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Conductive Concrete Offers Building Security
zdburke writes: "In a slightly different spin on the electromagnet-protected server room in Stephenson's Cryptonomicon, the folks at the National Research Council have developed concrete that conducts electricity, or 'percolates,' allowing it to serve as an electromagnetic shield. Current uses lean toward heated loading docks, non-freezing bridges, and grounding large-scale electrical equipment, but the counter-espionage idea is cool. The NYTimes has a brief story, and the folks at UN Omaha have some great pictures. It's not exactly new (it won a Popular Science prize in 1997) but it's still cool stuff."
Anyone remember the name of that psychologist that put dogs in a room with an electrified floor? I wonder if they'll start putting this stuff into jail cells and mental hospitals. You know, the prisoner/patient/subject mouths off they can give them a jolt. All in the name of science, of course.
So, does this mean that in the future, demolition companies could just HERF a building down instead of going inside and setting explosives?
Eve Fairbanks says I drive a hybrid!LOL
I wonder what kind of cell phone signal I would get in a conductive-concrete building? Probably next to none...
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"...but it's still cool stuff."
:)
Wouldn't "hot stuff" be more appropriate?
Is the cost per cubic foot much greater than standard concrete? If not, then I'd be interested in the implications for using it as a residential flooring substrate. Rather than going for a standard radiant heating system, would it be more efficient to employ this?
Pax Digitalia
I'm not a huge expert in the realm of physics (dammit, Jim, I'm a computer scientist!), but is this anything like a massive Faraday cage, which would prevent electromagnetic waves for entering and exiting?
:-)
I shudder to think of the day when we will work in protective buildings like these, keeping company secdrets safe from Van Eck phreakers and war drivers, but also keeping out the mellow, smooth sounds of Office Light Jazz 94.7.
Karma: Excellent Birds (mostly as a result of listening to Laurie Anderson)
Anyone remember the name of that psychologist that put dogs in a room with an electrified floor?
Pavlov. That was one of several experiments involving behaviour modification.
Eve Fairbanks says I drive a hybrid!LOL
So this stuff can conduct electricity, meaning it could generate a magnetic field, right? So you could theoretically generate a magnetic field to hold a concrete structure made from this stuff in the air. Does this mean that my goal of making a floating castle like all the bad guys in RPG video games have is finally within reach?
That unomaha site has one of the worst web designs I'ver ever seen. I guess it's not that important that scientist be designers, but readability would be a good thing to strive for. I don't need every paragraph to be a different color. Is this a side effect of too much exposure to conductive concrete?
Starsucks
I remember when a friend was recording a radio theatre show, the studio had chicken wire on all the walls (behind accoustic foam in most places) to minimize inteferrence from outside signals. You don't want your microphone cable picking up radio signals when recording a performance. This material could be ideal for construction in applications like that where you want to block out outside signals.
How about drywall transistors and logic-gate carpets?
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Now there is what every trucker needs for those cold winter days.
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Please study a little science before you post stories from similarly unclued "visionaries".
The most obvious use is heating.
But wouldn't it be cheaper and simpler to embed, say, a PVC 2-inch pipe in the concrete, and run warm water through that? Note that you can use this method with just about anything (dirt, asphalt, etc) and keep it from freezing.
If you want a method to directly heat it using electricity, run stainless steel pipe instead, and use it as a load.
I've frequently wondered why civil engineers haven't implemented either of the above techniques before. Chalked it up to "roads don't freeze enough".
Thoughts?
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Would having conducting concrete make it easier or harder to prevent electrochemical corrosion in reinforced concrete?
Intuition is telling me "yes to both", but I'm not a Civ...
Actually, the concrete, if it is like normal concrete, would probably explode instead of melting...the little air pockets inside it expand until they break the structure. It's neat. Hold a blowtorch to some concrete sometime---it crackles!
It sounds like the concrete still has a pretty high resistance, so I wouldn't count on a reasonable thickness forming a good Faraday cage. With the conductive stuff costing At 2 or 3 times as much, you could likely get a better cage for less by just hanging metal mesh inside the forms and pouring regular concrete. (The mesh is part of your reinforcement, too.)
And the suggested use of electrically heated payment leaves me wondering where they plan to get free electricity.
But there is one good application for this. Electronics manufacturers need to control static throughout their facilities. Fixed objects are grounded by hooking up wires, but people walk around, circuit boards and parts are carried around on carts, etc., and the only way to ground these while in motion is through the floor. So we paid plenty for conductive tile, and some sort of conductive underlay. If we could have put a conductive layer in the concrete slab itself, it would have saved a bunch (even at 3x the price of regular concrete), and it would be more reliable and lower maintenance.
Most places only put as much salt as is necessary (Edmonton for example puts 6-12% salt in sand for the roads) as it's expensive and doesn't work below a certain temp.
As for slugs - I don't know what they do for the environment, but they sure are tasty!
"History doesn't repeat itself, but it does rhyme." Mark Twain
SpinalTap could have really used this technology when Niles was wielding his wireless guitar...
"These go to eleven."
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I thought a big use for these were going to be for heated runways - so you don't have to worry about de-icing them anymore. (I just hope they don't heat them too much and then you have a bunch of lizards just hanging out on the runway warming themselves.)
Where the wind blows, the tumbleweed goes.
This conductive concrete has some interesting properties. The number one use that leaps to mind is EMI protection.
:) (I don't think anyone has proven that non-ionizing radiation causes cancer yet, so no worries...)
But for heating? Forget it! Two replies to this article mentioned something about how much energy it would require to melt ice. Now add the energy required to heat up the concrete. And know, that while electricity works quickly, it is just about the most expensive way to heat your home/whatever.
You might consider also, that while an abode of conductive material might be a great way to absorb stray radio signals coming your way, what are is your dwelling going to be emitting if you are hooking up AC voltage to it? If a micro-watt cell phone freaks you out, consider thousands of watts pumping through your house
Radiant heating systems are the way to imbed a heat source in concrete. The technology is gaining in popularity all the time, as it deserves.
Read more about it for yourself at: http://www.radiantcompany.com/ They are for profit, but the prices seem reasonable. They advocate do-it-yourself and lots of good info on the website.
It would be great to hear from an HVAC engineer on this, but I don't think they will tell you much different.
Bollux (a BSME)
If large structures are made with conductive concrete, it could create a broad spectrum RF nightmare in cities.
Today, large buildings reflect radio signals, creating interference for many signals in the shorter wavelength (6m to 30cm) bands. Imagine how much worse this would be if the buildings them selves had strong electromagnetic fields, or worse yet, emitted AC fields?
Also, these structures will convert radio signals and other EMF into electric current. Theoretically, it is possible that such current could be in the tens of milliamps or even higher, making for passive RF radiators.
I know we already use a lot of steel in buildings, but this is usually grounded and steel is a really poor conductor compared to something like copper or silver. I'm assuming this conductive concrete has much better electric conductivity than steel.
Vortran out
Knowledge is like ignorance.. too much can be just as bad as not enough.
Something I discovered with a neon transformer is that most things are conductive to some degree if you apply enough voltage :) concrete included.
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Or even the toilet seat. Low level current should be enough to keep it nice and toasty. Really would only need a few degrees above room temp to be MUCH more comfortable
There are heated toilet seats purchasable.
The problem, as with all great inventions, is the idiot factor. Joe Schmoe cracks the toilet seat or busts the wires with wear. One dark night he stumbles into the bathroom, whizzes on the seat, salty urine hits electric current, and it's "Don't Whizz on the Electric Fence" time. And then we get another lawyer-flinging spurious lawsuit or Darwin Awards candidate.
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The bridge-deicing idea isn't unreasonable. From their numbers, for $500 per storm, you could de-ice a bridge 200' long and 4 lanes wide. That compares favorably with sending out snowplows, salt trucks, and such.