Something I found really interesting in the article that I hadn't heard about before was self-reinforcing concrete:
quote:Today's concrete buildings have skeletons of steel, but Moeller said that could become obsolete with the development of a recently invented self-reinforcing concrete, though that may be many years off.
The Lafarge Group, a French firm that says it is the world's largest producer of concrete, sponsored the exhibit and is showing off a recent variety called "Ductal" that does not need steel reinforcement. The exhibit shows how a light rail terminal has been built in Calgary, Alberta, almost entirely of Ductal, with concrete arches spanning 20 feet and the concrete only a quarter-inch thick.
How cool is that?
Could any of our engineers talk more about this stuff? It sounds pretty fantastic.
Posts: 16059 | Registered: Aug 2000
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A random friend whose dad was an engineer of some sort told me that the Romans didn't build with concrete because it only lasts a hundred years. Is this valid? Is all of our concrete construction a lot less permanent than we thought? Or have they re-formulated to address that?
Posts: 8504 | Registered: Aug 1999
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Well I'm not a civil and any of them can jump in to contradict me.
The applications are very cool. But I predict it will be quite a while before they become commonplace simply because the current materials work so well and are so much cheaper. Archietects will likely be the ones specifying it for beauty and the civil engineers will whine because it is more difficult to work with. I doubt it will be going into bridges anytime soon because, no one is willing to risk unproven materials in something that deals with public lives on a daily basis.
If they can actually prove that this new stuff is as good as the 50-100 year concrete that they use in roads, then it might catch on. But civil engineering as a whole is a bit of a fuddy duddy profession when it comes to change. This is because they have to be. Lives are at risk.
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Annie, I'm not sure specifically about your question. The 50-100 year concrete that I am referring to is in use in highways which will wear out due to freeze thaw cycles and simply the heavy amount of traffic the interstates experience.
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Romon concrete and modern day concrete are two very different things. And AJ is right, we're total stick in the muds, hopeuly that'll comfort you next time you drive over a bridge.
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I think it was one of those small-town self-righteous type of "facts." You know - the things that people say to prove that the experts are idiots and everything's going to pot.
Posts: 8504 | Registered: Aug 1999
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That translucent concrete is pretty cool. Although it's hard to think of lots of practical uses for it beyond a nice design element.
Posts: 5957 | Registered: Oct 2001
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Hmmm, well, that's not really a new concept, it just appears that using glass as the reinforcement fiber is new. I think there are probably even better materials that could be used in this application. Oh, and if steel prices continue to rise like they have been recently, then I think we'll be seeing a lot more research and use of this particular material. And yes, we civil engineers don't like to do anything that hasn't been tried and true for decades. And since I work for the government, it's twice as bad. Posts: 609 | Registered: Apr 2003
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Name me a liquid that isn't water based. really anything you use would be water with something in it, and then the water would be the part that did the work and the rest would just come out of solution. And no, Mercury would not work for makinf concrete.
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Well, I'm looking for another chemical to act as an oxydizer, for where water may be a rare commodity.
Posts: 1843 | Registered: Aug 2003
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There are so many liquids that aren't water I'd really like to smack you hobbes However I don't think ethanol will work for portland cement, though it can work quite well for engineering tests.
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Stupid civils that have forgotten 4th grade science.
Solid, Liquid, Gas. Those are your basic choices. There are LOADS of things that are non-water-based liquids at room temperature. Water just happens to be the most abundant one on this planet. There are some interesting other plasma and gel states, but those are your exceptions.
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AJ, there's not that many liquids that aren't water based, oil is the most prominant, most others are almost never seen by the average person. And most of those are based on either oil or water...
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Annie concrete gets stronger with time, I'm not sure if the hoover dam has solidified yet and actually reached full strength. And it was designed NOT to wear out, roads are different than dams as far as wear and tear goes.
Hobbes "oil" is a very generic kind of liquid. your corn oil is different from your soybean oil. They are chemically different liquids.
Alcohol (grain) is an extremely common liquid. THere are other alcohols like isopropyl alcohol that are different as well. There are all kinds of interesting solvets used in household cleaning products and paint thinners. They are so ubiquitous you simply don't notice them.
And glass is technically a liquid if we want to get creative.
Iodine is not only a pure element but liquid at room temperature. (Actually I lied. Iodine is a solid at room temperature though it has a low melting point, bromine is a liquid)
And yes, alchool is different, and the actual full chemical compounds of oils are different, but the thing that makes them an oil is always a same, and it's the part that makes them liquid. And I would use the actual name and/ chemical forumal for it except I haven't taken chemistry in a really long time. Not to say I wasn't just making a quick, not thought-out joke in my first post, but now I'm having fun. Hope you don't mind...
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Ohh, and I'm pretty sure the Hoover Dam is soldified, I think it wouldn't be except that the way they made it was dividing it into lots of small cubic pieces, and that allowed it to set a lot, lot faster.
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This is actually really interesting. You could have never told me that I would find a discussion on concrete interesting. Thanks. Posts: 8504 | Registered: Aug 1999
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Hobbes don't talk about what you don't know anything about. It's making you look dumber and dumber.
and I said gLass not "gas"
liquids and gases both subscribe to the same functional fluid mechanics laws though the Reynolds numbers and the Nusselt numbers are drastically different.
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Well, there's always bromine. I think it might give the engineers ugly burns even if it worked, though...
Posts: 1114 | Registered: Mar 2004
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Ok I'm supposed to be finishing work. But, I called Steve. Steve asked me why Happy Camper wasn't laying the smack down.
They make Latex based concrete that doesn't have water in it. And the Hoover Dam while at 98% ish strength is still curing and giving off heat, and will be for like another 150 years.
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It's because I don't give a rats posterior about concrete. And about concrete being something other than a solid, well, it may technically be a suspension. But I guess it really depends on how much liquid has to be present. I'm not a chemist, darn it, I'm a geotechnical engineer. Ask me about clay mineralogy and I'd be able to tell you more about the chemistry.
Posts: 609 | Registered: Apr 2003
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For quick curing on busy highways. I think in some cases it may cure stronger too. Steve says the stuff is set in like 15 minutes and it is a pain to get off shoes.
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I know about steel and a bit about aluminum, but not much at all about cement or concrete. Only that without reinforcement it's great in compression but not at all good in tension.
And Hobbes, yeah, give it up! Lots of liquids are not water or oil.
I think the Romans used a lot of stone in their roads and walls and aquaducts. Stone lasts a whole lot longer than concrete or cement. Not sure about the mortar used to stick them together. The pyramids are just a good fit, neh? I don't know if they used any mortar in them at all, but rather trimmed the blocks until they matched up perfectly, then let gravity and friction do the rest. Of course, a pyramid is not something that has to have much tensile strength anywhere. There are only a few small chambers inside, I guess.
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AJ, do you really do much work with pure ethanol? I've never worked in a commercial laboratory, but both in the classes I took in college and in the high school labs I teach, we always use solutions of ethanol and water. Posts: 32919 | Registered: Mar 2003
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I just saw the Modern Marvels on the History Channel a few weeks ago, and they had a whole show on the Hoover Dam. It was really fascinating.
Both of you are right about the Dam; it did cool much quicker than it would have otherwise, because of the cooling system that runs through the whole Dam. They compartmentalized the structure and ran pipes carrying water through it. Otherwise they could have never made it from concrete, as it would have never cured.
However, it is still curing, and will be for somewhere between the next 130-160 years. That means it will be gaining in strength.
Also, the Dam is constructed to be under compression the whole time, not in tension, so we don't have to worry about it falling apart anytime soon, barring outside influences (i.e. terrorism).
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And AJ is right, we're total stick in the muds, hopeuly that'll comfort you next time you drive over a bridge. ![[Cool]](cool.gif)
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However I don't think ethanol will work for portland cement, though it can work quite well for engineering tests.![[Evil]](graemlins/evil.gif)
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