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SPACING REINFORCEMENT IN ARMOR UNITS
To present two methods of spacing reinforcing bars during the construc-
PURPOSE:
tion of armor units. This is not a recommendation for either method but only
information for field offices' consideration.
Rubble mound breakwaters are used extensively throughout the world
BACKGROUND:
to provide protection from the destructive forces of storm waves. In some
locations, adequate size and quality quarrystone is not available, so specially
shaped concrete armor units are required for the primary cover layer of the
breakwater. Even when quarrystone is available, the concrete units may be the
least costly alternative. The major advantage of these shaped concrete armor
units is their high stability coefficient which permits the use of lighter weight
armor units. Many different types of blocks have been developed, varying in
geometric shape from simple rectangular
or cubic blocks to more complicated
shapes such as the "dolos" (dolosse
is plural). See Figure 1. This
unit was developed by Eric M.
Merrifield of South Africa but
it is free of patents restric-
ting its use. The dolos also
has a relatively high stability
coefficient. Dolosse were used
on the Manasquan Inlet Jetty
Project (in New Jersey) which
was completed in 1982. The
contractor, providing dolos
armor units for this project,
developed a spacer which was
very successful in reducing
Figure 1. 40-Ton Dolosse in Place
production time while
U.S. Army Corps of Engineers, Coastal Engineering Research Center, Kingman Building, Fort Belvoir, VA 22060
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