, every species sinks deeper and deeper into its evolved niche, losing generalist traits along the way. Humans are losing our generalist traits in another way, by killing off merit. Only a start-over cataclysm will change that.
And there is no Alkibiades to come back and save us from ourselves.
(Score: 0) by Anonymous Coward on Thursday January 12, @12:25AM
If you are trying to evolve general intelligence I think there are significant advantages with starting small. Any large animal is already well evolved into its niche. Octopi are interesting, but getting as far as fire would be a big step. They would need to become at least semi amphibious.
Raccoons are a distinct possibility. If you were directing it as a long term project, there are of course all the apes and monkeys, but then you are just basically re-evolving humans.
Really you need something that can evolve to manipulate tools. Bears are too settled, pandas are an evolutionary failure, any large herbivore is just going to eat grass and run from predators.
Squirrels are interesting. Quick, clever, agile, paws that could easily evolve to be better tool users, and small enough that many generations can pass quickly. Scale a squirrel up to be 3 foot tall (bipedal stance) and you've got between 30 and 60 times the cranial capacity. How smart would that be?
(Score: 2) by Freeman on Tuesday January 10, @02:29PM
Your local library, especially, if you're in a higher education environment. Pays a ton of money to vendors to supply access to databases that the average person likely doesn't know exist. Also, $50 per article access is insane, just get it for free from your Library.
Joshua 1:9 "Be strong and of a good courage; be not afraid, neither be thou dismayed: for the Lord thy God is with thee"