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I
n the past I have written
four training contrac-
tor programs and have
noticed with the current
construction “best prac-
tices” and evolving tech-
nologies they have tended
to become quite complex
regardless of the sector.
One technique I have used with considerable
success involves addressing the most com-
mon 10 deficiencies or omissions with regard
to construction product installation and com-
missioning. (If this can be accomplished you
can effectively eliminate most of the common
deficiencies.)
In the process of inspecting interlocking
concrete pavement inspections you should
determine that the pavement installation is in
fact interlocking concrete and not decorative
stamped concrete. Although they are relatively
rare you may also encounter brick or granite
pavement installations. (Both are outside the
scope of this article.)
In the case of interlocking concrete pavers we
know from experience that the most common
deficiencies for residential installations are
related to:
• Insufficient depth of base materials: aggre-
gates and bedding sand.
• Incorrect placement and cutting of the con-
crete pavers.
• Failure to install edge restraints, or incorrect
installation of restraints.
• Failure to completely fill the joints between
pavers with properly specified joint sand
• Failure to compact the entire installation to
adequate levels.
Technically, although often neglected there is a
technical requirement for the pavement surface
to achieve a 2% “berm” which is not normally
visible to the naked eye. This is specified for
structural integrity under loading and to ensure
proper drainage.
Another common deficiency is failure to allow
for the growth of trees and other vegetation
adjacent to the paver installation over the long
term. (There are products available to prevent
growth underneath the concrete pavements,
such as root barriers or landscape fabric).
Two common deficiencies that occur but are
technically not installation related.
• Weed growth.
• Settlement of pavers around downspouts,
near walls or the perimeter of the pavement
installation.
These deficiencies are typically due to loss of
joint sand for one reason or another caused by
freeze/thaw cycles, drainage patterns and the
effect of loading by vehicles. Weed growth,
which is avoidable and preventable, is not
normally considered an installation deficiency;
however, stabilizing polymeric sand can prevent
loss of joint sand from exposure to environmen-
tal conditions and insects.
Obviously, loads differ dramatically between
driveways and walkways/patios. The “rule of
thumb,” however, is to apply the same instal-
lation techniques used for driveways when
installing walkways, patios and other paver
installations.
Also you may see occasions were concrete pav-
ers in the walkway will meet asphalt driveways
and this typically requires a proper “interface”
connection in the form of some material that can
withstand expansion and contraction.
As a rule I don’t recommend removal of pavers
to determine base material thickness. This can
be time-consuming and it is also very difficult
to re-instate the concrete paver after you have
disturbed the base and pavement installation.
Background: Small element segmental paving
units have been used to construct durable sur-
faces for roadways for over 5,000 years using a
variety of materials such as natural stone setts,
wooden blocks and clay bricks.
Some Roman roads built in this manner were so
well designed and constructed that they are still
in serviceable condition today, and could easily
be used except for the fact that they are more
valuable as tourist attractions.
Segmental “interlocking” concrete pavers (ICPs
as we know them today) were developed in the
Netherlands in the 1950s as a replacement for
clay bricks, which were frequently used to pave
roads and streets. The long established tradi-
tion of segmental paving in Europe resulted in
tremendous growth in the industry and there are
over 500 million m
2
installed annually around
the world.
Building Science Inspection Forum
Interlocking Concrete Pavers (ICP)
By Brian Burton
continued on page 37
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