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(logo whooshes)

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- (Narrator) Finding the best
mix design for Texas roads

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is the main goal of this project.

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In ways never before evaluated,

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researchers from the
University of Texas at El Paso

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are assessing TxDOT's current
mix designs and guidelines

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for using recycled asphalt
pavements and shingles,

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as well as additives.

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- This project started looking at,

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the title of it is "A
Balanced Mix Design,"

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but the goal here was
to look at performance,

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to measure the mix.

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In the past, the design
process was looking

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into volumetrics,
pavements, either failing,

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rutting or cracking.

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Those are the primary modes of failure.

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So we wanted to run a
test, these two tests,

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on the mix, whether it was rutting,

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using the Hamburg-machine
or whether it the cracking,

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using the overlay test to
see how it would perform.

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- 95% of the mix, asphalt
mix is aggregate components.

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We started focusing on that part of it.

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Most of the previous
studies, they were focusing

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on the 5% which is the binder.

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We changed the gradation for the purpose

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of allowing more room so that we can add

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more binder into the mix.

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So by allowing more binder, now you have

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a more flexible mix.

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And a more flexible mix
would not crack as easily.

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- Initially took a super pave mix design,

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which is kind of our go-to mix design.

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And we added in cracking criteria,

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which we hadn't really done in the past.

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We have this balance mix design,

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obviously as your cracking
resistance goes up,

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your rutting resistance probably goes down

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because it's driven by binding.

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So this is to find that
kind of happy median

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and help develop a specification

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so that we can work towards
a more performance-based

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and say, "If you meet
this cracking criteria

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"and you meet this rutting criteria,

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"we don't really care as much
about what you put in here."

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- [Prof. Nazarian] The
cost of construction

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would go up a little bit,
but if the road lasts

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one more year that pays
for itself hundred times.

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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.