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(swooshing)

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- [Announcer] The Texas
Department of Transportation

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has sponsored research with
modified asphalt binders

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in the laboratory and on Texas roads.

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This work resulted in
a catalog that is used

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by district engineers during construction.

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While previous research focused

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on new road construction,

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TxDOT realized a catalog was needed

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specifically for overlays
where new asphalt

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is laid over existing pavement.

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The Texas A&M Transportation Institute,

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working with TxDOT,

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has developed a catalog
designed specifically

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to address binder asphalt
procedures on existing roadways.

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- We do a lot of overlay construction,

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which is on the top of existing pavement

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that may be a flexible pavement

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or a concrete pavement.

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And we did not have a catalog that says,

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okay, this is the most
appropriate binder grade

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that maybe you need to start with.

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- Most of the work we're doing in Texas

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or the whole nation is asphalt overlays.

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So there are big differences between

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asphalt overlay and the new construction.

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One of the major differences is

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existing crack for asphalt overlays.

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The existing crack will shorten

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the asphalt overlay pavement life.

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- So in this research,
obviously, this has been

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a continuation of other projects

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and the information collected

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from over the years, right?

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Because there is lot of
overlay that is constructed,

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and we did want to see what
is the grade of the binder.

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- We look at multiple aspects

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of this binder selection catalog.

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We look at from, asphalt binder, itself.

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We also look at asphalt
mixture, and then we also look

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at pavement performance
simulation based on models.

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- So around 2,700 different
simulation run from TxME

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which is a TxDOT mechanical
and empirical guide,

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kind of in a software that
was used to run the scenario.

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A lot of laboratory test was also done

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to validate some of
these, you know, cases.

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- Most importantly, we build
multiple filter test sections

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around the state to validate
anything from, you know,

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from the lab binder test,

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from mixture test result,

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also from the model simulation.

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So that's given us the
confidence to present the

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the final binder selection catalog.

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- The key finding obviously
is the grade that we are

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traditionally selecting
for a new construction

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may not work for overlay
because of the thickness

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of the overlay, which is, you know,

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thinner than a new construction obviously.

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And also the grade that is most likely

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we need to go better grade

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than in a new construction.

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- Using right binder for asphalt overlays.

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it will make the pavement
last much, much longer.

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And that means save millions dollars

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of taxpayer money every year.

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- We'll have a better
selection of the material

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which is basically on this
particular is a binder grade

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so less maintenance,

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longer life,

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and less disturbance in
the general public use

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of the, you know, pavement.

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- 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.