Paver (flooring)

Concrete paver blocks in a circular pattern

Concrete paver blocks in a rectangular pattern

Brick paving being laid on a sand base, in south west England

An interlocking concrete paver is a pre-cast piece of concrete or brick commonly used in exterior hardscaping applications. Pavers were developed in Europe and introduced into the United States in the early 1970s.

Interlocking paving stones are installed over a compacted stone sub-base and a leveling bed of sand. Concrete paving stones can be used for walkways, patios, pool decks and driveways and airport or loading docks.

Instead of connecting the pavers by pouring grout between the joints as one would with tiles, sand particles are spread over the pavers and tamped down. The sand stabilizes the interlocking pavers, yet allows for some flexibility. This type of pavement will absorb stress such as small earthquakes, freezes and thaws, and slight ground erosion by shifting each tile slightly. Therefore, they will not crack or buckle like concrete, though bad weather may make potholes.

The special tools needed for installing interlocking pavers are vibrating compaction machine or "Vibra Plate" and Shear Cutter. The former is used to compact the base material to 90% density minimum and also to set and interlock the pavers into the sand bed. The latter is used to cut the pieces to fit at corners and edges. The sand does not easily wash out with rain or garden hose water and a sealant can be spread on to further lock the sand.

Standard thicknesses are 60mm (for light traffic) and 80mm (heavy traffic). 50mm too is common in some countries like Pakistan (used for footpaths etc).

Benefits of paver over asphalt and poured concrete include high compressive strengths (7000+psi as per BS and 8000+psi as per ASTM codes), pleasant look, time saving, easy removal and relaying.

History

Paving has been around for almost 5,000 years. The oldest paved road was discovered in the summer of 1994, in Giza, Egypt.^[1] This road is the oldest paved road in the planet built over 4,600 years as a route to connect an ancient basalt quarry to Lake Moeris and used to transport large stones for the construction of the temples of Giza. This ancient road measures 7 ½ miles (12 km) in length and 6 ½ feet (2 m) in width. The road was paved with thousands of slabs of sandstone and limestone and some logs of petrified wood. The still standing road was used to carry massive stones using sleds and proved to be reliable. ^[2]

In 500 B.C., during the Roman Republic, Rome introduced the segmental pavers in their road system. The Romans needed their armies to travel quickly within the empire and the current kinds of roads posed many problems. The roads were often muddy, created too much drag, and also created lots of dust in heavily transited areas. To solve that problem the Romans created roads with deep roadbeds of crushed stone and a top layer that included six sided capstones. The Roman roads provided the troops with much faster transportation and proved to be reliable as they still stand to this day.

Over time many roads where built and paved based on the Roman road design and natural stones and clay were used to pave the roads up until the 18th century. At that point, British builders realized the importance of selecting clean stones for surfacing to make better roads. The selection of clean stones made road paving a bit costly until later on when concrete pavers could be manufactured. Most of these roads provided a means of fast transportation with the use of horse drawn carriages.

In the 1940’s Holland faced a problem with its roads because Holland is situated below sea level, therefore the ground constantly shifts, moves and sinks. Poured concrete was not an option because it is not flexible and would strain and crack. Therefore, Holland turned to the use of individual stones placed in sand, which provided a flexible yet durable road that would not be affected by shifts and movements of the ground.

After World War II, most of Europe was in ruin and reconstruction began. The roads where rebuilt using paving stones as they have historically proved to be able to withstand certain demands that concrete and asphalt could not meet. German engineer, Fritz Von Langsdorff developed a choice of shapes and introduced the use of colors in concrete pavers. Historically pavers where often made of natural stone or clay, but the introduction of concrete paving stones turned out to be more economical to produce and had tremendous pressure resistance. The first concrete paving stones where installed in Stuttgart, Germany.

Concrete interlocking pavers where now an efficient and economical choice as mass production started in the 1960’s in Germany. In the 1970’s production technology spread through Europe and other parts of the world including the United States. Since then America has seen a significant growth of concrete interlocking pavers and has been growing steadily.

Manufacturing

Interlocking pavers are manufactured by machinery in factories. They consist of both fine and coarsely grained aggregate, along with cement compounds. The ingredients are put through pressure and vibration courses, which produce a strong, durable concrete that can then be molded into various shapes and designs. ^[3]

Manufacturing of pavers is done on two types of machines in general. The first being more popular, more productive, cost effective, yielding high strength product is through Block Making Machines. The movements are controlled through hydraulics and the compaction is done through eccentric weight vibrators. The other choice is of Hydraulic press machines that deny each of the above mentioned advantages still common in few countries because of their low capital demand. There is no vibration to move the material in the mold thus voids may remain present. World leader for the former from Germany are Masa and Hess. Americans machines like Columbia and Besser are strong competitors. Some Chinese companies are in the market but they mostly follow or copy the design of these leaders.

External links

• Interlocking Concrete Pavement Institute
• National Precast Concrete Association
• Examples of Modern Residential Interlocking Paving

References

1. ^ WILFORD, JOHN (05 June 1994). "World's Oldest Paved Road Found in Egypt". New York Times. http://www.nytimes.com/1994/05/08/world/world-s-oldest-paved-road-found-in-egypt.html. Retrieved 27 July 2011. 
2. ^ [1], History of Pavers
3. ^ [2], paver manufacturing