Pavers either are cut from stone or cast in molds using man-made materials. Generally, aggregate pavers are decorative precast concrete pavers made of cement, aggregate, and water. In most concrete, the aggregate material used consists of sand and small pebbles and is not obvious. The aggregate in aggregate pavers is a larger and more decorative material and is exposed. Frequently, the aggregate material consists of stone or pebbles, but it may also include recycled materials.
There are two methods of creating the aggregate pavers. The first is to cast the paver, and before the cement is fully set, the worker washes away the top layer, called the skin, of cement to expose the aggregate. The second method works best for a large aggregate, like river rocks, or for limited supplies of the aggregate, such as decorative glass. In this method, the manufacturer pours the concrete pavers without the aggregate and then places the aggregate material onto the surface and presses it into the concrete. Usually workers use a tamper or a vibrating machine to set the aggregate into place.
Most people choose aggregate pavers by the look of the aggregate. Colorful rocks are among the most popular selections, but other choices are gaining popularity. With the push for green building and recycling, several companies offer alternative aggregate, such as porcelain scraps from a lavatory fixtures manufacturer and glass blobs made of recycled glass. Often paver fabricators color the cement mix in order to enhance the beauty of the aggregate. An example of this is dark-tinted cement accented with the white porcelain chips.
Besides providing a market for recyclables, aggregate pavers provide other benefits, both economically and environmentally. Solid-pour patios, driveways, and other large areas frequently crack from the pressure of temperature extremes or weight loads. Pavers solve this problem by being able to expand and contract individually. It is more cost effective to replace a few cracked pavers or repair the substructure. Large surfaces of solid-pour concrete or asphalt cause water runoff, which is an environmental problem, but the small spaces between pavers allow water to seep into the ground and eliminate water runoff.
Generally, pavers are low maintenance. Aggregate pavers last longer and stay attractive if they are sealed. This prevents water and chemicals from eating away the concrete that holds the aggregate in place. This erosion is common in all concrete surfaces, but it is most harmful in exposed aggregate applications. Dealers sell the sealer in various finishes, from matte to high gloss, so the consumer has a wide range of choices.
Despite the name pavers, not all aggregate applications are used as pavers. Often builders use exposed aggregate slabs as building facades or indoors as flooring or wall coverings. At the Mid-America Mall Memphis in Tennessee, crushed red granite aggregate paving tiles make a very attractive walkway. As the size of granite aggregate is often 0.25 to 0.625 inches (about 0.6 to 1.6 cm), it is more economical than solid granite pavers are. Sometimes landscapers or homeowners use aggregate panels to enhance garden walls.
Precast aggregate pavers come in many shapes and sizes. Some of the most popular square or circle sizes are 12 inches, 18 inches, and 24 inches (approximately 30 cm, 46 cm, and 61 cm). The traditional smaller paver size is 4 by 8 inches (10 by 20 cm), but other sizes and shapes usually are readily available at garden and building centers. Many of the pavers are created in interlocking shapes for creating interesting designs. Gardeners typically find that the rocky appearance harmonizes with the natural beauty of their gardens.