(soft music)
- [Narrator] Continuously reinforced concrete pavement,
or CRCP, is known for its long-term performance
and cost-effectiveness.
Recently, fixed CRCP sections in Texas
have shown stress points not usually seen,
with segmentation of slabs at transverse cracks,
under the wheel paths.
It appears that steel placed at mid depth of the slab,
can increase warping stresses.
The Texas Department of Transportation,
working with Texas Tech Center,
for Multidisciplinary Research in Transportation,
investigated this type of distress,
and developed steel designs, to combat the issue.
- TxDOT used to use CRCP
up to 10 inch, 11 inches thickness,
when the traffic was not that heavy.
But now, due to the, I guess,
increase in heavy truck traffic,
TxDOT is using thicker slabs,
in their pavement, up to around 15 inches.
And what we found out in this research project,
is that when the slab is say, up to 10 or 11 inches,
it works okay.
Placing the steel at the middle depth is okay.
However, when the thickness was, say 12, 13, 14, 15 inches,
placing steel at the middle depth,
there are some problems.
- We like to consider concrete pavement
as a low maintenance type of payment.
And this distress was kind of eating into that idea.
And so we wanted to have this research,
so that way we could improve already,
or improve more of our concrete pavement performance
than what we already have.
And so this was kind of the basis for this research.
- So what we did was,
we actually selected four projects:
one in Dallas District, El Peso,
San Antonio, and Waco districts.
So we installed various gauges in the concrete and steel,
in those four construction projects.
Then we analyzed the data to understand the behaviors.
- The bulk of the research
was looking at different orientations of reinforcing steel,
and monitoring stresses and strains in the pavement,
as we modified the steel design.
And so that was the bulk of the research,
was done monitoring field trial sections.
- The major finding is that if we place steel
a little bit higher than the middle depth,
it changes the pavement behavior substantially,
and then it really minimizes any distresses.
- Right now we have drafted a revised standard
for continuous reinforced concrete payments,
that incorporate the findings of this research project,
where we are now adjusting the location
of the reinforcing steel within the slab.
And so we're trying to push some additional research,
to monitor some of our other concrete pavement sections,
so that way we could get a better understanding
of those behaviors,
and potentially modify that steel design,
which could lead again,
better performance and cost savings down the road.
So we're actively trying
to push some additional research
that stems directly from this research project.
- [Voiceover] For more information,
and to find the publications for this project,
please visit the TxDOT Research Library,
at the link shown below.