Interlocking paving stones have been used since Roman times.  In the Ancient World, pavers were made of actual stone, and they were used to build roads that are still usable today.  After the Industrial Revolution, the use of concrete became widespread throughout the developing world.  Builders and landscapers began to manufacture pavers during the mid 1940s.

Since that time, the American paver market has skyrocketed.  Between 1999 and 2004, it more than doubled.  Seventy seven percent of that increase was in the residential landscaping market.  American homeowners who have grown tired of paying for expensive, cracked concrete repair are now seeing the value in a decorative form of concrete that can imitate any material and that does not crack.

The type of concrete used to makepaver driveways, paver patios, and paver walkways features “zero slump.” Without getting too technical in our article, suffice to say that “slump” refers to the amount of water used to mix concrete.  When gravel, sand, cement, and color are mixed with a minimal amount of water, it can be molded into any shape and cut into interlocking paving stones that create a strong, flexible surface where each individual stone is immobilized by surrounding stones.

The most common misconception about the relationship between pavers is that their edges fit together and grip like pieces in a puzzle.  This is not how they function.   Instead, the individual pieces of concrete are collectively held together in such a way that they work together as a flexible unity.  The key ingredient to creating this unity is a special kind of sand called joint sand.  Unlike silica sand, which has rounded edges, joint sand has rough, angular, jagged edges. 

When it fills the joints between interlocking paving stones, the individual sand particles grind against each other and freeze into a single mass.  In the process, the concrete pavers are locked into position and can no longer move individually.  This makes the surface as strong as the collective mass of the concrete, but flexible enough to withstand the constant shifting of Houston’s clay like soil which is notorious for splitting concrete driveways, streets, sidewalks, and parking lots.

Houston landscaping professionals at Exterior Worlds follow a systematic, proprietary technique that involves digging several inches into the ground to prepare a special foundation of crushed stones and gravel over which to lay the stand and the concrete pieces.  Interlocking paving stones require this foundation of packed gravel and crushed stone foundation to achieve the proper balance between strength and flexibility. 

If the hardscape is intended to be permeable, this process becomes even more complex, because the foundation must be thick enough to slow pollutants down without blocking the filtration of water completely.  Once the foundation is complete, joint sand is then added.  When the pavers are laid down and pressed tightly pressed down into the sand, it rises up to fill the spaces between the concrete edges.  This seals the joints between the concrete pavers, resulting in a contiguous, flexible surface.

As complex as the installation of interlocking paving stones may be, maintenance is simple and very infrequent.  If there ever is a problem with an individual paver, it can be repaired by repairing the foundation layer beneath it and replacing it at minimal labor costs.