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.
Springs made out of concrete (Score:3, Interesting)
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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.
flexible Roads (Score:5, Interesting)
Re:Buildings (Score:2, Interesting)
Yes but... (Score:5, Interesting)
And is it safe to inhale the fibers if said airplane makes a big ol' mess?
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: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: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:Buildings (Score:5, Interesting)
Re:Concrete Roads: How about brick (Score:4, Interesting)
Re:A little too late (Score:2, 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.
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 highways.
The article is essentially saying that, at last, someone is prepared to experiment with ECCs in the US on a small scale following a test in a difficult area. Meanwhile, advantage has been taken of these materials in the Far East for a number of years.
This is important because in many ways the US is becoming depressingly conservative. It is no longer a world leader in innovative building. Ford and GM have just seen their shares reduced to junk status as the Japanese and Daimler-Chrysler increase their share of the US auto market. And the whole IP/copyright thing is basically about trying to protect what you have rather than innovate and create new markets. If this little experiment is a sign that someone is getting brave enough to risk trial lawyers (my client tripped over a kerb as a result of using this unproven concrete technology...) perhaps it's a green shoot.
"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.
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:Roads (Score:3, Interesting)
Re:Buildings (Score:4, Interesting)
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)
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.
Comment removed (Score:5, Interesting)
Re:Buildings (Score:2, Interesting)
Re:Concrete Roads (Score:3, Interesting)
"Discovered". Feh. Until the cities were willing to cough up the money to prepare the roadbed correctly [ket.org], a practice [unc.edu] which had been in use two millennia earlier, but which fell out of use because of the lack of civic incentive to build [unrv.com] and maintain good roads.
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).