Mortarless masonry
takes center field
BESSER CO.
Versatile segmental retaining-wall systems show off their ability
to handle two landscaping challenges
n acknowledged strategy for
success in team sports is having
role players. These “jacks of all
trades” handle whatever is asked, such
as pinch running or playing any infield
position, and they often get their uniforms dirty.
Similarly, segmental retaining walls
handle all the various landscaping
designs some sites throw their way. But
unlike utility infielders who get dirty
sliding into second base or diving after
a ground ball, they maintain a clean,
attractive appearance while playing a
A
role within a landscaping team concept. Two recent sports-facility projects
attest to segmental wall versatility.
A wall in a league of its own
Abner Doubleday didn’t intend
outfielders to run uphill to catch fly
balls when he invented baseball in the
19th century, so Lebanon Valley College
of Annville, Pa., had to do something
about a hillside in the middle of the
site of its planned McGill Field in fall
1997. A major state highway on the
other side of the hill made an earth-
Segmental retaining wall units
form an attractive outfield fence at
Lebanon Valley College’s McGill
Field in Annville, Pa. Michael
Carroll of Binkley & Ober showed
that the cost of the company’s
SRW units would be significantly
lower than cast-in-place concrete
or brick alternatives.
BESSER CO.
sales department at
masonry unit producer Binkley & Ober
in East Petersburg, Pa.
One major cost
involved with these
systems was casting
footings.
Looking at a segmental wall, the
president saw it
would be possible to
have multiple retaining walls—including
an attractive 9-foothigh vertical outBinkley & Ober’s marketing efforts were so successful that the architect
field wall—built at a
used masonry for walkways, dugouts, and even elevated bullpens.
reasonable cost. The
retention system essential.
Versa-Lok system worked as part of a
To blend in with the campus buildsite-improvement team, bringing out
ings, the college president at first wantpossibilities for other site features.
ed a wall made of either precast conMatching split-face units were used
crete or brick, the latter donated by a
for planters, walkways, dugouts, and
longtime benefactor. “They were thinkeven walls for elevated bullpens inteing that was going to save them some
grated into the outfield wall. Seating
costs, but the costs were just astrofor 500 also has a segmental wall as a
nomical,” says Michael Carroll of the
veneer, and the configuration allows
integration of other split-faced masonry units into the walls. The results were
so positive that Derck & Edson, the
landscape architect, used the system for
bleachers and players’ benches at a soccer facility next to McGill Field.
From dump to playing surface
It’s hard to imagine a worse site than
the one Johnson C. Smith University
recently had prepared for a football
and track facility in Charlotte, N.C.
One end borders a highway and
required 30 feet of cut on solid granite,
and another end required 25 feet of fill
on decomposing trash and alluvial soil.
Landscape architects at Hayden
Stanzale helped design a soil-retention
system that included wick drains to
soak up water, a geosynthetic drainage
blanket foundation, and a 30,000square-foot retaining wall.
“Segmental block systems seemed
to work the best because of their ability to function flexibly and to be resistant to the problem of differential settle-
Adaptable system uses interlocking components
ne segmental retaining wall/fence system is turning heads in
the Pacific Northwest due to its simplicity of design, ease of
installation, and versatility. Designed and licensed by Fircrest,
Wash.-based WestBlock Systems, GravityStone normally consists
of three interlocking face, trunk, and anchor/junction components.
Whether consisting of single CMUs in mechanically stabilized
embankment
GravityStone cell
(MSE) applicaconsisting of
tions or multiinterlocking face
ple CMUs for
block, trunk
modular walls,
block, and anchor/junction
the system is
installed in a
block components. Additional trunk
running bond
and anchor/junction units form addipattern, and
tional cells at the base of the wall, which narrows
courses contoward the top, much like a dam.
nect with alignment plugs. The earth-retention system can create tall walls in
combination with geogrid (MSE walls) or without it (modular
walls).
In MSE applications, typically used when import of fill is
necessary, standard face components form a single cell and
combine with geogrid. The use of a single cell can reduce the
geogrid requirement by as much as 70% for economy in walls
15 feet and taller.
For modular cut applications, the contractor assembles face,
O
trunk, and anchor/junction units to form a single cell. For taller
walls, extensions consisting of additional trunk and anchor/junction units form additional cells at the wall base that give the system relative depth, stabilize the soil, and eliminate the need for
geogrid. A typical cell, which mainly owes its depth to the nearly 2foot-long trunk block, is 27 to 32 inches deep, compared with the
typical retaining wall unit’s 12 inches. Gravel is used as structural
fill. The system is designed to reduce excavation costs for cut
applications because the wall structure is relatively narrow.
The wall system’s soil-stabilizing attribute also gives it design
flexibility on sites where further subgrade development, such as
installation of utilities, occurs behind the wall. Using the benefit of
the single cell in MSE applications or the modular design, the
designer can create more space at the top portions of the wall in
the cavity area between the wall and the embankment. Additionally,
since the system allows increased geogrid spacing for MSE walls,
it’s easier to install utilities between layers of geogrid in the reinforced zone of the soil.
The concrete producer can cast the units efficiently. The producer gets the equivalent of 1.5 square feet of product per cycle
with a 32-inch-deep assembly, compared with the typical 1 sf per
cycle with 24-inch-deep units.
For more information about WestBlock System’s GravityStone
wall system, stop by Booth 605 at Masonry Expo 2000 or circle 1
on the reader service card.
THE ALLAN BLOCK CO.
would have been
more expensive, and
with a segmental system the units had the
potential to lean over
the face more than
over the back.”
The cut side of the
site presented other
challenges, with vertical seams of granite
just below the soil
surface that required
blasting, interspersed
E. Dillon & Co., Swords Creek, Va., produced the masonry units for
with soft soil. “When
this retaining wall at Johnson C. Smith University in Charlotte, N.C.
the contractor came in
The units were used for both cut and fill walls.
to put in sheet piles in
order to make a cut,
he couldn’t drive them deep enough,”
ment of the soil,” says geotechnical
Barrier says. So the contractor cast a
project engineer Donnie Barrier of
concrete cut-off trench to hold the
Barrier Engineering. “We wanted to get
sheet piles in place. Two 15-foot sega block with a good batter to it,” he says
mental walls complete the system.
of 12-degree-batter units licensed by
“We looked at putting in different
Allan Block Corp. and produced by E.
foundation systems—piles, caissons—
Dillon & Co. of Swords Creek, Va. “A
but what we didn’t want to do was
cast-in-place concrete retaining system
match rigid and flexible because the
two wouldn’t work together,” says
Barrier. “As soon as we did the groundwork, we were able to start building the
wall right away,” he adds, noting that
with a rigid system, drying out the soil
for a year would have been necessary.
—Don Talend
Publication #J00A015
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