Self-healing asphalt | Erik Schlangen | TEDxDelft

Erik Schlangen presents his invention of self-healing asphalt using steel-wool fibers and induction energy.

(Crackling)

(Thud)

(Laughter)

(Microwave beeping)

You probably all agree with me
that this is a very nice road.

It's made of asphalt.

Asphalt is a very nice material
to drive on.

But, not always,
especially not on days as today,

when it's raining a lot.

Then you have a lot of splashing
water on the asphalt,

and especially if you ride
your bicycle and cars pass you,

then that's not very nice.

Also, asphalt can create
a lot of noise.

It's a noisy material,

and if we build roads,
like in the Netherlands,

very close to cities,
then we would like a quiet road.

We have solutions for that.

The solution for that is
to make roads out of porous asphalt.

Porous asphalt material
that we use now

in most of the highways
in the Netherlands,

it has pores, and water
can just rain through it,

like you see in this image.

So all the rain water
will flow away to the side,

and you have a road easy to drive on,

so no splashing water anymore.

Also the noise will disappear
into these pores,

because it's very hollow,
all the noise will disappear,

so it's a very silent road.

It also has disadvantages, of course.

A disadvantage of this road
is that reveling can occur.

What is reveling?

You see that in this road
the stones at the surface come off.

So what actually happens,
first you get one stone,

then several more,

and more, and more, and more,

and then they --

I will not do that.

(Laughter)

But they can damage your windshield,

so you're not happy with that.

Finally, this reveling can also lead
to more and more damage

like you see in the next image,

sometimes you can create
potholes with that.

(Microwave beeping)

Hah, it's ready.

Potholes, of course,
can become a problem.

But we have a solution.

Here you can see how the damage
appears in this material.

It's a porous asphalt, like I said,

there is only a small amount
of binder between the stones,

and this binder,
due to weathering, due to UV light,

due to oxidation,
this binder, this bitumen,

the glue between the aggregates
is going to shrink.

And if it shrinks, it gets microcracks,

and it delaminates from the aggregates,

and then if you drive over the road

you kick out the aggregates,
which we just saw here.

To solve this problem,
we thought of self-healing materials.

If you can make these materials
self-healing,

then probably, we have a solution.

So what we do is use steel wool,

used to clean pans,
like you see in the picture,

and the steel wool we can cut
into very small pieces,

and these very small pieces,
we can mix into the bitumen.

Then you have asphalt with
very small pieces of steel wool in it.

Then you need a machine,
like you see here,

that is used for cooking,
an induction machine.

Induction can heat especially steel,
it's very good at that.

And then what you do is you melt --

you heat up the steel,
you melt the bitumen,

and the bitumen will flow
into these microcracks,

and the stones are again
fixed to the surface.

Today I used a microwave,

because I cannot bring the big
induction machine to heat on the stage,

so I microwaved, it's a similar system.

So I put the specimen in,
which I'm going to take out

to see what happened.

I need my gloves again.

This is the specimen coming out now.

We have such an industrial
machine in the lab,

to heat up the specimens.

We tested a lot of specimens there,

and then the government,
they actually saw our results,

and they thought,

Well, that's very interesting.
We have to try that.

So they donated to us
a piece of highway,

400 meters of the A58,
close to Vilssingen,

where we had to make
a test track to test this material.

So that's what we did here, you see
where we're making the test road,

and then, of course,
this road will last several years,

without any damage,
that's what we know from practice.

So we took a lot of samples
from this road,

and we tested them in the lab.

So we did aging on the samples,

did a lot of loading on it,

healed them with our induction machine,

healed them, tested them again.

Again broke them, healed them,
several times we can repeat that.

So actually the conclusion
from this research is that

if you go on the road every
4-years with our heating machine--

this is the big version we have made
to go on the real road --

if you go on the road every 4-years

we can double the service life
of this road,

which, of course,
saves a lot of money.

To conclude, I can say
that we made a material

using steel fibers,
additional steel fibers,

and using induction energy,

to really increase
the service life of the road,

even double the service life,

really save a lot of money
with very simple tricks.

And now you're of course
curious if it also worked.

So I still have the specimen
here, it's quite warm.

Actually it has to cool down first,

before I can show you
that the healing works,

but I will do a trial.

Let's see --

Yeah, it worked!

Thank you.

(Applause)