Expert: Arshad Khan - 8/30/2005

Question
hmmm..it's possible I am incorrect about the direction in which the fiber optics are laid, and each layer might be laid orthoganally to the previous layer, but, regardless, cost is my limiting factor.  I'll experiment with what you described.  I heard there may be a police training academy in the works in Kuwait which utilizes tanslucent concrete in its construction.  I'd love to make a sound proof concrete bunker in which I could play my drums.  If I found a good trnaslucent concrete recipe, I'd make one, provided i could figure out how to sound proof the air vent, which i assume would be a necessary feature in a small concrete chamber with several musicians crammed inside.  I don't suppose you could inform me as to how to sound proof an air vent?  (This Q&A service is so interesting that I fear I may  make a pain of myself.  if you tire of my questions, just say so).
Thanks again, Arshad.

 I'd like to see humane treatment of prisoners take effect on a larger scale than reforms at Guantanamo alone would represent.  I think behaviorist science has effectively proven that punishment is inefficacious as a means of reforming people or any animal, for that matter.  So I am dismayed and disgusted to learn that army teams of behaviorist psychologists ("biscuits" they're called, this derived from their army designation acronym) have been fine-tuning the interrogation tortures inflicted upon certain Guantanamo prisoners in order to maximize their anxiety levels.  I think the "biscuits" will fail at their larger goal of obtaining useful information from the few prisoners who actually posess it, and are not merely former Afghan dirt farmers.  But any military will always tend towards such inhumane foolishness, and must be held in check.  I think it's no coincidence that science is being denigrated at Guantanamo right alongside the natural rights of the inmates.  (Some have been tortured, but more cry "torture!" for propagandistic reasons, I strongly suspect.)  This Bush administration ignores science whenever science reaches a politically inconvenient conclusiuon.  I think G.W. is a religious simpleton and a conceited, useless son of a rich man.  That he was ever even considered for the presidency disgusts me and greatly worries me about the health of my country.  Furthermore, what many people fail to realize is that the U.S. has miltary bases in Germany and Japan to this very day.  I am skeptical that we will pull out of Iraq any time soon.  I've written way to much to ever justify it on the basis of your one little comment about Guantanamo, which was somewhat asinine, by the way - so welcome!  I didn't even organize my thoughts, just blurted it all out, Gee whiz.  I'll just stop there.  Have a good day.  ..But Guantanamo is just a few people who have it bad but get a lot of attention.  Prison reform everywhere, sez me

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Followup To
Question -
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My understanding from a recent Science News is that the concrete is poured layer by layer into a formwork, and that on top of each layer of poured concrete, a layer of parallel fiber optic strands are laid, always in the same direction.  Apparently the fibre optic strands do not interfere subtantially with the concrete's strength.  I doubt that quartz and glass aggregate would perform as well as the fiber optic strands.  The Science News article said that one could shine a flashlight at one end of a 40 foot long beam, and at the other end a light would be visible from the flashlight.  YOu make a good point about rebar.  The 40 foot long concrete beam mentioned in the Science News article may transmit light over its length, but I suspect it would not have many practical structural uses unless it were pre- or post-tensioned, or otherwise steel-reinforced,  and that the presence of such reinforcement would detract from the light transmitting effect.  If any of this sounds blatantly incorrect, please let me know.  I wish I knew the date of that Science News issue, but I can tell you that concrete was the focus of the issue.  Is it hard for an average joe to find fiber optic cables for sale?  Are they expensive?  Thanks for your time.


Followup To
Question -
I am really excited by the recent invention of translucent concrete.  Can you tell me if anything has been made which employs it towards  improving some design's overall utility and functioning? Or is it primarily an aesthetic advancement?  How can I make my own in my garage?  I've mixed concrete before from sand, cement and gravel and I'd love to experiment with my own designs in this material.  Thank You for providing this wonderful service!  As if civil engineers didn't do so much for humanity already...
Answer -
Hi John,

As you said, this is a fairly recent invention and not much has been published about it. All I know is that it is made by mixing glass fibers into the combination of crushed stone, cement and water. I would imagine that if the stone is say quartz , which is also translucent,(or even broken glass, such as a shattered windscreen of a car) then the effect would be even greater.

So far it has been used only for paving slabs and blocks, i.e. in precast units. I can imagine that having rebar in a cast-in-situ construction may spoil the effect.

You can no doubt experiment with different materials, but the best translucency will be achieved probably by careful grading of quartz/glass aggregate.

Hope that helps!

Kind regards,

Arshad
Answer -
Hi John,

What you describe would probably only be translucent along the longitudinal axis, but using quartzglass aggregate and/or glass fibres it would be so in all directions.

I can imagine fibre optics being quiet expensive- check it out from computer/telecoms companies.

I forgot to answer your question about usage. I would think blockwork made from this would be very useful for enclosures to bathrooms, stairways, lifts, and such-like where you need light but not necessarily privacy. Could also use for external walls of say living rooms and thereby the living room would "glow" when viewed from the outside, and tree trunks, etc would be visible from the inside.

Could also be more humane to use in Guantanama Bay instead of the cages!

Hope that helps!

Kind regards,

Arshad

Answer
Hi John,

I am not an expert in sound proofing, but I guess something like a car silencer would work- lots of staggered baffles with glass fibre padding?

Hope that helps!!

(b.t.w. I concur with your political views, but you will agree this is not the forum for it.. ;-))

Kind regards,

Arshad