11 ms·
Instant stone (just add water) (2018)
- jstsch 7y agoNice 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.
- notelonmusk 7y agohttps://news.ycombinator.com/item?id=21438792 https://news.ycombinator.com/item?id=21438792
- rapnie 7y agoAlso see Sand Wars documentary (recently aired on Al Jazeera) https://en.wikipedia.org/wiki/Sand_Wars https://en.wikipedia.org/wiki/Sand_Wars
- twothamendment 7y agoGluelam 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 7y agoPlantation 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 7y agoIf 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 7y agoOTOH a disturbing amount of oldgrowth is being harvested in Canada to this day
- twothamendment 7y agoFrankly, you shouldn't assume you know how many trees are around me. Plantation grown and old growth are very different. Just because it is a forest doesn't mean it is old growth. I have a lot of trees and the State land next to me has even more that need thinned. I've thinned out my land for better forest health, better wildlife habitat and to reduce fire danger. The State would do well to do the same, but I is very hard to log anything but private land around here. What happened to my logs? They went to a mill and some for pulp. They weren't old growth, that was gone long ago, but new products like CLT can make use of smaller trees. Plantations are great, but this whole county grows trees like crazy. It isn't hard to look around and find something that can be logged in a response way, but getting approval is near impossible.
- XorNot 7y agoAn industrial logging operation fells and transports about 4 trees an hour. Let's assume about 5 productive hours in a day which is on the conservative side. So 20 trees per day. 100 per week. 1200 every 3 months. Taking a reasonably dense plantation size (which we can assume is close to optimal these days) we get 620 trees per acre (https://www.forest2market.com/blog/how-many-tons-of-wood-are-on-an-acre-of-land https://www.forest2market.com/blog/how-many-tons-of-wood-are...). So a single commercial logging operation is going to be able to clear cut 2 acres of dense forest every 3 months - which will then be just gone and not coming back with any type of biodiversity or wild life for at least 10 years probably longer if ever since we're not talking plantation growth here. You don't have as many trees as you think.
- jasoncrawford 7y agoHow does engineered wood do on strength and fire resistance? Would appreciate any unbiased comparisons vs. steel and concrete on those points
- twothamendment 7y agoThat is something I've wondered too. I imagine foundations, elevator shafts and other key parts might still be concrete. Buildings like this are fascinating: https://www.dezeen.com/2019/03/19/mjostarne-worlds-tallest-timber-tower-voll-arkitekter-norway/ https://www.dezeen.com/2019/03/19/mjostarne-worlds-tallest-t...
- rapnie 7y agoElevator shafts can be made with CLT too, like for the 9 storey Murray Grove in London built in 2009 http://waughthistleton.com/murray-grove/ http://waughthistleton.com/murray-grove/
- fiter 7y agoBurned wood acts as insulation for the unburned core so large timbers can have long fire ratings. The rule of thumb is 1.5" per hour. [0] I can’t comment on reinforced concrete, but structural steel requires protection to meet 1+ hour fire ratings. [0] https://www.nishkian.com/fire-rated-wood-construction/ https://www.nishkian.com/fire-rated-wood-construction/
- jedimastert 7y ago>Gluelam and CLT (cross laminated timber) I just looked up some picture. Is it just plywood and OSB with 2x4s? It seems so simple.
- dharma1 7y agoI think trees are a fantastic building material. If left to rot in nature, much of the carbon will slowly be released back to the atmosphere. The carbon sequestering abilities of trees also slow down after a certain age. Now this doesn't mean we should clear-cut old forests, or only have short-lived commercial forests. I think we should aim to have mostly natural forests with trees of different ages, up to hundreds of years, and use selective logging instead of clear cutting. Timber buildings can last hundreds of years. In such buildings, using timber is a great carbon sink. Interestingly, it's the glue that will deteriorate before timber does.
- mannykannot 7y agoI was surprised to see that the lime cycle itself is carbon-neutral, if I am reading it correctly. Is cement's footprint due to the energy required to make it? Or is the chemistry of portland cement not carbon-neutral?
- maxerickson 7y agoYeah, you gotta dig the stuff up, heat it to high temperatures and then ship it to where it is used.
- umvi 7y agoDig it with electric mining tools, heat it with a solar furnace, and ship it with electric trucks?
- catalogia 7y agoMaybe, but that's not how it's done today, and it's not the sort of thing you change overnight. Complicating matters is the fly ash component of modern concrete. Fly ash can replace 50% or more of the portland cement in concrete. Fly ash is a byproduct of burning coal. So when you replace the coal plants with solar arrays, you need to create even more portland cement than you would need to if you were burning coal (and using the subsequent fly ash in your concrete.)
- newnewpdro 7y agoI've read that kilns used to produce the clinker are often fueled by burning waste like used car tires. Wikipedia speaks to it a bit: https://en.wikipedia.org/wiki/Cement_kiln#Alternative_fuels https://en.wikipedia.org/wiki/Cement_kiln#Alternative_fuels
- jasoncrawford 7y agoBoth. See the followup here: https://rootsofprogress.org/cement-redux https://rootsofprogress.org/cement-redux
- kragen 7y ago
- rasengan0 7y agoTIL when civilization gone asunder, reading this felt like I can rebuild the house
- VBprogrammer 7y agoIf that's something which interests you then you should read The Knowledge: How to Rebuild our World from Scratch.
- 6gvONxR4sf7o 7y agoI'd love it if there were something like a 10 volume version of that.
- kragen 7y agoNot a reliable source.
- jasoncrawford 7y agoWhy not?
- VBprogrammer 7y agoBecause it's written as an entertaining book presumably. I don't know why anyone would even consider it reference material.
- kragen 7y agoThe author doesn't maintain an errata site, and it has potentially fatal errata.
- jasoncrawford 7y agoSuch as?
- 7y ago
- ChuckMcM 7y agoThe 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 7y agoI 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-lasting-roman-concrete-1.22231 https://www.nature.com/news/seawater-is-the-secret-to-long-l...
- phinnaeus 7y agoVery recently indeed, this is mentioned in the linked 2018 article. I assume there is some other secret sauce or it wouldn't be so secret.
- jasoncrawford 7y agoThe fact that they were using volcanic ash is nothing new. I mean, Vitruvius basically wrote down that it was volcanic ash. The specific chemistry of how the specific silicates interact with seawater and how that forms new compounds is a new discovery.
- RRWagner 7y agoThis is all explained in the books of Joseph Davidovits.
- ChuckMcM 7y agoYes 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."
- litoE 7y agoOne 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.
- cryptozeus 7y agoAlso interesting thread on concrete in HN https://news.ycombinator.com/item?id=18651154 https://news.ycombinator.com/item?id=18651154
- RRWagner 7y ago"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/dp/2951482043/ https://www.amazon.com/Pharaohs-Built-Pyramids-Fake-Stones/d... https://www.amazon.com/Pyramids-Enigma-Solved-Joseph-Davidovits/dp/0880295554 https://www.amazon.com/Pyramids-Enigma-Solved-Joseph-Davidov... https://www.davidovits.info/book-why-the-pharaohs-built-the-pyramids-with-fake-stones/ https://www.davidovits.info/book-why-the-pharaohs-built-the-...
- war1025 7y agoDon't know whether this is crank science or not, but it certainly seems like an intriguing theory.
- jedimastert 7y agoI 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/10.5408/0022-1368-40.1.25?journalCode=ujge19& https://www.tandfonline.com/doi/abs/10.5408/0022-1368-40.1.2...
- throwaway5752 7y ago
- erikpukinskis 7y agoCement 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.
- simonebrunozzi 7y agoI am not an expert, but why then most of the world has switched to cement, when cement is available at the right price?
- umvi 7y agoAccording to the wiki[1]: > Interest in rammed earth declined after World War II when the cost of modern construction materials decreased.[citation needed] Rammed earth was considered substandard, and still is opposed by many contractors, engineers, and tradesmen who are unfamiliar with earthen construction techniques.[7] The prevailing perception that such materials and techniques perform poorly in regions prone to earthquakes has prevented their use in much of the world.[citation needed] In Chile, for example, rammed earth edifices normally cannot be conventionally insured against damage or even be approved by the government.[citation needed] Lots of missing citations, but seems reasonable. I for one had never heard of this construction technique until today. [1] https://en.wikipedia.org/wiki/Rammed_earth https://en.wikipedia.org/wiki/Rammed_earth
- anon1m0us 7y agoDavid Suzuki profiled a rammed earth house on Vancouver Island that's a neat overview of it in action: https://www.youtube.com/watch?v=ra4Pldetd_M https://www.youtube.com/watch?v=ra4Pldetd_M
- PunksATawnyFill 7y agoThey didn't mention the Roman concrete that gets STRONGER with exposure to seawater: https://www.theguardian.com/science/2017/jul/04/why-roman-concrete-still-stands-strong-while-modern-version-decays https://www.theguardian.com/science/2017/jul/04/why-roman-co...
- riffraff 7y agoI 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.
- adwn 7y ago> [...] german ("quecksilber" -> quicksilver) [...] In German, there's also quicklebendig – meaning "lively", "very active" – compared to lebendig, which means "alive", "living". It's slowly becoming outdated, though.
- rimliu 7y agoIn Lithuanian mercury is "gyvsidabris" which is just portmanteau of "gyvasis sidabras"—literally "the living silver". Quicklime is different—"negesintos kalkes" which means "unextinguished lime".
- nickloewen 7y agoI didn't know other languages did this! In English "quicksand" seems to follow the same pattern.
- sudhirj 7y agoSeems common in old English as well, have seen bible references, though I can’t remember them now, and phrases like “the quick and the dead”.
- dredmorbius 7y agoThe Online Etymological Dictionary (DDG bang !etym) is great for this sort of inquiry: https://www.etymonline.com/word/quick https://www.etymonline.com/word/quick Similarly: quicklime, quicksilver, and quicksand.
- jbotz 7y agoNice 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?
- dtjohnnyb 7y agoHe talks a little bit about that in the (equally interesting) follow up post: https://rootsofprogress.org/cement-redux https://rootsofprogress.org/cement-redux
- gnode 7y agoBasalt 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).
- _Codemonkeyism 7y agoAlso https://en.wikipedia.org/wiki/Shibam_Hadramawt https://en.wikipedia.org/wiki/Shibam_Hadramawt
- lurquer 7y agoOf 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 7y agoCalcite 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.