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(logo swooshes)

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- [Narrator] The road
construction industry

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is a leader in sustainability.

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Recycled materials,

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especially Reclaimed Asphalt
Pavements, or R.A.P.,

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and Recycled Asphalt Shingles, or R.A.S.,

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dramatically reduce road building costs,

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while being environmentally friendly.

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But getting the right formulations

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in order to achieve good
engineering performance

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is a challenge, thanks
to all the variables.

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To make needed improvements,

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a synthesis project was performed

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by the Texas A and M
Transportation Institute.

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Designed to revise TxDOT's
standards and specifications.

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- Sustainability efforts
motivate the increased use

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of recycled asphalt materials
in asphalt pavements.

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So we are trying to increase the amount

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of reclaimed asphalt pavement or RAP,

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and/or recycled asphalt shingles or RAS

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in our asphalt pavements,

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for both economic and
environmental benefits.

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- Traditionally at TxDOT we've used

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a lot of recycled material.

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The problem is, is when
we use recycled material

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we don't have a good way to quantify

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how much binder we're actually getting.

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- [Amy] We have to make sure
that we're going to engineer

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the combination of materials that's unique

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for every set of virgin
materials, aggregate and binder,

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and recycled asphalt materials,

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as well as any additives.

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And so part of that focus of engineering

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the combination of materials,

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is to understand how much
old-aged stiff binder

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you're getting off your RAP and RAS.

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- [Travis] On a national standard,

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what you, most people use,

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is either solvent
extraction or ignition oven,

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which is essentially it's
a very, very hot oven.

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The problem with that is

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if you put something in there,

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it will burn it off regardless.

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If you put it in solvent,

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it will pull all of the asphalt out.

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But it could be in the
middle of that rock, right,

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that you're removing this binder,

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and we're accounting for
it as if it's actually

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contributing in the mix;

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and most the time it's not.

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Across the state,

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what we're finding is
anywhere from 16 to 96%

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of your recycled binder is actually usable

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in recycled asphalt pavements.

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On average, it's 40 to 45%,

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and then we just call it a
good average and go with it.

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You have to account for
the climatic conditions,

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how long it's been out there,

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so we really do need a test to quantify

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how much is in there.

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- We did come up with a recommendation

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of using 75% recycled binder availability

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when a few conditions are met.

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What they should do is try to get ahold of

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a few of their RAP sources

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and extract and recover
the binder would help,

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to know how stiff their binder is

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in the recycled asphalt pavement.

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And that that can help
them know, in mixed design,

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should I reduce the binder availability

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from a hundred percent, which
is what's currently assumed,

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down to 75%, for example.

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And I think that alone,

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would go a long way to making sure

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that we have enough effective
binder from the old material,

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the RAP, and from the new virgin binder,

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to coat and bind our aggregates together.

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- [Narrator] For more information

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and to find the publications
for this project,

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please visit the TxDOT Research Library

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at the link shown below.