Landscaping & Design Ideas

Interlocking pavements are considered flexible pavements.  Loads are distributed through the base by surface contact and interlocking through the various materials, including the paver, jointing sand, bedding sand and base.  The base, which is a crushed limestone or recycled concrete, protects the subgrade from deforming under loads.  When a load reaches the soil layer,  it is distributed across a wide area so that the soil does not deform or rut.  Knowing what kind of loads will be used ensures that the proper amount of base material is installed at the time of installation.  Whether it be pedestrian traffic on a backyard patio, or the weight of heavy machinery at a shipping dock, the right base depth ensures that the pavers distribute the load properly to the subgrade below.

Interlocking pavers spread loads across the base, and can move with minor movements in the base without cracking.  This gives pavers an advantage over asphalt or concrete, which can crack if the base moves, or crack from expansion during freeze thaw cycles.  Another advantage of concrete pavers is their strength.  Poured concrete is rated at about 3,000 psi, whereas concrete pavers carry a rating of at least 7,000 psi.  If it does not carry a rating of at least 7,000 psi, it is not technically considered a paver.  More reputable manufacturers, such as Techo-Bloc, Unilock, and Belgard, having ratings of over 10,000 psi.  They also carry a full lifetime warranty that covers the structural integrity of the paver.

Concrete pavers are more durable than asphalt, offering higher resistance to abrasion, freeze thaw cycles, de-icing salts, concentrated loads, and stains.

Poured concrete is considered a rigid pavement that works on the principle of the layer of concrete protecting the soil subgrade.  Loads are spread by the concrete and bridge soft spots in the soil.  Poured concrete is durable, but requires time to cure, whereas pavers are ready for use immediately upon installation.  Poured concrete cracks and deteriorates due to shrinkage, loads,  and weather.  In contrast, the joints in an interlocking pavement contribute to it’s strength.

People often wonder what keeps the pavers from moving after they have been laid. There are 3 types of interlock that keep them in place.

Vertical Interlock is achieved by the shear transfer of loads to surrounding pavers through the sand in the joints.

Rotational Interlock is maintained by the pavers being of sufficient thickness, placed closely together, and restrained by a curb or edge restraint from lateral forces.

Horizontal Interlock is achieved through the use of laying patterns that disperse forces.  Certain shapes have been shown to contribute to horizontal interlock, offering additional resistance to lateral forces.  Stable edge restraints also maintain horizontal interlock, keeping the pavers tight at the edges of the pavement.

If not properly installed, all of these aspects can fail over time.  The result would be heaving, settling, rotating, or separation around the perimeter.  A properly installed paver project would require minimal attention over the lifetime of the pavement.