(bright music) (transition wooshes)
- [Narrator] Recycling crushed concrete course aggregate
generates significant amounts of fine aggregate.
The Texas Department of Transportation traditionally uses
20% of this recycled crushed aggregate to replace sand
in Class P concrete, saving taxpayer dollars
while reducing the impact on the environment.
Working closely with TXDOT and private sector contractors,
researchers at the University of Texas Center
for Transportation Research studied the effects
of increasing the use of recycled crushed concrete
in aggregate mixtures.
- TXDOT has always been a promoter
of use of recycled materials in concrete
and one of the restrictions that we had was limiting
how much recycled concrete fine aggregates we allow
and so we wanted to do some research
to see if we could really determine what is the limit
of how much recycled fine aggregate is feasible.
- Our goal of this project was to increase
the use of recycled concrete as an aggregate
in concrete pavements and by doing so,
increase the sustainability without sacrificing performance.
- So this was a combination of both laboratory
and field testing.
There was a large component of laboratory evaluations
of all the materials that we collected
and we're doing the studies in the lab to see, you know,
where should we be focusing on mix designs in the field.
- Once we proved the concept in the lab
and we went out to the field, we worked very closely
with TXDOT to identify a site, and that is I10,
but it was the eastbound frontage road in Sealy, Texas
that amounted to about a half a mile
of continuously reinforced concrete pavement,
and since that pavement was constructed,
we've gone back four different times
to evaluate performance.
- So far, the research has shown that we could probably go
up to about 70% replacement without much of an issue
comparing to our current specifications.
- What that provides in terms of benefit is not needing
to use as much naturally mind or process materials,
and in terms of the public, the biggest benefit
is that we're being more sustainable as an industry.
- We could see some benefit and some bid reduction
by using recycled crush concrete more often
in higher percentages.
Again, a benefit for department is to realize
some of those potential cost savings
by using recycled materials.
- [Narrator] For more information
and to find the publications for this project,
please visit the TXDOT Research Library
at the link shown below.