Researchers Make Bendable Concrete

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.

Comments

Buildings

[antivoid]

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...

Re:Buildings

[Dayflowers]

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 concrete behaves well enough in compression, but has very little tensile strength and so it will crack very very soon. In fact, in a normal structure, there will always be some cracks. Calculations are made in order to keep these fairly small though ( below 0.3mm is what the EC2 recomends, but it depends on what the purpose of the structure is and its environment ).

Since they say this new composite cement weights 40% less and has alot more tensile strength, I imagine that it is less rigid and thus can more easily have some problems in columns under horizontal loads (e.g. earthquakes) but that is not serious prolem. You just need slightly bigger sections for your columns, and the 40% weight reduction will cetainly compensate for that. Besides, you will only really have to worry about such problems if your columns have a low height/column-width ratio. You should also expect a bit more problems with the deformations of beams, but that can be solved with a little more steel to compensate.

Worry not, the deformation of the columns under axial loads is NOT serious. Cement in such circumstances has a maximum deformation around 0.35%. It has hardly any significance for common applications.

please note, I AM a Civil Eng. Student :)

Roads

[Rosco P. Coltrane]

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.

freezing water

[Soulfarmer]

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.

Earthquake-proof buildings

[Red Pointy Tail]

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?

Plastic or Elastic Bending?

[zeromemory]

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?

Re:Concrete Roads

[inflex]

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:Remember asbestosis?

[King_of_Prussia]

Why is this modded up?

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..."

Only possible problems I see..

[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.

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