Welcome to European Tribune. It's gone a bit quiet around here these days, but it's still going.

About concrete and its avatars...

by margouillat Fri Nov 25th, 2005 at 03:56:48 AM EST

From the front page ~ whataboutbob

Most people associate modern style architecture "à la Corbs" with concrete. And you often hear "It's just a concrete building, you know..." in a pejorative way, conveying the feeling that it's some grey old thing, with some rusting rods and a lot of dust...!

So most  buildings today are designed with some fashionable steel, stone, wood, glass claddings. On cheaper housing projects, it's about plastic grout in funny colors, barely hiding some concrete blocks.
Visible concrete is seldom seen, and when it does exist, nobody recognize it as such !

However, concrete is not only an excellent building material, but, on these days of sustainability, it might be one of the most high-tech material...


Concrete and cement.
The "old" concrete is the one most people know. It's a dosed mix of cement powder, fine sand and more coarser sand or pebbles (three gradings).

It was re-discovered by Louis Vicat in 1817 by sheer accident while he was dumping a missed batch of lime in the Rhone river, as usual, as lime will dissolve in water, when bargemen came ranting that he threw rocks in the river as this time they wouldn't melt...
He then rediscovered what was the "famed" Roman mortar lost knowledge in the dark ages ...!

The Pantheon's dome in Rome is made of this roman concrete, (2 century AD)

This "brand new material", cement, was first used to make a small ship hull before being used for bridges and lighthouses, then at last, for more "common" buildings (Perret, Nervi, le Corbusier among many others).

Of course for structural use it had to be reinforced with steel bars so as to withhold tension forces and not only the usual compression ones.

New formula.
In 1991 Pierre-Gilles de Gennes, physicist, has the Nobel prize of physics :

"for discovering that methods developed for studying order phenomena in simple systems can be generalized to more complex forms of matter, in particular to liquid crystals and polymers"

Yves Mallier (french engineer of the Ecole Française des bétons) was looking at the TV interview of de Gennes explaining for the layman the theoretical gradings ( marbles sizes to fit best in a given space). There were not 2, 3 nor 5 grades but 4!
So that week, Mallier tested a new grading in concrete... He added a super fine grade (finer then cement) that was an industrial waste, silica ashes (fumée de silice) and tested it...! The "new" concrete was born.

Because the "holes" in the usual concrete were "filled" by the new very fine grade, the concrete was watertight (fully) and had a higher resistance to compression. Usual building concrete: 15 to 30 MPa (MegaPascal)
"New" concrete: 100 to 200 MPa with laboratory products tested to 400 MPa.

The fiber path.
On another set of thoughts and since those old adobe walls of neolithic times, some searchers (quite a lot) wondered about reinforcement of concretes.
Concrete in structural use, has to have steel rods or bars for tension forces.  Without those bars, the test specimen would break sooner.
But what really happened at micro-metric scales ? Thousand of small hairline cracks appeared in the concrete, and joined to make bigger cracks that ended with the breaking of the whole test specimen.(to make it short!)

The big iron bars at, say, a beam scale didn't really stop the fine cracks but, like a giant staple held all that concrete matter together (ie. the beam "held" for a given strenght). After a tension limit it was those steel bars that played the tensile role.
Now what would happen if some mini staples were used to delay the joining of those micro cracks in the concrete matter ?
Surprise... It worked much better then the "life scale" steel bars ! It works so well that concrete made this way was a "ductile" (or tensile) material... Almost as good as a classical I beam of steel !

Fiber concrete and nanotechnology.
On one hand there was a new composition of concrete, on the other hand there was another technique to have the concrete in a ductile state... The "new" concrete was truly born !

Those "mini staples" or fibers are either organic (DuPont) or steel ones. The highest resistance is of course with the latter (till we find a cheap way of having nano-tubes of carbon or bacterium produced spider web). Sizes, sections, quantities are patented.

As most "true" building material in history that are the use of the "wastes" of the era's technology, these new concretes are "new" today because of industrial wastes recycling... The silicium ashes are from the computer processor and zirconium industry... And the small, thin, steel fibers are from the shredding of radial tires !

To give a more practical perception of this material, most concrete slab for a 6 meter span is about 20 cm thick (usual slab for housing)... While with these BFUP (Béton de Fibre Ultra Performant) you could narrow it to a thickness of less then one centimeter ! (of course it doesn't allow for acoustic and thermal inertia, those must be designed independently). If it wasn't for the sag, it could be 0.5 cm. and if it was a cupola or a shell design, there would be no sag and could stay below half a cm...

Some advantages...

It is a tensile material... So it works well in seismic building conditions. Think of Kashmir (frame structure and earth filling), Bam (Iran) Alger (Algeria) etc...

It's dense, but you need less matter... So buildings are lighter and cost less and can optimize bad lands for foundations.

It allows for fire regulations... Much better then steel, as it keeps it's mechanical properties much longer. Compete studies have yet to be done. The only example we have is the fire in the Channel tunnel with very high temperature (oven style). This fiber concrete acted like wood, like if it was laminated with micro plies that delaminated one after the other in time.

It's watertight... So you don't need all those tar derived products (that always leak one day anyway!)

It's "easy" to make... Well, you do need an oven for cement, but it doesn't have to be carbon oriented as in a steel mill. It could even be a solar one! Most materials for cement can be readily found in any country, and the ultra fine grade can be anything finer then talc. After a Tsunami, it would be easier to build some cement plants and leave the locals to build their own architecture... (Thus providing new jobs)!

It's molded... As all concretes, and can be readily prefabricated. New additives (in old as new concretes) can give it a very "liquid" phase, allowing for "pumping" the concrete in the mold, even from quite far away (100 m) reducing drastically the noise of most works (for a better acoustical comfort in cities for neighbors as for workers).

It allows for nano technology... Such as nano LEDs, nanotubes for "breathing" through a concrete slab (as thynsulate or such), and catalyst inclusions that with UV breaks organic molecules that are the pollution "glue" (Pope's chapel in Vatican, and a Police center in Toulouse).

It allows for color and finishings... I saw a black polished sample that looked and felt exactly like those black shiny ashtrays you find in cafés ! The surface aspect can take very swallow motives (tenth of mm) and keep them durably.

And of course architectural styles, shapes and form would change... "Form follows matter!"(could be Aristotle) :-)

Of course it costs more the the "old" concrete and less then steel, but, between the rising prices of steel and the reduced volume quantities needed, in practical use it shouldn't shift much building prices.

As sated, it's mostly a French design... But the few existing built example (mostly bridges) are not in France, but in Canada and in Seoul (sigh)... As usual, we'll have to wait another 20 years before it's used commonly... Unless we get to the 100$ the barrel point :-)

Some "home made" tiles specimen...
Image hosted by PicsPlace.to

For the braves...

A simple powerpoint in pdf

Miss Habel thesis in english (pdf)

M. Parant thesis in french (pdf)

A link to Calcia's auto cleaning concrete

Display:
OK guys, it's my very first diary... :-)

"What can I do, What can I write, Against the fall of Night". A.E. Housman
by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Tue Nov 22nd, 2005 at 01:00:21 PM EST
This seems a very promising new-old technology.  An excellent and informative diary.  I wonder what you can do when you have some practice.  :}

We all bleed the same color.
by budr on Tue Nov 22nd, 2005 at 04:08:57 PM EST
[ Parent ]
A first diary -- on the European Tribune -- about concrete? I like it.

These new concrete materials, about 10x stronger than their conventional relatives, are a reminder that rearranging matter on a fine scale can change properties enormously. There are factors of 10x or more to be gained in many properties of materials and systems when we get better at structuring matter using low-cost methods. Biology gives a hint that the structure can of matter be controlled all the way down to the atomic level, and inexpensively at that. The consequences of this for energy and resource policies and politics have scarcely been considered.

Words and ideas I offer here may be used freely and without attribution.

by technopolitical on Tue Nov 22nd, 2005 at 04:32:11 PM EST
[ Parent ]
Exactly !
Scale is important, and while we work with chemistry (molecular level), physics is either looked at the sub atomic level or at the engineering standard level (like Newton's apple :-) ).
What was called in 1936 the Chimie-Physique (Curie), working at what is called today the nano scale (bricks of several big molecules) is a future bearing technology... Not so because it's high-tech (or even low-tech in some cases), but because for the same amount of energy you get a much higher effectiveness.

But then, why on European Tribune ? Maybe because, unlike the casual french politician, the knowledge of how building can progress can be a real asset in coining a new way of living (ergo: a new society).

 These materials are important in public health first !

  • We use asbestos for fire proofing, we scare because it can give cancer (not knowing that there are 2 asbestos minerals, the other not being related to cancer).
  • We create an array of electro magnetic fields (related to frequent off work days) with machines and transformers.
  • We are keen on windfarms, solar panels, solar heating, forgetting that some have it's own lot of health related problems (solar heating water temperature, ideal for Legionnela!)
  • We rant on energy (petrol or nuclear), mixing up the industry demand and the individual one. While with aerogel insulation (again silicia) we could light a few candles for a full day of comfortable temperature.
  • We care about immigration, but we don't even have a thought for the main employment - building works - that still kills or maim for life most of them, because we just love that "nice little house", so cheap !
  • We care about other people, other countries, mostly third world's ones, and we sell them our old rotten techniques, either creating a technical dependancy, or just polluting where we still can (Bopal).

It could go on for a while...!

The fight for a better world starts -also- at a lower level. Or how you deal and manage a territory (weather, crops, industry, cities), and how those techniques can be improved, creating new jobs, new relationships between people... Often in a subtle but very common way of dealing with it !

While I'm not an economist, neither a scientist, I was thinking of posting, from time to time, some diaries about those problems. Basic information at first, then the  "what we could do" with those techniques and at what relative cost... Neither utopia nor dystopia !




"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Wed Nov 23rd, 2005 at 03:57:30 AM EST
[ Parent ]
Excellent comment - worth a diary of its own, mon cher margouillat!

(Expect this concrete diary to be promoted to front page later today)

In the long run, we're all dead. John Maynard Keynes

by Jerome a Paris (etg@eurotrib.com) on Wed Nov 23rd, 2005 at 04:38:07 AM EST
[ Parent ]
What joy, what joy.

Innovation at the scientic level, various implementation via "tiger teams" and, ultimately, politics and economics.

I'm one happy scientist reading your post. You've all the three tiers I generally rave about practically covered within one post.

Not to mention you mention silica insulation. Wowsers. Why didn't you start a diary any sooner?

by Nomad (Bjinse) on Wed Nov 23rd, 2005 at 09:43:56 AM EST
[ Parent ]
Alas... Practice is one thing, but having a fluent, easy, humorous, writing style in English is just another !!!! (It's so easy in french!)

"What can I do, What can I write, Against the fall of Night". A.E. Housman
by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Wed Nov 23rd, 2005 at 04:07:32 AM EST
[ Parent ]
It's the same challenge for all of us who are not of English mother tongue. So, this makes this diary a even greater work.

Interesting topic. I agree with you it is not the material, it is the architects. I have been in favor of a law that would force the architects to live or work at least for one year in each building they build. My guess is they would improve pretty fast.

by Fran on Wed Nov 23rd, 2005 at 04:19:01 AM EST
[ Parent ]
LOL :-)

Some did it ! But hey are now of a past generation (circa 80 years old)!

"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Wed Nov 23rd, 2005 at 04:46:07 AM EST
[ Parent ]
It's the same challenge for all of us who are not of English mother tongue. So, this makes this diary a even greater work.

And it's even a challenge for some who ARE of English mother tongue. :)

by gradinski chai on Wed Nov 23rd, 2005 at 08:35:01 AM EST
[ Parent ]
Why do we restrict ourselves to writing in English? Has this issue been discussed?

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman
by Carrie (migeru at eurotrib dot com) on Wed Nov 23rd, 2005 at 08:43:01 AM EST
[ Parent ]
Perhaps out of an abundance of generosity to we ignorant Americans who know little else?   Well I for one appreciate your consideration.


We all bleed the same color.
by budr on Wed Nov 23rd, 2005 at 10:08:13 AM EST
[ Parent ]
I often find myself pointing out some resource to a fellow Spaniard only to be dismissed with the argument "uf, that's in English!".

From the Eurobarometer on Europeans and Languages, English is the most common foreign language at 34%, followed by German at 12% and French at 11%, and finally Spanish and Russian at 5%. On page 10 there is a table of "languages most commonly used". They are, in order:

  • English 47%
  • German 30%
  • French 23%
  • Italian 15%
  • Spanish 14%


A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman
by Carrie (migeru at eurotrib dot com) on Wed Nov 23rd, 2005 at 10:22:02 AM EST
[ Parent ]
Long ago in another life I studied Spanish at a small liberal arts college.  I was fascinated by the evolution of the Romance languages as the Roman empire dissolved and regional dialects of Latin acquired the unique characteristics of their own time and place and people.

For good or ill the imperial language of this age is English.  As the sun, having already sat on the British empire, declines in the west of the American, I can't help but wonder what family of English-based (or, more accurately, Germanic-based) languages scholars will study a millenium or two from now.  And I can't help but wonder what the lingua franca of that age will be.  I would not be at all surprised if it were some dialect of Chinese.

We all bleed the same color.

by budr on Wed Nov 23rd, 2005 at 11:48:29 AM EST
[ Parent ]
Yeah, Chinese is second on my list of languages to learn next (Czech is first, on account of my girlfriend).

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman
by Carrie (migeru at eurotrib dot com) on Wed Nov 23rd, 2005 at 11:52:34 AM EST
[ Parent ]
Fairly extensively discussed, actually. Anyone can write in their own tongue, though the problem will be limited understanding by the readers who don't read that language...and then there's the danger of a writing becoming National/regional. Plus, as others have noted, there's us ignorant English-only readers (have mercy on us). English has been sorta accepted as the common tongue...though, again, that shouldn't stop someone...it would just take someone interpreting. (And I tried the interpreter, but the device is very literal, so the subtle meanings are lost...)

"Once in awhile we get shown the light, in the strangest of places, if we look at it right" - Hunter/Garcia
by whataboutbob on Wed Nov 23rd, 2005 at 10:33:47 AM EST
[ Parent ]
I was wondering whether something similar to Booman's could be set up where there would be recommended diary lists in different languages instead of different regions.

It might only make sense for German and French given the number of first- and second-language speakers (see my Eurobarometer summary elsewhere on this thread).

Then again, ET is too small to fragment in that way. On the other hand, does deference to the < 13% English monolinguals justify leaving out the 53% of EU residents who don't feel they can hold a conversation in English?

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman

by Carrie (migeru at eurotrib dot com) on Wed Nov 23rd, 2005 at 10:44:25 AM EST
[ Parent ]
Plus, my German (and French) are shadows of their former self... it would be fun and instructive to blog in them. And you yourself, living in a German-Speaking canton and working in a French-Speaking one, could benefit from trilingual blogging!

A society committed to the notion that government is always bad will have bad government. And it doesn't have to be that way. — Paul Krugman
by Carrie (migeru at eurotrib dot com) on Wed Nov 23rd, 2005 at 10:53:28 AM EST
[ Parent ]
I have been in favor of a law that would force the architects to live or work at least for one year in each building they build.

Some years ago I worked as an electrician.  A common grumble among those I worked with was that architects should be required to build their first design with their own hands.

We all bleed the same color.

by budr on Wed Nov 23rd, 2005 at 09:54:28 AM EST
[ Parent ]
I used to be a landscape gardener, and I used to wish the landscape architects would have to trim the bushes they planted on those hillsides....

"Once in awhile we get shown the light, in the strangest of places, if we look at it right" - Hunter/Garcia
by whataboutbob on Wed Nov 23rd, 2005 at 10:35:00 AM EST
[ Parent ]
Have no fear on that score, mon ami.  Your English is much better than mine.

We all bleed the same color.
by budr on Wed Nov 23rd, 2005 at 09:51:54 AM EST
[ Parent ]
Great diary!  I grew up in Los Angeles where everything is constantly being torn down and replaced with parking lots and strip-malls, so I do have that lingering aversion to concrete.  Also, to grey, square buildings.  I never did understand why people built them.  

But then I read Wolfe's book, called (iirc) From Bauhaus to Our House, and it gave me a little bit of an understanding about the thinking behind it.  I feel sort of the same now with your diary -- I won't look at concrete quite the same.  Especially now that I know it was Rome's lost mortar!

Maybe we can eventually make language a complete impediment to understanding. -Hobbes

by Izzy (izzy at eurotrib dot com) on Tue Nov 22nd, 2005 at 04:26:11 PM EST
Eh, eh... :-)
Still, it doesn't mean that all what's done in concrete is great... Alas !
But it could be, because it's not the material's fault !

"What can I do, What can I write, Against the fall of Night". A.E. Housman
by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Wed Nov 23rd, 2005 at 04:01:01 AM EST
[ Parent ]
Excellent diary! Fantastic! Thank you for posting this. A bit of historical background too, to boot. Hope you post some more diaries on this topic, with some photos of interesting concrete architecture, from time to time. I like it...concrete is sustainable technology! That does add a new perspective (I think it has gotten a bad rap, because too many people use concrete in boring ways...)

Great first diary too!!!

"Once in awhile we get shown the light, in the strangest of places, if we look at it right" - Hunter/Garcia

by whataboutbob on Wed Nov 23rd, 2005 at 03:26:35 AM EST
Gee whiz... Thanks' That's a real compliment, coming from you !
Such feedback pushes me to think about a serial, from material to cities, skipping a bit the pure architectural part as I can't be really honest on that one :-)

"What can I do, What can I write, Against the fall of Night". A.E. Housman
by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Wed Nov 23rd, 2005 at 04:05:36 AM EST
[ Parent ]
That recipe that you gave out over the weekend...the gateau that I thought had three eggs in it...that was just a gateau recipe right?

If I use your recipe, will I be baking a cake or will I be making a brick? <snark>

Or does it depend on how well I bake? :)

Thanks very much for the diary. In my next life I'll be an architect; in this life I just settle for reading and watching documentaries. So thanks again.

by gradinski chai on Wed Nov 23rd, 2005 at 08:29:39 AM EST
Why wait for the next life ? Some of my students are 60 years old ! And my mother is still in university learning chinese (she's 90 years old)... :-)
There is no limit to pleasure...!!!!!!

"What can I do, What can I write, Against the fall of Night". A.E. Housman
by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Fri Nov 25th, 2005 at 05:54:00 PM EST
[ Parent ]
Thanks for a very interesting diary! Imagine the new architectural possibilities! I know one of the problems with reinforced concrete & fire was that toxins in burning carpeting or other material eroded some of the steel reinforcements even after structure seemed to have survived the fire just fine. I wonder how this new concrete would fair.

I've seen several concrete countertops and floors made of colored and/or polished concrete they look quite beautiful and nothing like the old gray concrete.

A little while ago I read about another interesting use of concrete in building emergency shelter & was able to dig up the reference. It's the "building in a bag" idea:


A pair of engineers in London have come up with a "building in a bag" -- a sack of cement-impregnated fabric. To erect the structure, all you have to do is add water to the bag and inflate it with air. Twelve hours later the Nissen-shaped shelter is dried out and ready for use.

The structure is intended to improve upon two current methods of providing emergency shelter: tents, which provide only poor protection, or prefabricated, portable buildings that are expensive and difficult to transport. Dubbed the Concrete Canvas, the shelter incorporates the best aspects of both forms. It is almost as easy to transport as a tent, but is as durable and secure as a portable building.

The inventors are engineers pursuing a master's degree in industrial design engineering at the Royal College of Art in London. William Crawford and Peter Brewin came up with the idea when they were thinking of an entry for the annual British Cement Association competition for new and innovative uses of concrete.

To see a picture click here.

by Alexandra in WMass (alexandra_wmass[a|t]yahoo[d|o|t]fr) on Wed Nov 23rd, 2005 at 10:38:14 AM EST
Thank you... I'm blushing !

The "shelter" problem is one I give my students each year ! In 2006 we might be working with ASF (Architectes Sans Frontières) on the topic!

There's no easy answers, as we all know that the blue ONU tents are still there 10 years after... So with a more permanent structure it would be the start of a "favella".

The point is to think in two phases, urgency and recovery of a local built tissue. The two are often very contradictory in space, volumes and wastes !
Because some good work have been done in favellas studies, the tendency today would be to design an urgency module (6 to 10 people) that could be used as the core of a future housing (simple or multi storied) that could be built by locals, with local materials and industry (we could help there too).
Drainages and future streets or accesses could be designed as 2 over-crossing weaves with common points.

The main point is that after the initial response (mostly military as they have the means to do it), there is a 10 years development program getting locals to work after the first year ( mourning, healing, family recomposing, etc...), with economical initiatives ( agricultural, fishing, small developments, etc...)!

Water plants and final draining being done in the first two years!

Well, that's the main scheme :-)
And it allows for a good level of complexity in architecture and in prefabricated techniques (core structure in fiber concrete, fillings in compressed earth, etc..!), while keeping the local knowledge and style and getting back people to work quickly (assisted syndrome) !


"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Wed Nov 23rd, 2005 at 11:17:12 AM EST
[ Parent ]
Now I just re-read through this slowly. Still great...and exciting. Makes me want to build a house! (I can see me on the corner now "Hey buddy, got a franc for my cement house?")

I'm emailing a link to a contractor buddy of mine.

Man...the stuff i learn around here...

"Once in awhile we get shown the light, in the strangest of places, if we look at it right" - Hunter/Garcia

by whataboutbob on Wed Nov 23rd, 2005 at 01:11:31 PM EST
By the way... I'm the guy who says that "individual housing should be a crime against humanity"...!

Of course I'm not making many friend when I state that... But at length, people who care about sustainability, eventually agree... :-)

(OK, now I'm ducking, as bricks might be flying low) :-)

"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Fri Nov 25th, 2005 at 05:57:23 PM EST
[ Parent ]
Next week... Insulation and Gel-Sol... :-)

Of course the Savoyards having a big advantage on Swiss, they only speak italian, patois, and occasionally french !
And of course they always used sustainable heating, sleeping just over the cows and with the poultry under the bed... Now what is a little smell between friends :-)

Le serveur Savoie

Arvi'


"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Wed Nov 23rd, 2005 at 05:04:36 PM EST
Very informative. A while ago, we mentioned on our blog the benefit of concrete in the rebuilding of houses in the aftermath of Katrina. This is a good follow-up. I hope you don't mind, I quoted your list of advantages on our blog (with a link to your blog and your posting of course. No cheating. ;-)
     Joker to the Thief
Blog at http://jokertothethief.blogspot.com/

The Joker, at http://jokertothethief.blogspot.com/
by The Joker (jokertothief@gmail.com) on Thu Nov 24th, 2005 at 12:59:00 AM EST
Interesting looking blog! (And I just saw Dylan in Zurich, and yep, he closed the show with "All along the Watchtower..."). Welcome to ET!

"Once in awhile we get shown the light, in the strangest of places, if we look at it right" - Hunter/Garcia
by whataboutbob on Thu Nov 24th, 2005 at 03:50:05 PM EST
[ Parent ]
No problems (sorry I couldn't answer sooner)! In fact I don't really care, as I feel knowledge should be a free flowing entity!
I'm of the very few architects who don't care about being known, recognized, publicized,etc... My belief is that we work for the sake of people...!

(I did work in "old" russia with some soviets (and the good old babushkas))! So maybe I'm an old stalinist at heart :-) :-) :-)

In a funny way, stating that you are a " stal' " is not so bad in France, because there are no real confusion with the "real thing"!

"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Fri Nov 25th, 2005 at 06:05:35 PM EST
[ Parent ]
In your projects do you use timber or steel beams laterally in the courses or pour to help protect the building from shear stress during earthquakes?

She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre
by ATinNM on Thu Nov 24th, 2005 at 11:57:46 PM EST
A quick reply (because of work!)... And I might not have understood the question ?!
Either you design a new building with anti-sysmic care, mostly architectural answers (volumes, weight, facades, etc.).
Or you intervene on existing buildings, having been stressed by a recent earthquake, but still usable (hair-cracks, but no real displacement of structure). In this case, instead of using timber or steel beams, a structure reinforcement with these new concrete can be designed.
Instead of beams, it would more be a complete "frame cube" (4 porticos) that could be set in each volumes (rooms). It could have the size and looks of some thick baseboards (ceiling and floors), thus allowing the use of those living spaces...
More then 30 000 flats are still stressed in Algier and that's as much families that are in danger, as the few new buildings that are built are for the thousands families that have no homes since the last earthquake.

Those concrete frames can be prefabricated and used just as steel is, either by clipsing (the concrete can be as thin as 2 mm) or by using the "nut and bolts" system (those being also in concrete)...

I'll get a more precise answer on saturday :-)

"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Fri Nov 25th, 2005 at 01:58:50 AM EST
[ Parent ]
You understood perfectly!

2mm frames?  As thin as that!?  How surprising!  I look forward to your "more precise answer."  

And now, I too, must get to work.


She believed in nothing; only her skepticism kept her from being an atheist. -- Jean-Paul Sartre

by ATinNM on Fri Nov 25th, 2005 at 12:10:31 PM EST
[ Parent ]
Without  really being more precise, there's another way to use these concretes... By projection!
In fact these new "high-tech" concretes work best in thin layers. A projected layer of about 5mm and 1 cm in the angles of a room would give you a fairly decent ductile shell. You could then clad it with plaster (or whatever) as it would be a bit "hairy"...
Of course it works best for small rooms of 5m to 6m span. And it depends of how the original building was built !

This projection technique is used for example on existing posts when you want to add some levels to an existing building and that the foundations are good enough.
You spray this concrete as an outward layer of the existing post, boosting it to the desired section, while people are still working in the office, the works being behind plastic sheets...

In conclusion, there are numerous ways to achieve the re-furbishing of stressed buildings. The "meccano" one being the less obnoxious in use and time and quantities... So surely the cheapest!

Two millimeters is quite easily obtained in a prefabrication controlled process (pressure molds).
Some, today, are thinking of designing window frames with this concrete. They would be as thin as the steel one's but with no corrosion and with a thermal resistivity nearer to wood. And we could leave aluminum to planes and boats...!

"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Sat Nov 26th, 2005 at 05:31:23 AM EST
[ Parent ]
What a great diary I somehow missed!

I have one question: is there any research in the concrete business to reduce even the CO2 emission from the chemical process?

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Fri Nov 25th, 2005 at 02:40:03 PM EST
The CO2 emission is linked to the chemical process of cement, usually 0,9 ton of CO2 for 1 ton of cement. This is mostly because of the furnace (kiln at 1800°) and the CaCO3 (calcium carbonate)...

The world production of cement (concrete mostly) is about 1 cubic meter per person and it is increasing!

To reduce CO2 emissions, several paths:
Linked to the process:

  • Electrical furnaces in nuclearized countries...
  • Solar furnaces...
Linked to the use:
* Less cement in concrete... That's the "new concretes", using more fly ashes and additives (chemicals). The ratio of cement in the final product is optimised and reduced, as the use of water (less quantities).

Some future paths:
Calcia's research on catalytic additives has lead to the "millenium concrete" (trade mark) that keeps the concrete free of the usual organic pollution... But there are experiments with other catalytic products with UV (sun) to break down other molecules.
Some of those are tested to de-pollutate sites by acting like a micro-filter with catalytic reactions (still in experimentation and so quite secret!).

Up to now, carbonation was a problem for concretes (pH), but with organic fibers it's not the case... So a special concrete (not very structural but could be used for fillings or cladding) could be used on buildings to either break CO2 in C and O2 (quite a lot of energy there) or to trap the CO2 in some other molecule like calcite or some other CO2 "trap"...!

It's just the beginning of the "customized material" industry :-)

"What can I do, What can I write, Against the fall of Night". A.E. Housman

by margouillat (hemidactylus(dot)frenatus(at)wanadoo(dot)fr) on Sat Nov 26th, 2005 at 04:59:21 AM EST
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