Tensar® Biaxial (BX) Geogrids Case History

Tensar® Biaxial (BX) Geogrids Case History
Montgomery County Road – Cherryvale, KS
Contractor:
Vasco Brown
Montgomery County Road &
Bridges Department
Designer/Engineer: Carl Peoples
Contech Construction Products
Owner:
Montgomery County, KS
Installation Date:
November 2003
Geogrid Type:
BX 4100
Montgomery County Road Supervisor Vasco Brown
didn't think someone else's sand shortage was his
problem—until a contractor's dump trucks started
tearing up one of his roads. A recent highway project
in the southeastern Kansas county required hundreds
of cubic yards of sand that had to be imported by
rail and then transported to the construction site by
heavily laden trucks. Unfortunately for Brown, the
road from the railhead was built across a 300-foot
long section of weak subsoils that were incapable of
supporting this type of traffic.
"The road had problems all along," Brown says. "We
had cut down the grade and applied a new base
An example of the poor road conditions Montgomery County
drivers endured.
several years earlier, but that approach didn't solve
the problem. With it breaking up again, we weren't
sure what to do."
Brown was certain traditional construction methods
would not solve the ongoing settlement and
cracking problems. He started to research other
strategies for dealing with difficult subgrades and
came across a product sheet for Biaxial (BX)
Geogrids manufactured by Tensar Earth
Technologies. He sought feedback on the product
from other professionals in the field and eventually
asked Carl Peoples, a Sales Engineer with Contech
Construction Products, Inc., to take a look at the road.
"It was crumbling apart," Peoples recalls. "The
dump trucks had completely ruined the surface.
Rutting was forcing the base out along the edges to
the right and left of the roadway. To me, it looked
like an ideal application for Tensar BX Geogrids."
Brown decided to use the road, which serves a busy
industrial park, as a test to evaluate the
effectiveness of geogrid technology. If the
reinforcement held up under ongoing truck traffic,
he anticipated being able to use the material on
other projects in Montgomery County.
A rural road with a 300-foot long section of weak subsoils that
were incapable of supporting the traffic of heavily laden
construction trucks.
Tensar® Biaxial (BX) Geogrids Case History
Continued
In November 2003, he organized a design,
instructing his crew to undercut the roadway to a
depth of 11 inches. They then leveled the subgrade
and rolled out Tensar BX4100 Geogrid. To achieve
optimal reinforcement, each roll of geogrid was
overlapped 12 inches and then covered with 11
inches of aggregate.
"We were able to do everything without any new
equipment," Brown says. "So this was a simple deal
for us."
Paving on the repair area was postponed until spring
to allow additional settlement to occur. In March
2004, Brown's crew returned to the site, cut down
the aggregate by three inches and capped it with
new hotmix.
After more than a year of heavy use, Brown reports
that the portion of the road rebuilt with BX Geogrids
shows no sign of pavement failure – not even
reflective cracking – despite demanding vehicle and
truck traffic. "It's real promising so far. Nothing I see
concerns me, but I want to keep checking it over the
next couple of years."
Nearby Wilson County has also decided to give BX
Geogrids a try. "I told them how it's working for us,"
Brown says, "and they decided to use it on a recent
project. Like us, they figured you've really got
nothing to lose if you've got a really bad road."
While Brown will continue to monitor the railhead
site, the initial results have been positive enough
that the Montgomery County Road and Bridges
Department has decided to use BX Geogrids along a
500-foot section of another problem-prone road.
Brown thinks the County is likely to find additional
uses for the product since it is easy to install and
appears to hold up well under very demanding
real-world conditions.
®
BX Geogrid with aggregate before final paving.
The portion of the road in Montgomery County rebuilt with
geogrid.