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(bright music)
(transition wooshes)

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- [Narrator] Recycling crushed
concrete course aggregate

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generates significant
amounts of fine aggregate.

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The Texas Department of
Transportation traditionally uses

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20% of this recycled crushed
aggregate to replace sand

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in Class P concrete,
saving taxpayer dollars

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while reducing the impact
on the environment.

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Working closely with TXDOT and
private sector contractors,

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researchers at the
University of Texas Center

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for Transportation Research
studied the effects

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of increasing the use of
recycled crushed concrete

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in aggregate mixtures.

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- TXDOT has always been a promoter

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of use of recycled materials in concrete

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and one of the restrictions
that we had was limiting

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how much recycled concrete
fine aggregates we allow

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and so we wanted to do some research

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to see if we could really
determine what is the limit

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of how much recycled fine
aggregate is feasible.

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- Our goal of this project was to increase

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the use of recycled
concrete as an aggregate

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in concrete pavements and by doing so,

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increase the sustainability
without sacrificing performance.

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- So this was a combination
of both laboratory

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and field testing.

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There was a large component
of laboratory evaluations

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of all the materials that we collected

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and we're doing the studies
in the lab to see, you know,

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where should we be focusing
on mix designs in the field.

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- Once we proved the concept in the lab

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and we went out to the
field, we worked very closely

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with TXDOT to identify
a site, and that is I10,

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but it was the eastbound
frontage road in Sealy, Texas

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that amounted to about a half a mile

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of continuously reinforced
concrete pavement,

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and since that pavement was constructed,

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we've gone back four different times

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to evaluate performance.

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- So far, the research has
shown that we could probably go

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up to about 70% replacement
without much of an issue

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comparing to our current specifications.

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- What that provides in terms
of benefit is not needing

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to use as much naturally
mind or process materials,

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and in terms of the
public, the biggest benefit

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is that we're being more
sustainable as an industry.

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- We could see some benefit
and some bid reduction

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by using recycled crush
concrete more often

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in higher percentages.

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Again, a benefit for
department is to realize

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some of those potential cost savings

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by using recycled materials.

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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.