Prepared by CSBE Team, 2005
A most effective manner for achieving beautiful, water-conserving gardens is through combining planted (softscaped) and paved (hardscaped) areas. There are numerous solutions for this incorporation of paved areas - which can include materials such as ceramics, stone, or concrete - within a garden context. One can create planted areas that surround paved surfaces and that include a mixture of both low plants and trees. This composition affords a sense of lush greenery and also provides shade from the hot sun. Another option is to place small green areas within paved surfaces to create an attractive composition of colors and textures resulting from the combination of the plants and the paved surfaces of the garden.
In addition to providing an aesthetic feature that saves water, paved surfaces serve as an efficient water harvesting system. They harness water that can be directed either into a collection tank or to planted areas where the soil would store it for later use. Also, paved areas can serve various utilitarian and recreational purposes that include sitting, playing, or even parking vehicles.
It is important when creating a paved area in a garden to choose paving materials that are appropriate for outdoor use. Select materials that resist glare and slippage, and that do not show the accumulation of dust or dirt easily.
Also use materials that tolerate the various elements since outdoor areas are regularly subjected to potentially destructive forces including climatic changes and heavy uses. Generally, it is preferable to use locally available and tested paving materials. These usually are less expensive, and extra supplies can be found relatively easily when the need arises for maintenance or expansion work. Also, the availability of an experienced work force usually is more readily available for local materials.
Other issues that need to be considered include the composition of the bedding that supports the paving surface. Ideally, the bedding should be placed on top of an undisturbed layer of soil. If such a layer is not available, the soil would require compacting. A compacted layer of aggregate then would be placed on top of the soil. A layer of concrete might be needed over the aggregate, and this concrete layer might require reinforcement. The exact composition of the bedding depends on factors such as the type of soil originally located on the site and the type of use intended for the paved area. Obviously, an area intended for parking will need to be sturdier than one used primarily for seating.
A wide variety of paving materials can be used within a garden context. These include the following:
Pre-cast concrete tiles
Concrete provides a diversity of possibilities as a paving surface. Concrete tiles can be found in various thicknesses that offer different strengths, they come in a variety of shapes and colors, and can be made to resemble other materials such as stone or brick (figure 1). Concrete tile types include those with relatively smooth surfaces, as well as ones with slightly protruding patterns. Another common type of concrete paving tiles is exposed aggregate tiles, which consist of concrete mixed with pebbles, thus providing a somewhat rough texture (figure 2).
Other possibilities include interlocking concrete paving systems, which provide a number of advantages in relation to rectangular or square concrete tiles (figure 3). The interlocking nature of such systems strongly binds individual paving units and prevents any lateral movement in them. Consequently, they do not require mortar to bond the individual paving units to each other. Because mortar is not used, these systems effectively deal with water ponding problems since excess water simply seeps through the joints to settle in the soil below. Also, the strong bonding created between the individual paving units means that these systems do not require a concrete bedding and can be placed directly on a compacted layer of sand. Another advantage of interlocking paving tiles is that they can be removed easily and placed again in the same location (if maintenance work is to be carried out) or used in a different area.
Cast-in-place concrete can be used to provide various patterns and textures (figure 4). This method relieves one of having to transport finished concrete tiles to the site. However, when using such a system, make sure to place contraction joints at adequate intervals to avoid cracking.
Cast-in-place concrete includes stamped concrete, which allows for creating a wide variety of paving patterns and textures through the use of rubber molds that are applied to the concrete paving before it dries (figure 5).