- [Narrator] Some new pavements,
which have cement treated materials,
fail prematurely, experiencing rutting, or cracking.
This project tries to determine why the problem exists
and how to make these specific pavements more reliable.
Researchers with the University of Texas at El Paso
have developed new mixed design specifications
after an extensive laboratory evaluation.
- In Texas, we have several thousand miles
of cement treated pavements with cement treated layers.
And a lot of our districts now are grappling
with issues related to the premature failure,
cracking of the pavements,
and anything that jeopardizes the longevity of our pavement.
- There have been cases where pavements using
cement treated layers had not reached
their predicted pavement life.
And so it was thought that there could be two problems.
One could be either with the cement treated layers
or the prediction using the models.
- [Reza Ashtiani] So the main motivation
that we had for this project was
to look into the current practices that we have
for the design of cement treated layers.
And then we basically we'll look into
how we can improve the current mixture designs
that we have.
- [Wade Blackmon] We actually have quite a bit
of cement treated materials projects
because it's one of the more cost-effective means
of recycling materials or adding strength.
The issue was strength versus cracking.
- There are several issues that contributes
to the cracking failure and issues related to
the longevity of the pavements.
Obviously the first one
is the laboratory mixture design.
If we get the mixture designed wrong
all the dominoes will fall afterwards.
We also looked into other aspects such as fatigue cracking
that we have in cement treated layers
and the way that we looked at it was
we basically looked into development
of a new fatigue performance model.
And we calibrated that over 62 pavement sections
all across Texas, making sure that we consider the diversity
of the climate that we have in Texas
as well as the diversity of the materials that we have.
One of the major outcome of this project
was a refined specification for cement treated material.
In this newest specification
we considered compressive strength, tensile strength,
shrinkage cracking potential,
as well as looking at the durability protocols.
- Some of the main benefits would be
smoother pavements, longer lasting pavements,
which would be a significant cost savings to the public.
So better testing, which is what is suggested
by this new specification, better testing will lead to
longer-lasting pavements, better riding pavements
- [Narrator] For more information,
and to find the publications for this project,
please visit the TexDOT research library
at the link shown below.