CONCRETE BLOCK REVETMENTS
Concrete blocks, many of them patented, have various intermeshing or interlocking features
(Figure B-5). Concrete blocks have the advantage of a neat, uniform appearance. Many units are light
enough to be installed by a landowner once the slope has been prepared. The disadvantage is that
interlocking between units must be maintained. Once one block is lost, other units soon dislodge, and
complete failure usually results. A good, stable foundation is required since settlement of the toe or
subgrade can cause displacement of units and ultimate failure. Also, some concrete block revetments
have smooth faces that can lead to significantly higher wave runup and overtopping.
The design requirements for rubble revetments also hold for concrete blocks. In addition, the
concrete must be quality-controlled since standard building blocks deteriorate too quickly. Special
concrete mixes (higher strength) are recommended. Also, blocks should not be used where they may be
stolen or damaged by wave-borne cobbles, ice, or debris.
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