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(logo whooshes)

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(train chugs)

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- [Narrator] In several TxDOT districts,

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asphalt binders used in
chip seal construction

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are required to contain
a specific percentage

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of tire rubber.

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Testing for tire rubber
content can be done

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in the materials and test division lab

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using x-ray fluorescence technology,

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but the Texas Department of Transportation

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and researchers with the Center
for Transportation Research

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want to bring XRF testing to the job site.

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- The current process requires
the district to take a sample

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and send it to MTD.

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MTD can run the test,

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the x-ray fluorescence test

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and then give the district the results.

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That requires a time lag.

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- We've been measuring it here at MTD

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for quality assurance samples,

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quality that those are supplier samples

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and for project samples.

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However, by the time we get the sample

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and get the testing done, in some cases,

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if it's a seal coat project,
the project is done.

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So that was the intent is to
give the district the tools

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to be able to run the
test as soon as possible.

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- These x-ray fluorescence
guns are portable,

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so you can either have
them in the district lab

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or if you want to, you can
take it out on the job site

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on the side of the road and get a sample

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from the distributor or the tanker truck

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and then in a couple of
minutes, you can run the gun

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and get the answer.

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You get on the side of the road

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before anybody actually even sprayed

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any of the asphalt on the ground

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to ensure that you had the
right tire rubber content.

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- First, we purchased three different,

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new equipment

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to distribute the three district labs

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and a lot of training happened

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in the district facilities,

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trained them how to use the equipment

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and it also included looking into

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using the equipment in the field.

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- We created a spreadsheet.

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It's a global spreadsheet
for all of the guns

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that we bought, so a person doesn't have

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to generate calibration curves.

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They're all in the spreadsheet already.

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All a person has to do
is perform the analysis,

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take the results from the gun
and plug it into a spreadsheet

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where they have chosen their specific gun

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and their specific supplier and binder

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and it tells 'em what the
tire rubber content is.

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- Asphalts with tire rubber
are typically charged

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at a premium, so they are
a little bit more expensive

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'cause they're modified
versus unmodified asphalts

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and this gives us the tool to make sure,

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if we're asking for 5%, are we getting 5%?

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The bottom line is that we
are able to apply the spec.

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We're able to make sure
that we're meeting the spec

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and we're getting what we're asking for.

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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.