(logo whooshes)
- (Narrator) Finding the best mix design for Texas roads
is the main goal of this project.
In ways never before evaluated,
researchers from the University of Texas at El Paso
are assessing TxDOT's current mix designs and guidelines
for using recycled asphalt pavements and shingles,
as well as additives.
- This project started looking at,
the title of it is "A Balanced Mix Design,"
but the goal here was to look at performance,
to measure the mix.
In the past, the design process was looking
into volumetrics, pavements, either failing,
rutting or cracking.
Those are the primary modes of failure.
So we wanted to run a test, these two tests,
on the mix, whether it was rutting,
using the Hamburg-machine or whether it the cracking,
using the overlay test to see how it would perform.
- 95% of the mix, asphalt mix is aggregate components.
We started focusing on that part of it.
Most of the previous studies, they were focusing
on the 5% which is the binder.
We changed the gradation for the purpose
of allowing more room so that we can add
more binder into the mix.
So by allowing more binder, now you have
a more flexible mix.
And a more flexible mix would not crack as easily.
- Initially took a super pave mix design,
which is kind of our go-to mix design.
And we added in cracking criteria,
which we hadn't really done in the past.
We have this balance mix design,
obviously as your cracking resistance goes up,
your rutting resistance probably goes down
because it's driven by binding.
So this is to find that kind of happy median
and help develop a specification
so that we can work towards a more performance-based
and say, "If you meet this cracking criteria
"and you meet this rutting criteria,
"we don't really care as much about what you put in here."
- [Prof. Nazarian] The cost of construction
would go up a little bit, but if the road lasts
one more year that pays for itself hundred times.
- (Narrator) For more information,
and to find the publications for this project,
please visit the TxDOT Research Library
at the link shown below.