Page 347 - Masonry and Concrete

Retaining Walls

for tensile strength and concrete or
masonry for compressive strength and cor-
rosion protection.
CONCRETE Before steel and concrete were
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invented, retaining walls were built of
brick or stone and used simple gravity to
hold the soil in place. These gravity retain-
ing walls rely on the mass of the wall to
provide resistance to sliding and overturn-
ing and on the form of the wall to reduce
the weight of the soil as its height
increases (Figure 10-2). The wedge-shaped
wall requires a lot of material, particularly
for tall retaining walls. The structure is so
stable, however, that it can be built of
unreinforced brick or even of dry-stacked
CONCRETE BLOCK
stone laid without mortar. A mortared
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brick gravity wall relies on the weight of
the masonry and the bond of mortar to
units to resist the overturning motion of
the earth embankment. A dry-stacked
stone gravity wall relies on its weight, fric-
tion between the stones, and the physical
interlocking of the stones for its strength.
Gravity retaining walls are not used much
any more, but for low retaining walls or
terraces in a garden, there is nothing more
charming than the rustic look of dry-stack
stone. Gravity retaining walls can still be
BRICK
fairly economical for small installations,
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but dry-stack stone is labor intensive, and
the taller the wall the less cost-effective
this type of construction will be.
One of the newest developments in the
concrete masonry industry is the dry-
FIGURE 10-1
stacked, interlocking concrete block retain-
Cantilever retaining walls. (from Newman, Morton, ing wall system. Referred to as segmental
Standard Cantilever Retaining Walls, McGraw-Hill,
New York). retaining walls, a variety of proprietary

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