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TECHNICAL
ICPs are typically the size of a house brick,
approximately 200 x 100 mm in plan and
80 mm in thickness for structural pavements
and 60 mm for pedestrian areas not subject to
traffic. ICPs have been used in many industrial
and commercial applications including airports,
ports and factories.
Design Principles: Three aspects of interlock
must be achieved when installing ICPs: vertical,
rotational, and horizontal. Vertical interlock is
achieved by the transfer of loads to surround-
ing units through the fine, hard sand located
in the joints between the pavers. Rotational
interlock is maintained by the thickness of the
pavers placed closely together, and by the edge
restraints that are firmly anchored around the
perimeter of the pavement surface.
Horizontal interlock is primarily achieved through
the use of various laying patterns that disperse
forces from braking, turning and accelerating
vehicles. (Testing has shown that herringbone
patterns offer greater structural capacity and
resistance to lateral movement and are rec-
ommended for vehicular traffic.) Stable edge
restraints are essential to maintain horizontal
interlock when the units are subject to repeated
lateral loads.
Design Considerations: The evaluation of four
factors will determine the pavement thickness
and other materials used in construction. These
include:
• Soil Sub-Grade Strength - The strength of
the soil sub-grade has the greatest effect
in determining the total thickness of the ICP
installation. Compaction of the soil sub-grade
is critical to the performance of ICP systems.
• Pavement Material - The type, strength and
thickness of all available paving materials
should be established. Crushed aggregate
bases or stabilized bases used in highway
pavement construction are generally suit-
able under interlocking concrete pavers. Most
provinces and municipalities have material
and construction standards for these bases.
• Environmental Considerations – As moisture
in the soil or base increases, the load bearing
capacity of the soil or the strength of the base
decreases. Extreme temperature variations
and the effects of freeze\thaw cycles also
effect the pavement.
• Traffic – Traffic causes wear over the pre-
dicted 30 year pavement life is dependent on
the weight of the vehicles and volume.
When properly installed, ICPs provide a durable
and “forgiving” system which has the ability
to distribute vehicle loads to adjacent pavers,
bedding sand, compacted aggregates and soil
sub-base (all of which are contained by edge
restraints).
ICP’s require care in their design, specification,
construction and maintenance. These durable
pavements can last a minimum of forty years
when installed correctly and are frequently
specified for commercial and industrial applica-
tions for the following reasons:
• Lowest cost for service life.
• Excellent resistance to traffic with minimal
rutting or deformation.
• Resistance to abrasion, freeze/thaw cycles
and deicing salts.
• Immediately ready for traffic upon installation
with no delay for curing.
• Ease of access to underground utilities.
• Reduced maintenance and repair costs
• Increased safety for pedestrians
Advantages
Very low maintenance costs.
Pleasing appearance that can be achieved using
the wide range of shapes and colours available.
Brian Burton is a regular columnist for Glass
Canada magazine and is currently serving on the
CSA’s Fenestration Installation Technician Certi-
fication Program Committee. Brian is a Research
and Development Specialist for exp* and can be
reached at
or visit
(*the new identity of Trow Associates
Inc.)
The most common deficiencies for residential installations are related to insufficient depth of base materi-
als, incorrect placement and cutting of the pavers, failure to install edge restraints, or incorrect installation
of restraints.
Other common deficiencies include failure to completely fill the joints between pavers with properly speci-
fied joint sand and failure to compact the entire installation to adequate levels.
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