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Researchers Make Bendable Concrete 399

Posted by CowboyNeal
from the flexible-roadways dept.
karvind writes "PhysOrg is reporting that scientists from University of Michigan have developed a new type of fiber-reinforced bendable concrete. The new concrete looks like regular concrete, but is 500 times more resistant to cracking and 40 percent lighter in weight. Tiny fibers that comprise about 2 percent of the mixture's volume partly account for its performance. Also, the materials in the concrete itself are designed for maximum flexibility. Because of its long life, the Engineered Cement Composites (ECC) are expected to cost less in the long run, as well." Michigan roads must make the perfect test cases for this stuff, and I look forward to their improvement.
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Researchers Make Bendable Concrete

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  • A keyboard? (Score:4, Funny)

    by James_G (71902) <james@globalmeg[ ]rp.org ['aco' in gap]> on Friday May 06, 2005 @03:06AM (#12449149)
    How quaint!
  • Buildings (Score:5, Insightful)

    by antivoid (751399) on Friday May 06, 2005 @03:06AM (#12449151) Homepage
    Now finally we can see buildings that bend and shift better under harsh weather conditions such as wind and rain.

    The benefits of this extend greatly beyond that as well however.

    It will be intresting to see where this goes...
    • concrete submarine (Score:5, Interesting)

      by nounderscores (246517) on Friday May 06, 2005 @03:09AM (#12449163)
      I wonder if this new concrete may enhance the concrete submarine [popularmechanics.com] programme for deep submersibles.

      Being in something with a bit more toughness, and better tensile strenght might be more reassuring. A little less like going to sea in an eggshell.
      • by Anonymous Coward on Friday May 06, 2005 @10:00AM (#12450616)
        You're misinterpreting the Popular Mechanics article. These are not deep submersibles. The advantage of a concrete submarine, like the advantage of a WWII Liberty ship, is that it is cheap. That's it. Cheap. It doesn't perform better, it doesn't last longer, and if you're a civil engineer, you'd probably laugh at the idea of crawling into one and diving into the deeper depths of the ocean.

        The WWII Liberty ship had a design life of 5 years and a "positive" ROI if it managed to survive its first (outbound) trip to deliver cargo to Europe. The entire vessel could be completed in an average of roughly 60 days. You could build them quickly using forms, you could build a lot of them using cheap materials, and they couldn't be sunk quickly enough to cut off the British from the American industrial complex. Now imagine the concrete submarine. Same principle, different wartime purpose.

        Now the nerdly part. From a materials perspective, you're dead wrong.

        To start with, the nit: Concrete has practically no tensile strength in comparison to steel - reinforced concrete design assumes that all tensile strength is provided by the embedded steel rebar.

        Next, the myth: Concrete has good compressive strength - high strength varieties can have crush pressures exceeding 140 megapascals. Steel has much better compressive strength - high strength varieties can have crush pressures exceeding 2500 megapascals. Steel is stronger, but vastly more expensive. Concrete is weaker, but, literally, dirt cheap. Reinforced concrete is a practical compromise that optimizes economy versus loads for a particular design envelope (notice that modern skyscrapers do not have loads of reinforced concrete incorporated into their design).

        Next, the mechanical nit: unless you've designed a perfect sphere, your concrete submarine will not only have to resist compression. Various parts of the structure will experience "tension" in response to bending moments and shear forces that resist the spreading tendency that will occur in a non-spherical, hollow form subjected to a pressure differential (tension is in quotes because I'm referring to subelements that are being pulled apart, not to the entire cross section as is normally the case). You can mitigate this problem by using pre-stressed concrete, so that the entire structure is under compression, but you will have spent a portion of your compression resistance to eliminate that problem. Steel makes your life much, much easier.

        Finally, the materials problem: Concrete is porous and breaks down in marine environments as the salts attack the calcium hydroxide matrix, dissolving the cohesive minerals, depositing non-cohesive minerals, and splitting the crystalline structure like ice and the Old Man of the Mountain. Concrete is used in marine environments, but it deteriorates comparatively quickly. Now cycle your concrete though tens or hundreds of atmospheres of pressure in a marine environment. Your concrete will deteriorate even more quickly. Coatings will help, but they will have to be inspected frequently because of the frequent depressurization.

        In conclusion, it would be a bad idea. The depth limitations of current deep submersibles are not caused by the pressure hull, but instead by more practical considerations like transport and life support. See http://www.unols.org/committees/dessc/replacement_ HOV/new_hov_brochure.pdf [unols.org] (PDF link).
    • Re:Buildings (Score:2, Interesting)

      by kcelery (410487)
      But when your house is on fire, those tiny fibres within the concrete block would lost strength when temperature go around 200 C. When the temperature went higher, combustion of the fibre would weaken concrete strength further.
      • Re:Buildings (Score:5, Interesting)

        by Velk (807487) on Friday May 06, 2005 @04:20AM (#12449368)
        How do you know that ? The article makes no mention of what the fibres are actually made of, let alone what their temperature response is. And how would they catch on fire if they are inside the concrete ? It would have to crack open to expose them to oxygen before that could happen, presuming that they are even flammable in the first place.
    • Re:Buildings (Score:4, Interesting)

      by Dead Kitty (840757) on Friday May 06, 2005 @05:23AM (#12449496)
      buildings that bend and shift better under harsh weather conditions such as wind and rain

      Although it's good for a structure to have some flexibility under periodic loading (earthquakes, winds, etc.), the U of M article mentions applications like expansion joints and roads. In an expansion joint, the component is expected allow displacement to reduce pressure on other parts. Just think about a simple bridge with 2 expansion joints on both ends. Temperature changes will cause the bridge to expand/contract. Rigid joints on either end would prevent the structure from deforming freely so there would be a lot of added stress. The amount of force to resist this expansion/contraction is huge, (Any second year civil engineering students can back me up with some numbers) thus the need for expansion joints. The joints themselves aren't doing any significant load-bearing.

      Compare this to a building where much of the structure is supporting vertical loads (gravity). Imagine if a column was made from this stuff, nothing could depend on it for structural support due to its inability to resist deformation. So everything this column (or beam) is trying to hold up comes tumbling down. Just look at that video where the beam completely bends under the load.

      Flex in structures is good in hurricanes and stuff, but it doesn't do much good if it can't even hold itself up.
      • Re:Buildings (Score:3, Insightful)

        by Dayflowers (729580)

        The joints themselves aren't doing any significant load-bearing.

        Yes indeed. It is as you say.

        Imagine if a column was made from this stuff, nothing could depend on it for structural support due to its inability to resist deformation

        This however is not quite true. The article mentions the fact that this new cement is more flexible and resistent to bending. As it happens, cement is very very weak in such circumstances. The beams in a structure are made of Reinforced Concrete (RC) because of this.The

    • I'd expect that buildings and roads made of this stuff would be better than normal concrete in earthquake zones. Though thats just a hunch
    • Having lived through a couple of major earthquakes I can share you excitement. I doubt though the buildings well be able to shift and bend like rubber, in other words it might not be obvious visibly but as long as they don't crack that'll help. I wonder though if the flexible concrete has a wider range of resonant frequencies, because if the earthquake or a strong wind hits one of those frequencies then the structure will easily fail.
    • Re:Buildings (Score:4, Interesting)

      by CastrTroy (595695) on Friday May 06, 2005 @08:30AM (#12450053) Homepage
      This will be very useful in Canada for sidewalk and maybe even roads. Which are constantly cracking due to freezing and thawing. Not that they ever replace the sidewalks, but now they wouldn't have to replace them because they wouldn't get cracked so much.
    • by jellomizer (103300) *
      As the buildings are washing up and down while the sea stays as steady as a rock.
  • Roads? Hah (Score:5, Funny)

    by nounderscores (246517) on Friday May 06, 2005 @03:06AM (#12449152)
    How about a concrete jumping castle?
  • Roads (Score:5, Insightful)

    by Rosco P. Coltrane (209368) on Friday May 06, 2005 @03:07AM (#12449158)
    Michigan roads must make the perfect test cases for this stuff

    Except that roads crack because water infiltrates under the surface and freezes over. I don't know many material, even 500x stronger concrete, that can withstand the force of expanding freezing water.

    I think the material is more targeted toward seismic-proof constructions.
    • flexible Roads (Score:5, Interesting)

      by nounderscores (246517) on Friday May 06, 2005 @03:11AM (#12449167)
      Maybe a flexible road may not be able to stop the water penetration, but might be able to return (or be pounded) back into its original shape? A small crack stays small, even after many ice expansion cycles, rather than turning into a massive pothole?
    • freezing water (Score:5, Insightful)

      by Soulfarmer (607565) * on Friday May 06, 2005 @03:13AM (#12449178) Homepage Journal
      If the material won't bend/stretch at all, it might shatter, this new elastic concrete supposedly kand bend at least a little, so it could withstand the freezing expanding water. At least I think that the freezing expansion is not enough to stretch the new concrete to it's limits.
    • Re:Roads (Score:3, Insightful)

      by myowntrueself (607117)
      "I don't know many material, even 500x stronger concrete, that can withstand the force of expanding freezing water."

      Its flexible.

      It doesn't need to withstand the force, it gives a little.
      • It doesn't need to withstand the force, it gives a little.

        Supertramp - Give A Little Bit Lyrics
        Roger Hodgson & Rick Davies
        --
        Give a little bit (of your tensile strength)
        Give a little bit (of your tensile strength) of your love to me
        Give a little bit (of your tensile strength)
        I'll give a little bit of my love to you
        There's so much that we need to share
        Send a smile and show you care
        I'll give a little bit (of your tensile strength)
        I'll give a little bit (of your tensile strength)
        So give a little bit (of y
    • Re:Roads (Score:3, Interesting)

      by hal2814 (725639)
      "I think the material is more targeted toward seismic-proof constructions." You mean like jigsaw-puzzle-shaped bricks? (Real geeks will get the reference.)
    • Not to mention, aren't roads paved with a non-concrete material? I'm pretty sure the stuff that is poured into housing foundations is not the same as the stuff they use on the road. as a non-scientific explanation, I often see pavement applied steaming hot, which is kind of a tar like stuff. I only see cement poured from those giant trucks and it never seems hot when poured.

      • Re:Roads (Score:2, Insightful)

        by indy_Muad'Dib (869913)
        your thinking of Asphalt.

        the reason the roads go to hell in a few years is because of the way asphalt is designed and manufactured. if they were to use concrete instead the roads would last 5x longer but cost 2x as much.

        your local government (the one who is in charge of maintaining the road systems in your area) only wants to see temp fixes now, they dont care that if they pay more the roads will still be in great shape in 40 years, they wont be in office then. let the next guy take the blame.

        the
    • by QMO (836285)
      Pretty much any textile handles repeated freezing/thawing cycles just fine.
      The ice-cube trays in my freezer haven't cracked yet, either.
      It is the inflexibility of the material that causes it to crack when the shape is changed.
  • by LemonFire (514342) on Friday May 06, 2005 @03:08AM (#12449160) Homepage
    I remember reading an article that talked about differenct concrete compounds, for example they had made a spring out of concrete.

    -- Error: SIG not found.
  • by wcitech (798381) on Friday May 06, 2005 @03:16AM (#12449200)
    why? because nobody makes the first jump. (shameless matrix refrence)
  • by Red Pointy Tail (127601) on Friday May 06, 2005 @03:18AM (#12449207)
    Doesn't say in the article, but wouldn't this be useful in making buildings that would fare better in absorbing the shocks of an earthquake, instead of crumbling down?
    • Agreed. That's the first thing I thought of. Flexible concrete sounds like a God send for CA.

    • Would it make a better material for building elevated highways and bridges? It needs to tolerate both weak and strong vibrations (small cars and trucks) all day and night. It needs to be water-proof that cracks don't become serious issue, either.
    • The problem with tall buildings is that they do have a certain amount of flexibility, which allows them to sway in an earthquake. The worst case scenario is when the building sways at the same frequency as the earthquake. Then the amplitude gets higher and higher until the building falls down. You're better off having an intelligent vibration dampening system by having a computer automatically move a large weight around near the middle of the building.
  • by Your Pal Dave (33229) on Friday May 06, 2005 @03:18AM (#12449208)
    this one can be solved with bending - Bender Bending Rodriguez [wikipedia.org]
  • by Kelerain (577551) <avc_mapmaster@hotma[ ]com ['il.' in gap]> on Friday May 06, 2005 @03:21AM (#12449219)
    Why not link to the source at the U of M News Service:

    U-M researchers make bendable concrete [umich.edu]

    Technocrat.net [technocrat.net] had this article [technocrat.net] earlier today, and without the extra advertising.

    interesting stuff!
    • To me, the most interesting point is that this material is being tested as a replacement for expansion joints. This would allow more bridges to be paved with concrete instead of being covered by asphalt.

      Michigan is in fact the ideal place to test this stuff. We have

      1. Two seasons, winter and road construction.

      2. State government that neglects roads and bridges until past the point of needing repair.
      See recent news stories about chunks of concrete falling down on traffic under freeway overpasses, etc.
    • A real civil engineering paper on this
      http://www.engineeredcomposites.com/publications/ 2 005-2006/Keoleian%20J%20Infra%20Systems%25 [engineeredcomposites.com]
      I've read over this, and it gives loads of info, but more for the CE, and as an ME student I'm looking for its Youngs Modulus, Tensile strength, cyclic lifespan. And I know they have real numbers for at least two of those, the pic physOrg uses is a UTM, a familiar machine.
  • Michigan roads must make the perfect test cases for this stuff, and I look forward to their improvement.

    Does anyone else here hate highways that are made with concrete? They have them here around Salt Lake with asphalt segments every now and then. Every time I go from concrete to asphalt I realize just how much quieter the car is and smoother the ride feels. It's almost painful to go back to concrete.

    I guess concret must have some advantage if it's used all over, but it seems like asphalt is better for r
    • Re:Concrete Roads (Score:5, Interesting)

      by inflex (123318) on Friday May 06, 2005 @03:29AM (#12449248) Homepage Journal
      Concrete roads are far more resiliant to wear than asphalt/tar roads, this means (generally) less repair work. This is a major factor when you're dealing with a massive arterial system.

      Overall concrete roads and asphalt tend to work out the same in terms of costs (over a period of years), concrete being more expensive to lay but lower repairs and vice-versa for asphalt.

      • Re:Concrete Roads (Score:5, Insightful)

        by inflex (123318) on Friday May 06, 2005 @03:36AM (#12449261) Homepage Journal
        I forgot to note that the "noise" that you're suffering is from the grooving they put into the concrete road. Without this grooving people would be crashing everywhere when it starts raining from aquaplaning (even the smoothest asphalt road will not be as slippery as a wet smooth concrete one).

        Paul.
      • Re:Concrete Roads (Score:5, Informative)

        by TheFlyingGoat (161967) on Friday May 06, 2005 @04:03AM (#12449328) Homepage Journal
        There's an alternative they're trying out in certain areas of Wisconsin. It's basically asphalt, but with a very high rubber content. They grind old tires into the asphalt. The net result is that it costs about the same to lay, and it can "heal" itself to some degree. The main concern is how safe it is when completely frozen, which is why it's only being tested in certain sections of freeway.

        If it does prove to be a viable material to replace basic asphalt, it'll be great for Wisconsin drivers... we deal with slippery roads all winter then road construction in the spring, summer, and fall. If this can at least eliminate pothole patching, it'll pay for itself many times over.
      • by StormyWeather (543593) on Friday May 06, 2005 @04:40AM (#12449409) Homepage
        I see 150 year old brick streets in a lot of towns still. Seems like that's a pretty good building material for slower traffic too :).
    • I live in Pennsylvania, which has the second worst roads in the country. I can tell the difference between asphalt and concrete.

      Concrete is usually smooth, but noisy.

      Asphalt has tends to get potholes from people just spitting on it. And from the "unique" weather we get in Pennsylvania, although New York, Ohio, Maryland, and the Virginias don't have a problem, with similar weather patterns.

      They lay nothing but asphalt here and yes, when it is freshly laid, its nice and smooth, but it is the worst solution
    • In Brussels, they just put a new kind of concrete instead of asphalt on one of the bussiest highway stretches. The manufacturor claims ith will hold maintenance-free for... thirty years.
    • Re:Concrete Roads (Score:5, Interesting)

      by RipTides9x (804495) on Friday May 06, 2005 @05:42AM (#12449547) Journal
      Concrete was the first material that was used in the construction of mass use roadways back in the early days of the automobile as asphalt hadn't been discovered yet. Theres a very good chance that the concrete roads you drive on today were laid back in the 40s and early 50s. But concrete was always expensive to use, and required extensive preperation of the ground in order to pour it. So it was a slow and tedious proces, and not many cities could not afford to have more than one crew going at a time.

      When it was discovered that Asphalt, a by-product of oil refining, could be mixed with a small sized aggregate *gravel* and basically smooshed ontop of any roughly prepared surface to create a roadway, well that was the end of using concrete. Most concrete projects were abandoned overnight and roads started being laid at a fraction of the price and at triple the speed.

      The one caveat is that in Northern Areas it was discovered that asphalt roadways were not holding up as long as their concrete breathern. Many asphalt roads were having to be torn up and replaced every other year due to extensive freeze damage. Many cities went back to using concrete for their roads, until better techniques of preparing the roadbeds were discovered. Which were to compress and smooth the roadbed as much as possible, then lay a barrier layer of aggregate *gravel* on top of that to help with drainage and settling, then to finally slope the finished road from the middle to the edges for increased water run-off.
      • Re:Concrete Roads (Score:3, Interesting)

        by srmalloy (263556)

        The one caveat is that in Northern Areas it was discovered that asphalt roadways were not holding up as long as their concrete breathern. Many asphalt roads were having to be torn up and replaced every other year due to extensive freeze damage. Many cities went back to using concrete for their roads, until better techniques of preparing the roadbeds were discovered. Which were to compress and smooth the roadbed as much as possible, then lay a barrier layer of aggregate *gravel* on top of that to help with

  • by zeromemory (742402) on Friday May 06, 2005 @03:26AM (#12449235) Homepage
    The article fails to state whether the ductility of the concrete results in elastic (returns to its original shape when load is relieved) or plastic (stays in the shape you bent it) deformation.

    One would hope for the former, since structures made out of this material may look strangely 'bent' over time if it readily undergoes plastic deformation.

    And one last note: is this material going to be more cost-effective than steel?
  • Yes but... (Score:5, Interesting)

    by qualico (731143) <worldcouchsurfer.gmail@com> on Friday May 06, 2005 @03:28AM (#12449243) Journal
    ...can it withstand the impact of a jet airplane?
    And is it safe to inhale the fibers if said airplane makes a big ol' mess?
  • by Anonymous Coward
    even if you replaced 2% of the volume with vacuum, you could only make it 2% lighter

    how the hell do they come up with this 40% figure?
  • The architects, contractors, and construction workers of the Petronas towers in Kuala Lumpur simultaneously shout, "D'oh!"
    • Re:A little too late (Score:5, Interesting)

      by zeromemory (742402) on Friday May 06, 2005 @03:56AM (#12449313) Homepage
      The architects, contractors, and construction workers of the Petronas towers in Kuala Lumpur simultaneously shout, "D'oh!"

      From what I remember of watching a documentary on the construction of the Petronas towers, the primary concern of the engineers was the compressibility of the concrete -- each floor has to withstand the weight of the numerous floors above it. Flexibility was the least of their worries.

      Furthermore, the two towers are located on a relatively 'soft' foundation -- they essentially 'float' on sea of soft land. The towers aren't anchored to the bedrock. Additionally, the bridge that connects the two towers is designed to allow the towers to move towards and away from each other. Thus, the towers stabilize each other and are quite flexible. According to the documentary, if you watch the water in the upper-level toilets on a windy day, you'll see it swooshing around.
      • Re:A little too late (Score:2, Interesting)

        by rwjyoung (674310)
        I didnt see the documentary you mention, but I was a civil engineer and I was in Kuala Lumpur when the towers were being built. The rumour was that one tower was built on the bedrock and the other tower was built on clay. From what we experienced of the geology under Kuala Lumpur I would say this was quite feasable. They had different teams of contractors building each tower, One French and one German (I think) and held a race on which tower went up the fastest. The tower on the bedrock won as the other tow
  • ...I believe the technical term for this is "Gray Rubber".
  • Stone bends, too (Score:3, Informative)

    by Zog The Undeniable (632031) on Friday May 06, 2005 @04:08AM (#12449338)
    The columns of some cathedrals - built before people understood roof trusses - are slightly but definitely bent if you sight along them. The percentage strain is very low, so they don't crack.
  • transparent concrete? I seem to recall something about that in /.
  • by Ice_Hole (87701) on Friday May 06, 2005 @04:53AM (#12449429) Homepage
    How much does this road bend, also what kinda of deformation would we see from traffic. The current roads currently get grooves in them. But make a road that actually felxes, wht kind of effect would that have on the surface of the road? This to me would mean MORE maintaining the road, not less.

    Also, what effects would this have on gas mileage of vehicles. If the road was givein way a little as say a semi or large vehicle was driveing over the road, to waht degree would it "sink" into the road? Would you be wanting to run more air pressure in the tires of the vehicle on these types of roads, to compensate for the flex inherant in this road? And over time, what effect would this have on gas. Another valuable resource.

    Also, adding fibers into a road, could effect it's traction. Current roads, are rather random. If (through wear) all these fibers were to orientate themselves one way would this effect the grip these roads provided? Also, now does this fiber react after years of abuse, and oil contamination? If oil were to cause these fibers to swell, or if they were to absord it, I would imagine it would have negative effects.

    But what the heck, it may just work. Imagine, no ccracks in the slab of your home anymore. All for only a few side effects (and probably 3x the cash).

    - Ice_Hole

    • How much does this road bend, also what kinda of deformation would we see from traffic. The current roads currently get grooves in them. But make a road that actually felxes, wht kind of effect would that have on the surface of the road? This to me would mean MORE maintaining the road, not less.

      I think you'll find that the grooves you see are only on asphalt roads. Concrete roads don't get them. Asphalt gets soft when it gets hot, so the cars can sink in a little bit. Concrete roads never get soft. I supp
  • I wonder if this stuff could be used to make buildings more invulnerable to earthquakes. If the foundations and a couple of lower levels were flexible, maybe the building would just wobble rather than shaking itself to bits - the equivalent to putting suspension in a car?
  • The article doesn't mention anything about the stresses this concrete can take. It just says it looks exactly like concrete and cracks less.

    I don't think this kind of concrete is the kind builders would want to make lower-level walls of very tall buildings with. Sure it can handle tensile stresses very well and is extremely flexible, but how will this "concrete" react to compressive stresses? Flexible concrete means less force is required to make it buckle and warp.

    Will this concrete be appropriate for
  • ?? I think this will have a great impact on space building, reading about crazy plastic/concrete/steel mixtures of materials in sci-fi and you will see.

    This could be the start of pour your own space home!

    rar.
  • If you read the article, you may realise that the point here is that the US lags the rest of the developed world in using engineered cement composites. Back in dead tree days, Scientific American had an interesting article on how restrictive building codes and fear of litigation was causing the US to lag behind in road and building construction because more modern materials could not be used.
    This results in higher build and repair costs for roads and bridges and explains the poor maintenance of many US high
    • construction, but scaled composites, USA company, has done some rather innovative work. Space ship one, voyager, ...

      Innovative is not always practical. Building construction is about cost. Steel reinforced aggregate is still the least expensive in most applications. Especially when you can pour at 5AM and 24 hours later pull your forms off 3000+ PSI material.

      I know a company in Georgia that puts up chicken coops using a robot. They erect a jig, the robot sprays and trims a foam form and then sprays concre
  • by Senor_Programmer (876714) on Friday May 06, 2005 @05:30AM (#12449508)
    because the concrete is thinner, not because the concrete is lighter. This discerned from RTFA. We poured a pad for a picnic pavilion at the yacht club using concrete that is reinforced with polyethylene fibers. It allowed us to pour a large pad that will not crack without having to use tiebacks. Which brings to mind something I've often wondered about...

    With concrete, when it's pre or post stressed in compression, it's much less likely to crack. Traditionally this is done by tensioning the steel prior to pouring or tensioning cable or rod 'tiebacks' after partial curing. Now this is very nice but... It should be possible to engineer a fiber that will shrink as it ages and bonds well as an aggregate. If the shrink time could be matched up reasonably well with the cure time of the concrete it would simplify many types of construction.
  • The look... (Score:5, Funny)

    by skander (43037) on Friday May 06, 2005 @05:58AM (#12449595) Homepage
    World Trade Center made of bendable concrete: 262m $US
    747: 5m $US
    Razor Blade to hijack plane: 2.95 $US

    The look on Osama's face as the plane bounces off the building: priceless.

  • There have been boats built out of concrete for years, they aren't a new phenomenon, the hull has some flexibility. Replacing the steel reinforcing with fibres is an interesting development.

    To find out more...
    http://www.google.co.uk/search?hl=en&q=ferrocement +boat&btnG=Google+Search&meta= [google.co.uk]

  • 500 times more resistant to cracking

    The bridge is 40 percent lighter than traditional concrete

    he ECC is 37 percent less expensive,

    consumes 40 percent less energy,

    produces 39 percent less carbon dioxide

    findings are based on the assumption that ECC lasts twice as long as regular concrete, a reasonable assumption given the known information, but it must be confirmed through further study.

    What exactly does "500 times as flexible" mean? How can a bridge be lighter than concrete?

    Read the last point c

  • by CrazyWingman (683127) on Friday May 06, 2005 @08:32AM (#12450066) Journal
    Ok, so they say it looks exactly like concrete. Despite the fact that I don't think it matters what roads look like (as long as their not bright yellow, requiring new traffic markings), I really think looks matter even less in this case.

    The real question is, how does it feel? What kind of texture does the outside of it have? Does it have some grit to it, or is it perfectly smooth? If the latter case, can a grit be ground into it, and will it hold that gritty shape? Smooth-surface roads are a Bad Thing (tm).

    Yes, I know it says that they have already used it in roads, but both examples listed describe small patches of the stuff. Even further, in the replacement of the expansion joints on the bridge, this stuff is replacing steel, which is also slick. Even with the other road patch they talk about, in most places I've lived, that means that it probably replaced a large steel plate.

    Just wondering. Maybe I need to go try to find the actual UofM site that describes it, rather than this news article. :P
  • For road use... (Score:5, Interesting)

    by Transcendent (204992) on Friday May 06, 2005 @08:36AM (#12450087)
    ...will it have the same (or better) coefficient of friction than normal concrete? Sure it might not crack, but if your tires don't stick to the road, then you're going to have more problems...
  • by psychonaut (65759) <psychonaut@nothingisreal.com> on Friday May 06, 2005 @08:45AM (#12450145) Homepage
    "Tiny fibres" embedded in the concrete? Reminds me of the tiny fibres of asbestos, which get stuck in people's lungs and cause cancer. Are we looking at a possible health risk here as this bendable concrete crumbles off unmaintained buildings, and is gradually eroded off highly used roads?
  • RTFA (Score:3, Insightful)

    by MikeDawg (721537) on Friday May 06, 2005 @09:06AM (#12450272) Homepage Journal

    I was two sentences into this article when I thought about the condition of Michigan's roads. I was already thinking about a post on how ironic it was that it was the Univ. of Michigan that developed this concrete, and look at the road conditions. As the article noted, it is perfect conditions here in Michigan to test this new concrete.

  • Here's a streaming video! [umich.edu]

    (And here's the original article [umich.edu] from the Univ. of Michigan)

    *already starts to feel guilty about the /. effect* :-(
  • by scovetta (632629) on Friday May 06, 2005 @10:09AM (#12450692) Homepage
    We can finally make people more comfortable when we toss them off a bridge into the ocean!
  • by gone.fishing (213219) on Friday May 06, 2005 @08:23PM (#12458759) Journal
    A couple of years ago my interest in boating caused me to start looking into composites. Eventually I settled on pretty pedestrian epoxy and fiberglass cloth due to it's reasonable cost, strength, and overall characteristics. I built my first boat and found it more than rewarding.

    Learning about composites and their characteristics was far more interesting and rewarding that I would have ever imagined. How and why they do what they do is just cool - and trying to understand what the best composite for the best application is can sometimes involve a lot of research (and even then you will here different opinions from different experts - who are all naturally trying to sell you something).

    Fero-cement boats are actually kind of common and have been in use for many years. While heavier than a comparible fiberglass or steel boat, they have some advantages (easier to make complex curves than steel for instance). Over years a "concrete" boat (and all cement based products are in their own right composites) wear out and require more and more maintenence to keep them seaworthy. One of the hardest things to engineer is the fact that you have to deal with expansion and contraction (this is why roadways and sidewalks have seams in them).

    Flexible concrete that only contains a small percentage of interlinking fibers could revolutionize concrete for boat building purposes. While I am allowing myself to dream here a little bit, I think it is possible that in time concrete could become the matterial of choice to build large ships!

    In larger ships the added weight of concrete would not add so much mass that it would really reduce the effiency of the ship much at all and construction could be a whole lost faster (especially if mass produced in molds).

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