The next layer is a geotextile fabric. Geotextile fabrics are permeable which have the ability to filter, reinforce, protect or drain the soil underneath. When used with concrete interlocking pavers, this layer helps to drain water and helps protect against erosion; especially when paving on a hill or slope.
The next layer is a compacted aggregate base. This layer is composed of various sizes of gravel that are compacted to form a sturdy base. Bedding sand is next and is usually laid to a depth of one inch. Edge restraints need to be in place before you can lay the paving stones. Edge restraints are the border that holds the pavers together.
You want the edges of your concrete interlocking pavers held firmly in place so that over time they do not start to separate. Finally you can lay the paving stones, leaving a small gap in between the stones. Compacting the pavers pushes them into the bedding sand and helps to stabilize the stones before the final layer; which is to add joint sand over the entire surface, compact them again with a vibrating plate to fill all the joints and gaps. This procedure creates interlock.
Concrete interlocking pavers allow for a transfer of movement so that heavy loads will not crack or damage the surface. The surface is flexible and moves and adjusts depending on the water level, stress load, and climate. Standard concrete slabs are rigid and do not have any flexibility.
That is why concrete slabs can crack and break over time. Other factors that cause concrete slabs to break are shrinkage, soil expansion, and frost heaving of the sub-grade layer. Fiber reinforcement and rebar can add to the strength of concrete, but even that will not eliminate the inevitability of cracking and breaking.
A concrete interlocking paver system is easy to maintain as well. For the most part you can treat it like any other paved surface. There may be a few instances of surface weeds, but most commercially available weed killers can keep your surface weed free.
Most manufacturers of concrete interlocking pavers will provide a lifetime warranty against cracking and breaking; especially if properly installed. Properly installed concrete interlocking pavers can and will last a lifetime. Improperly installed concrete interlocking pavers can separate, sink, and fail in a matter of years.
To ensure that your paving system has all the beauty and longevity that it deserves choose an installer that is experienced in these types of installations.