Erik Schlangen: A "self-healing" asphalt

167,318 views ・ 2013-02-12

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Translator: Joseph Geni Reviewer: Thu-Huong Ha
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(Hammer)
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(Laughter)
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(Microwave beeps) (Laughter)
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You probably all agree with me
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that this is a very nice road.
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It's made of asphalt,
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and asphalt is a very nice material to drive on,
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but not always, especially not on these days as today,
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when it's raining a lot.
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Then you can have a lot of splash water in the asphalt.
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And especially if you then ride with your bicycle,
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and pass these cars, then that's not very nice.
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Also, asphalt can create a lot of noise.
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It's a noisy material,
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and if we produce roads like in the Netherlands,
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very close to cities, then we would like a silent road.
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The solution for that is to make roads
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out of porous asphalt.
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Porous asphalt, a material that we use now
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in most of the highways in the Netherlands,
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it has pores and water can just rain through it,
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so all the rainwater will flow away to the sides,
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and you have a road that's easy to drive on,
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so no splash water anymore.
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Also the noise will disappear in these pores.
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Because it's very hollow, all the noise will disappear,
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so it's a very silent road.
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It also has disadvantages, of course,
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and the disadvantage of this road is that raveling can occur.
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What is raveling? You see that in this road
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that the stones at the surface come off.
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First you get one stone, then several more,
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and more and more and more and more,
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and then they -- well, I will not do that. (Laughter)
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But they can damage your windshield,
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so you're not happy with that.
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And finally, this raveling can also lead to more and more damage.
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Sometimes you can create potholes with that.
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Ha. He's ready.
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Potholes, of course, that can become a problem,
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but we have a solution.
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Here you see actually how the damage appears in this material.
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It's a porous asphalt, like I said, so you have only
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a small amount of binder between the stones.
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Due to weathering, due to U.V. light, due to oxidation,
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this binder, this bitumen,
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the glue between the aggregates is going to shrink,
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and if it shrinks, it gets micro-cracks,
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and it delaminates from the aggregates.
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Then if you drive over the road, you take out the aggregates --
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what we just saw here.
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To solve this problem, we thought of self-healing materials.
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If we can make this material self-healing,
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then probably we have a solution.
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So what we can do is use steel wool just to clean pans,
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and the steel wool we can cut in very small pieces,
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and these very small pieces we can mix to the bitumen.
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So then you have asphalt
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with very small pieces of steel wool in it.
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Then you need a machine, like you see here,
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that you can use for cooking -- an induction machine.
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Induction can heat, especially steel; it's very good at that.
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Then what you do is you heat up the steel,
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you melt the bitumen,
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and the bitumen will flow into these micro-cracks,
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and the stones are again fixed to the surface.
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Today I use a microwave because I cannot take
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the big induction machine here onstage.
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So a microwave is a similar system.
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So I put the specimen in, which I'm now going to take out
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to see what happened.
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So this is the specimen coming out now.
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So I said we have such an industrial machine in the lab
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to heat up the specimens.
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We tested a lot of specimens there,
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and then the government, they actually saw our results,
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and they thought, "Well, that's very interesting. We have to try that."
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So they donated to us a piece of highway,
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400 meters of the A58, where we had to make
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a test track to test this material.
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So that's what we did here. You see where we were making the test road,
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and then of course this road will last several years
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without any damage. That's what we know from practice.
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So we took a lot of samples from this road
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and we tested them in the lab.
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So we did aging on the samples,
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did a lot of loading on it, healed them with our induction machine,
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and healed them and tested them again.
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Several times we can repeat that.
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So actually, the conclusion from this research is that
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if we go on the road every four years
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with our healing machine -- this is the big version
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we have made to go on the real road --
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if we go on the road every four years
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we can double the surface life of this road,
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which of course saves a lot of money.
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Well, to conclude, I can say
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that we made a material
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using steel fibers, the addition of steel fibers,
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using induction energy to really
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increase the surface life of the road,
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double the surface life you can even do,
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so it will really save a lot of money with very simple tricks.
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And now you're of course curious if it also worked.
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So we still have the specimen here. It's quite warm.
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Actually, it still has to cool down first
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before I can show you that the healing works.
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But I will do a trial.
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Let's see. Yeah, it worked.
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Thank you.
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(Applause)
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