Backfilling With Lightweight
Aggregate
Contractors enjoy practical experience of a
different application with TXI's rotary-kiln lightweight aggregate.
Staff - Texas Contractor, 5/16/2005
In late summer 2001, Brent Vilhauer, vice president of operations at
TRI DAL Utilities Limited, was awarded a project with underground tanks
requiring pea gravel at the Dallas/Fort Worth International Airport. He
needed an alternate granular bedding and backfill material that was cost
effective and available in large quantities as an alternative to pea
gravel and was impressed with what he learned about TXI's rotary-kiln
lightweight aggregate. During the process of seeking engineering and
budget approval for the use and purchase of the lightweight aggregate,
two planes flew into the World Trade Center in New York City and all
work on the DFW project was abruptly halted.
Fast forward to the following summer in Waxahachie where TRI DAL was
a subcontractor working on the Cardinal Glass Manufacturing Plant, the
leading manufacturer of residential coated glass. The facility consists
of a 210,000-square-foot plant on a 30-acre site where workers add
Lo?² coatings to raw glass used in residential windows. Vilhauer
remembered TXI's rotary-kiln lightweight aggregate and ordered 500 cubic
yards for use as embedment for utilities.
"This is an alternate product that's cost effective for trucking due
to its weight and will eventually, in my opinion, take the place of pea
gravel," said Vilhauer.
Other contractors on the job site (SME Electrical, TD Mechanical and
Hidalgo Industries) noticed the aggregate's superior qualities in terms
of reduced labor and material cost and inquired about using it in their
own project applications. Product orders snowballed and more than 2,300
cubic yards total was eventually used in approximately nine miles of
underground electrical and mechanical work, including embedment for
buried electrical cables, water and sewer lines; and backfill for grade
beams. Of particular note, the aggregate was used to backfill large
underground electrical duct banks, measuring 2 feet to 7 feet wide by 4
feet to 7 feet deep, that run electrical conduit under the building's
foundation.
"TXI lightweight aggregate is a wonderful material," said Richard
Kampen, project manager and supervisor with Design Structures LLC of
Prairie du Sac, Wisconsin, which was the general contractor on the
Cardinal Glass project. "The ease of use and the simple compaction
effort of the aggregate made the installation process faster and thereby
saved time and money."
Kampen explained that his work crew didn't need to bring in
compacting equipment and was able to make backfill in 2-foot increments,
instead of the standard 8-inch lifts that required compacting before
placing additional layers. This dramatically reduced the amount to time
required to make backfill.
Cost-Effective Choice
Kampen says an added bonus with lightweight aggregate was the cost
savings on the price of the material compared to pea gravel, which has
been historically used as a backfill and embedment material in Texas
utility construction. Combine the purchase savings with the reduced
labor and equipment costs and contractors familiar with lightweight
aggregate are quick to mention that cost effectiveness is a big factor
in their decision to use lightweight aggregate.
"Not only is the lightweight aggregate cheaper and easier to
install, it's a quality product that performs as well or better for
bedding and backfill than materials presently being used," said Larry
Lyon, foreman with the MEP Projects Division of TD Industries. Lyon
estimates that his company has used about 2,000 cubic yards of the
material in the past three years as backfill and embedment on various
construction projects.
To date, engineers and superintendents on more than 20 utility
construction projects in Texas have successfully used lightweight
aggregate as an embedment, drain field and backfill material. Some of
these completed projects include Lowe's Hardware Center in Marshall;
John Eagle Toyota in Lewisville; Mims Creek Wastewater Plant in
Fairfield; and Sonoma Basin Utilities in Ennis.
Produced from natural shale and clay, TXI rotary-kiln lightweight
aggregate offers strength and long-term performance for a variety of
construction uses. For more than 20 years, rotary-kiln lightweight
aggregate has been used in the petrochemical industry as insulation
under hot asphalt tanks to prevent the surrounding soil from moving due
to temperature extremes.
