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Transparent Concrete

Posted by michael on from the mandated-by-anti-terrorism-act-of-2004 dept.

rakerman writes: "The Economist reports in How to see through walls that development is underway on translucent concrete, with hopes of eventually developing transparent concrete. Can transparent aluminium be far behind?"

29 of 361 comments (clear)

  1. But what about the birds? by Eharley · · Score: 5, Funny

    Won't translucent structures lead to an increase rate of smack death amongst bird populations?

    1. Re:But what about the birds? by IainHere · · Score: 5, Funny

      I used to walk over a bridge with large glass windows, where there was a silhouette of a bird of prey. On the back was a caption that read "this cut-out is here to scare off small birds, which used to fly into the bridge and *subsequently* kill themselves". I often wondered why, having survived hitting the bridge, they would want to commit suicide. So perhaps they'll do the same on transparent concrete?

    2. Re:But what about the birds? by HarryTuttle · · Score: 4, Funny

      I often wondered why, having survived hitting the bridge, they would want to commit suicide.

      Embarrassment

      --

      Don't fight it son. Confess quickly! If you hold out too long you could jeopardise your credit rating.
  2. Hmm... by Drakin · · Score: 4, Informative

    Well, it's nice to see innovation within the construction sector isn't dead. Even for something that seems so off the wall as transparent (or currently, translucent) concreat can give birth to innovative new designs and possibilities from architechs.

    I mean, I can just see a wall done with a bubble effect (with slighly differnt opacities in the aggitates and clear binding coumpound).

    Only thing is, once transparent concreate is perfected... how are the mobsers going to get rid of bodies if they can't throw them in the foundation of a new building anymore...

  3. Re:I may as well say it.... by rehannan · · Score: 5, Interesting
    From the article:
    He has visions of cities that glow from within, and buildings whose windows need not be flat, rectangular panes, but can be arbitrary regions of transparency within flowing, curving walls.

    That sure sounds remarkably like Apple's philosophy...

  4. How to see through walls by Hal-9001 · · Score: 4, Funny

    They're called windows, and they're usually made of a neat transparent material called glass... ;-)

    Seriously, though, any slurry-based material like concrete is most likely to be opaque because microscopic structures tend to scatter light. You only need to pour a glass of milk to see this in action.

    --
    "It take 9 months to bear a child, no matter how many women you assign to the job."
    1. Re:How to see through walls by Pathetic+Coward · · Score: 5, Funny

      Windows is a trademark of Microsoft Corporation.

      Please use the term "transparent exterior access devices".

  5. Transparent aluminum by digitalunity · · Score: 4, Interesting

    I seriously doubt we will ever see transparent aluminum. In order for it to succceed, the atoms would have to be aligned in a crystaline matrix. Such a matrix would likely create a hard, yet weak substance.

    It would have much strength, yet it would fracture easily. Its called "Modulus of elasticity"; something certain steels(H11 namely) holds in spades. I doubt even if it could be produced, people would find it of much use.

    --
    You can't legislate goodness. Let each to his own destiny, by will of his freely made choices.
    1. Re:Transparent aluminum by Hal-9001 · · Score: 5, Insightful

      Such a material already exists--in fact it predates human civilization. It's called Al2O3, or alumina, and more commonly known as sapphire (or it's chromium-doped cousin, ruby). It has a hardness of 9 out of 10 on the Mohs scale (the only harder material I know of is diamond) and is transparent in the absence of impurities. However, it is not an alloy--it's a crystalline oxide.

      Metallic aluminum cannot be transparent except in thin films; this will be explained in a reply to the top-level post in this thread.

      --
      "It take 9 months to bear a child, no matter how many women you assign to the job."
    2. Re:Transparent aluminum by Hal-9001 · · Score: 5, Informative

      The reason you will never see transparent aluminum is not because of a lack of crystalline structure--in fact, I think metals generally are crystalline or at least have a crystalline microstructure. The reason that aluminum, and basically all metals, are opaque is the same reason that metals tend to be shiny. Because there are a lot of free electrons in metals (which is why they conduct electricity well), the electric field of light expends energy driving these free electrons (therefore metals are opaque), which in turn reradiate light back in the direction of the incident light (therefore metals are shiny). The amount of light that gets through goes as e^-ax where a is a constant and x is the thickness of the metal, so in a very thin metal film (e.g. mirrored sunglasses) you can still get some light through, but for any measurable thickness of metal (e.g. aluminum foil and anything thicker), the amount of transmitted light is negligible.

      I know this is a very hand-wavy explanation, but it's hard to explain without a pretty advanced background in electromagnetics. If you want an explanation of this from a rigorous electromagnetic point of view you can try wading through Chapter 14 of Principles of Optics by Max Born and Emil Wolf, but its mostly math with very little physical intuition or explanation.

      --
      "It take 9 months to bear a child, no matter how many women you assign to the job."
    3. Re:Transparent aluminum by cowbutt · · Score: 5, Funny
      I doubt even if it could be produced, people would find it of much use.

      I dunno. I find it invaluable for transporting live whales in my time-travelling starship, complete with enough water to for them to move around in.

      I could use steel or something, but, darn, I like to press my nose up to their enclosure during the journey.

      --

    4. Re:Transparent aluminum by markmoss · · Score: 5, Informative

      I'll try to re-state Hal-9001's post in a little different form:

      Electromagnetic waves consist of oscillating electric and magnetic fields in alignment so as to be self-perpetuating. The changing magnetic field creates an electric field a little further on, and the changing electric field creates a magnetic field still further on, etc.

      First consider a radar beam approaching a metal surface. The E-field will cause the free electrons in the metal to move. This transfers the energy of the beam into electron motion. And with several pages of math that I went through once and never want to again, it can be shown that the electrons move so as to create a mirror-image field, re-transmitting the beam at the angle of incidence -- in other words, a reflection.

      Due to resistance to electron movement, the reflected beam will be somewhat weaker, the missing energy being absorbed as heat. If the metal is extremely thin there might not be enough free electrons to fully absorb the incident beam, so part of it passes through. In an insulating material, electrons are tightly bound to molecules, and so cannot range far enough for strong interactions with the beam, and so most of the beam will pass through (the material is "transparent" to radar). However, electrons can shift around within the molecules, which causes refraction, partial reflections, and absorption.

      Things are different for x-rays, because the individual photons are pretty energetic and the wavelength (size of one photon) is close to the size of an atom. So it's more likely to be the inner electrons still bound to the atoms that wind up trying to capture the x-ray, and only rarely does this succeed -- most of the x-rays get through several inches of all but the densest materials.

      Visible light photons are in-between in size, large enough to interact well with the free electrons (reflection), but small enough to also be affected by bound electrons. (Selective absorption by the bound electrons gives copper and gold their color.)

      Most insulators are not transparent to visible light, except as very thin films. Most insulators (like metals) consist of irregular aggregations of tiny crystals. The interactions with the electrons bound in molecules will reflect some light, absorb some, and refract all the rest. In most insulators, the interaction varies with the polarization of the photon and the angle of the crystal; since each crystal is oriented differently, each interface between crystals refracts and reflects light in different directions, so the light that isn't reflected from the external surface is scattered and (mostly) bounces around inside the material until absorbed rather than passing through.

      Most transparent materials are glasses, with no crystal structure, and so no grain boundaries to scatter the light. Single crystals may also be transparent, although it's pretty hard to grow a single crystal as big as a windowpane. Multi-crystalline insulators can be translucent if sufficiently free of the atoms or molecules that absorb light, that is if the light is scattered but not absorbed eventually it will find it's way back out of the material. Concrete could be translucent if both the aggregate and the cement were free of light-absorbing materials, but I think the price would be extremely high.

      Possibly a multi-crystal insulator could be transparent if the refractive index did not depend on orientation of the crystal or polarization of the light, and if all the crystals fit together neatly and had the same refractive index. Or use glass beads for aggregate and somehow make the cement match the glass?

      Metals by definition have free electrons, which strongly reflect and absorb visible light. If it's transparent, it's not a metal.

      You can form Al2O3 into fairly large crystals, and maybe it could be a glass too. It's stronger and much harder than silica-based glass, so it would make a great windshield, if you didn't mind the cost of using diamonds for cutting and polishing.

  6. Transparent aluminium by mmontour · · Score: 5, Informative

    Can transparent aluminium be far behind?

    It's already here, although in the form of an oxide rather than the pure metal.

  7. Metropolis Magazine Article, April 2001 by bradlauster · · Score: 4, Insightful

    Apparently neither The Economist nor Slashdot knows the difference between translucent and transparent. Ugh.

    Anyway, this is old news. Metropolis magazine reported on the development of translucent concrete back in April 2001.

  8. A good weapon against terrorism... by heretic108 · · Score: 4, Funny

    would be to legislate that all new residential and commercial dwellings be built from transparent concrete.
    Anyone refusing to demolish their existing house would be added to a database of 'potential conspirators'.
    This would be quite consistent with recent 'anti-terrorist' surveillance legislation.
    Also, the boom in building would boost the flagging economy.
    Imagine whole neighbourhoods of people living in complete exposure, proving they're real honest patriotic Americans.

    --
    -- In the beginning was the WORD, and the WORD was UNSIGNED, and the main(){} was without form and void...
  9. Transparent != Translucent by Osty · · Score: 4, Informative

    There is a very big difference between "transparent" and "translucent". The former means that light passes through the material almost completely unchanged (a certain amount of distortion is okay, but the point is that you can make out what's behind it). Translucent means that light is transmitted, but it's diffuse and you can't make out what's behind the material. This concrete is translucent. It's not transparent (read the article).

  10. Transparent building materials by Hougaard · · Score: 5, Interesting

    The real problem with transparent building materials is that people inside want to control the transparency, just look at your own home, you got curtains and shades on all(most) windows.

    A classic problem with new hightech buildings (Glass 'n metal) is climate control, its nice to be able to look outside, but if the sun is starring you right back its not that fun. So you tint the windows :)

    The next problem is that in those buildings the light that gets through is not white light (sunlight) anymore, and working in that kind of buildings can cause depressions very similary to winter depressions.

    Remember: Architects are just building nerds :)

    1. Re:Transparent building materials by Hal-9001 · · Score: 4, Informative

      It's a shame that electrochromic windows haven't taken off. I first read about them in Popular Science, probably about 10-15 years ago, and if I recall correctly, they were used in a concept car by Ford (I could be mixing two Popular Science articles together), but they allow you to electrically darken and lighten windows, and they actually reflect light and heat (unlike liquid crystals, which just scatter light and heat but still let them through). I'm not sure, but they might also be wavelength-independent, i.e. reflecting all colors of light equally. The obvious barriers to their widespread adoption are probably cost and the ability to make panes large enough to use as windows.

      --
      "It take 9 months to bear a child, no matter how many women you assign to the job."
  11. Is it really concrete? by Eminence · · Score: 5, Interesting

    Can material described in the article really be called "concrete"?

    As it is written there its only resemblance to concrete is that it consists of coarse aggregate, fine aggregate and binding agent. But this is not a recipe for concrete only - also for other materials. Also, Dr. Price's secret material can't be poured or produced on site - one the main reasons of traditional concrete popularity. It would probably find its use in form of blocks of translucent material, that could be used to enhance possibilities for architects but what Dr. Price is trying to do is another building material, which is very interesting indeed but can hardly be called "concrete".

    1. Re:Is it really concrete? by Hal-9001 · · Score: 4, Interesting
      From the story:
      Technically, concrete is simply a mixture of three ingredients: big lumps of material called the coarse aggregate (such as gravel), smaller lumps called the fine aggregate (such as sand) and a binding agent, or cement, to glue it all together into a solid. So translucent concrete, in theory, should be fairly easy to make using bits of plastic or glass of various sizes, with some kind of transparent glue to act as a binding agent.
      This sounds more like a composite than concrete to me. The Dictionary of Composite Materials Technology defines a composite as
      A multiphase material formed from a combination of materials which differ in composition or form, remain bonded together, and retain their identities and properties. Composites maintain an interface between components and act in concert to provide improved specific or synergistic characteristics not obtainable by any of the original components acting alone. Composites include: (1) fibrous (composed of fibers, and usually in a matrix), (2) laminar (layers of materials), (3) particulate (composed of particles or flakes, usually in a matrix), and (4) hybrid (combinations of any of the above).
      By this definition, "transparent concrete" is a particulate composite of plastic or glass, probably in a matrix of epoxy or resin. Concrete is also a composite by this definition, but despite what my civil engineering friends might try to tell me, that doesn't mean that all composites are concrete. ;-)
      --
      "It take 9 months to bear a child, no matter how many women you assign to the job."
  12. Light Pollution by zephc · · Score: 4, Insightful

    Buildings glowing from within? This is terrible for astronomers... the added light pollution would further ruin the viewing conditions for many great observatories.

    --
    "I would say that 99 per cent of what my father has written about his own life is false." - L. Ron Hubbard Jr.
    1. Re:Light Pollution by foobar104 · · Score: 5, Funny

      Buildings glowing from within? This is terrible for astronomers... the added light pollution would further ruin the viewing conditions for many great observatories.

      Maybe that wouldn't be so bad. I say, the sooner we got astronomers off the surface and up to the far side of the moon, where they belong, the better.

  13. Glass Houses by Perdo · · Score: 5, Funny

    If you lived in a transparent concrete house would you still have to refrain from stone throwing?

    --

    If voting were effective, it would be illegal by now.

  14. Remember the "clear craze" several years ago? by Ukab+the+Great · · Score: 4, Funny

    First we had clear Pespi.
    Then we had clear deodorant.
    Saturday Night introduced us to clear gravvy.

    Like clear concrete was that far behind?

  15. I know how this one started... by Andy_R · · Score: 4, Funny

    Architect "...are the stairs, and this is where the wi..."
    Programmer "NO! NO! I will not have windows installed!"

    --
    A pizza of radius z and thickness a has a volume of pi z z a
  16. Edible Concrete by Anonymous Coward · · Score: 5, Funny
    Edible concrete has been with us for years:

    coarse aggregate - dried fruit
    fine aggregate - flour
    binding agent - eggs.

    It proved so popular, it's got its own name - cake!

    Let's face it, Marie Antoinette would've looked a bit of a dork saying "let them eat edible concrete."

  17. Lens and the Sun by Paul+Johnson · · Score: 4, Interesting
    I can see a whole new collection of risks here, especially if there are any curved surfaces involved. At various times of the day a transparent product would focus the sun's rays into various hotspots. Some of these might be intense enough to cause burns or even fire. The lenses would not be terribly efficient, but they would be very large.

    Paul.

    --
    You are lost in a twisty maze of little standards, all different.
  18. Re:The LCD variety has been done by A+nonymous+Coward · · Score: 4, Informative

    modern windows...have a higher R factor than a lot of walls

    Not bloody likely. Even triple pane windows aren't much more than R-3 or R-4, even if you add in Low-E and all that, you don't get much more. 6" walls (USA) easily get R-38 with insulation. Maybe if you had simple plank walls your windows would be higher.

    --
    Infuriate left and right
  19. Fire resistant? Or toxic smoke as it burns? by Derek+Pomery · · Score: 4, Insightful

    Don't see it mentioned anywhere in the comments yet, but after reading the article, the first thing that concerned me is that the nice thing about a concrete building is that it will hold together when it catches fire, not melt, puddle, and add to the blaze with choking poisonous smoke.

    Hopefully the designer is taking into account other properties besides strength.

    --
    -- perl -e'print pack"H*","6e656d6f406d38792e6f7267"' /. ate my old sig. Bastards.