Researchers Make Bendable Concrete 399
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.
A keyboard? (Score:4, Funny)
Re:A keyboard? (Score:5, Funny)
Re:A keyboard? (Score:5, Funny)
Buildings (Score:5, Insightful)
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)
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.
Re:concrete submarine (Score:5, Informative)
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
Re:Buildings (Score:2, Interesting)
Re:Buildings (Score:5, Interesting)
Re:Buildings (Score:4, Interesting)
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)
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
Earthquake zones (Score:2)
Re:Buildings (Score:2)
Re:Buildings (Score:4, Interesting)
Re:Buildings (Score:3, Funny)
Roads? Hah (Score:5, Funny)
Flying Citadel? (Score:2)
Some doorknob of a kender would steal it.
Roads (Score:5, Insightful)
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)
Re:flexible Roads (Score:2)
Comment removed (Score:5, Interesting)
freezing water (Score:5, Insightful)
Re:Roads (Score:3, Insightful)
Its flexible.
It doesn't need to withstand the force, it gives a little.
Re:Roads (Score:2)
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)
Re:Roads (Score:2)
Re:Roads (Score:2, Insightful)
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
Re:Roads (Score:2)
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.
Re:Roads (Score:2, Funny)
What have Jell-O shots got to do with it?
KFG
Re:Roads (Score:3, Funny)
Don't ask me how to apply that material to roads, though.
Sure as I c'n set a wireless tower in the holler, I c'n say that there a'int no way to freeze the roads south of Virginny!
Springs made out of concrete (Score:3, Interesting)
-- Error: SIG not found.
Re:Springs made out of concrete (Score:5, Informative)
concrete trampoline? (Score:5, Funny)
Earthquake-proof buildings (Score:5, Insightful)
Re:Earthquake-proof buildings (Score:2)
Re:Earthquake-proof buildings (Score:2, Funny)
Highways instead? (Score:2)
Re:Earthquake-proof buildings (Score:2)
Like most of life's problems... (Score:5, Funny)
Origional News Source at U of M (Score:5, Informative)
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!
Re:Origional News Source at U of M (Score:2)
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.
Re:Origional News Source at U of M (Score:3, Informative)
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.
Concrete Roads (Score:2)
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)
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)
Paul.
Re:Concrete Roads (Score:5, Informative)
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.
Re:Concrete Roads: How about brick (Score:4, Interesting)
Re:Concrete Roads: How about brick (Score:3, Informative)
In this town, we have cobbled streets, still going strong from the Middle Ages...
Re:Concrete Roads (Score:2)
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
Re:Concrete Roads (Score:2)
Re:Concrete Roads (Score:5, Interesting)
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)
Plastic or Elastic Bending? (Score:5, Insightful)
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?
Re:Plastic or Elastic Bending? (Score:3, Informative)
True, but the most important factor in this case would be the lower yield strength (LYS), the point at which the transition from elastic to plastic behavior occurs. The article says very little about whether this concrete has a great LYS (deform elastically under everyday stress), or a small LYS (plastically deform even under little stress).
Yes but... (Score:5, Interesting)
And is it safe to inhale the fibers if said airplane makes a big ol' mess?
Re:Yes but... (Score:5, Funny)
No, but because of it's bendability, it can actually dodge incomming plains.
Re:Yes but... (Score:5, Funny)
Re:Yes but... (Score:3, Funny)
What, we're worried now about people crashing Oklahoma into buildings as an act of terrorism?
Re:Yes but... (Score:3, Funny)
Re:Flexon my Marchon (Score:2)
replacing 2% volume reduces weight by 40%? (Score:2, Insightful)
how the hell do they come up with this 40% figure?
Re:replacing 2% volume reduces weight by 40%? (Score:3, Informative)
The fibers are only one part of the improvement. The article also mentions replacing other major components in the concrete, including the bulk aggregate. Presumably the new components are also lighter and would account for the 40% reduction.
Re:replacing 2% volume reduces weight by 40%? (Score:4, Informative)
Re:replacing 2% volume reduces weight by 40%? (Score:2, Insightful)
Re:replacing 2% volume reduces weight by 40%? (Score:3, Insightful)
A little too late (Score:2, Funny)
Re:A little too late (Score:5, Interesting)
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)
This isn't new... (Score:2)
Stone bends, too (Score:3, Informative)
Whatever happened to ... (Score:2)
Re:Whatever happened to ... (Score:2, Informative)
Only possible problems I see.. (Score:5, Insightful)
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
Re:Only possible problems I see.. (Score:3, Informative)
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
Earthquakes (Score:2)
Sliding fibres? (Score:2)
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
Concrete roads? (Score:2)
This could be the start of pour your own space home!
rar.
This is about US engineering conservatism (Score:2, Interesting)
This results in higher build and repair costs for roads and bridges and explains the poor maintenance of many US high
It's not civil engineering or building (Score:2, Insightful)
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
"the bridge is 40% lighter..." (Score:5, Interesting)
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)
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.
Not really new. There are concrete boats. (Score:2)
To find out more...
http://www.google.co.uk/search?hl=en&q=ferrocemen
More statisitics than a soap ad (Score:2, Redundant)
What exactly does "500 times as flexible" mean? How can a bridge be lighter than concrete?
Read the last point c
Looks, eh. How does it Feel? (Score:4, Interesting)
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.
For road use... (Score:5, Interesting)
Possible health risks (Score:3, Interesting)
RTFA (Score:3, Insightful)
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.
The site owners are going to kill me but... (Score:3, Informative)
(And here's the original article [umich.edu] from the Univ. of Michigan)
*already starts to feel guilty about the
Concrete galoshes... you mean cement overshoes? (Score:3, Funny)
composites are almost as interesting as computers (Score:3, Interesting)
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).
Re:Forget architecture. (Score:2)
So it's a dead concrete?
Re:Forget architecture. (Score:2, Funny)
Concrete is just the next logical step.
Ob Simpsons (Score:2)
Re:Remember asbestosis? (Score:3, Informative)
tends to form particles 0.5 to 1.4 microns in diameter, which is the range in which any paticulate matter is lung damaging and carcinogenic in nature. Asbestos is not mutagenic; any particles that form mainly in that size will cause lung cancer. It is a strange twist of fate that asbestos fibers disintigrate to particles that size, but it has nothing to do with fibers in general or their chemistry.
Re:Remember asbestosis? (Score:5, Insightful)
Fiber reinforced materials have been around for years. Carbon and glass fiber reinforced polymers are used in many everyday applications without harm. The problem with asbestos was its crystal structure and cleavage planes, which enabled it to break down into very small (micrometer scale) fibers that were easily inhaled.
The above comment is about as insightful as saying "Cotton fiber? That seems eerily reminiscent of asbestos, better not wear clothes!" or "AIDS medicine? Wasn't thalidomide also orally available in pill form? Better not give it to pregnant women..."
Re:Concrete roads? (Score:2)
One area where you can't use asphalt is on raised runways, like the elevated sections of freeways. Concrete might be more brittle, but its greatest quality lies in its resistance to compression. Unlike concrete, asphalt can't support tons of weight, so people don't make load-bearing structures out of asphalt.
This material might
Re:Concrete roads? (Score:2, Interesting)
you use concrete for the bearing construction and put asphalt on the road... thats how they do over here in Switzerland
Re:Concrete roads? (Score:2)
Dynamite, Anyone? (Score:3, Informative)
I don't think buildings made out of this stuff will survive a large enough explosion. Besides, concrete is really easy to break apart and chip (hence why you need to use rebar frames for serious construction), so just whacking away with chisel-tipped jackhammer should work for small jobs.
Re:Like those portable cement dwellings (Score:2)
That would be Elton John's house, then?
Re:But do states really want good roads? (Score:4, Interesting)
Improved roads reduce fuel consumption, and also pollution. Maintaining bad roads is also costly, removing funds that can be used for other purposes, and can be itself polluting. In the long term, everyone gains, and cost is reduced. It's almost a free lunch.
So long as we are talking about upgrading existing roads, not building a massive new network of roads, I don't see how anyone can be displeased by this.