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(intense music)

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- [Narrator] Asphalt seal
Coat is an essential tool

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in protecting existing roads

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and making sure they maintain
adequate skid resistance.

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But there are times where the
coated layer fails prematurely

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because of poor durability

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or when the seal coat is not compatible

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with the previously laid road.

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The Texas Department of Transportation

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working with the Center
for Transportation Research

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investigated ways to gauge
expected seal coat performance

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and use that research as a
tool for similar projects.

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- Chip seals are a very important pavement

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preservation technique that are used

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across the state of Texas.

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There's nearly $300 million
of chip seal work that is done

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on an annual basis to
preserve our pavements

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and also to ensure a safe riding surface.

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Now, the way chip seals work
is that there's a thin film

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of asphalt binder or
emulsion that is placed

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on the pavement surface
and aggregates one layer

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of aggregates are placed
on top of it typically,

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and these aggregates need to glue

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with the asphalt binder
surface underneath it.

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So the purpose of this
project was to make sure

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that we have a tool by which to assess

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whether or not the
aggregates are bonding well

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with the asphalt binder
surface underneath it.

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- Seal Coat is something that
we do across the entire state.

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It's our mainstay, our bread and butter

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for preserving the life
of our infrastructure.

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And we realized that we really didn't have

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any performance based
testing similar to hot mix

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for seal coat.

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So this research project
was looking at developing

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a test that measured some performance.

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We didn't really have
anything specifically in mind

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when we did this.

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We just knew that we wanted
a performance measure

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for seal coat.

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- As a part of this
project, we developed some

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very simple tools that
can be used by districts

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or contractors to assess
the quality of the bond

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between the aggregate and
the emulsion or the binder,

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and as next steps,

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we would like to see
districts use these tools

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or this equipment and run these tests

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on a routine basis as a part of

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their annual seal coat
program to assess the quality

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of the materials that are
being used in the field.

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- We did a lot of lab testing

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and we developed some testing
that we think shows promise

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that needs to be further
developed in the field.

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So we had to do something that
we could write, number one,

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gain some kind of performance measure

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and then two that was repeatable.

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So we think we've identified a few tests

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that could move forward.

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Now we just need to move forward

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with implementing those or
furthering the research.

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- The next steps in this
project is to integrate

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the findings into the
specifications for chip seals.

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There are specifications
embedded in the chip seal spec

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right now for asphalt and for aggregate.

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and this would tie the two
together to measure compatibility

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of the two.

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- If we have a performance
based aspect of these seal coat,

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we're gonna be able to check to make sure

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that this provides a safer
surface for the traveling public

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and secondly, it's gonna be a cost saving.

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- Typically, seal coats
have a serviceable life

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about seven years

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and if you are able to
extend the serviceable life

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or avoid premature
failures, that translates

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into a lot of money saved.

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- [Narrator] For more
information and to find

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the publications for this project,

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please visit the Tex.Research Library

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at the link shown below.