Decomposed granite is sometimes used in road construction, although it must be compacted to form a firm driving surface.
Decomposed granite, sometimes referred to as DG, is most commonly recognized as a building and landscaping material. It is popular in path, parking lot, and road construction, as well as backyard landscaping. Decomposed granite consists of weathered granitic particles that range in size from gravel to silt and often include some clay. The name decomposed granite refers to the fact that the particles are the result of natural erosion or decomposition of the granite rock.
One of the most common places to find DG is on hiking trails. The material is reasonably stable when compressed and remains a permeable material, allowing satisfactory drainage. In addition to walkways, decomposed granite is commonly used to build driveways and parking areas. Decomposed granite is also sometimes used in road construction, although it must be compacted to form a firm driving surface.
Decomposed granite is popular in landscaping as a hard surface material. Can be used as a ground cover, mulch, patio foundation, or to create pathways. Decomposed granite is a very green option because it is a natural product, it is permeable and provides a rigid landscape that does not require water. Once the granite is in place, it will continue to resist, adding beneficial nutrients to the surrounding soil and plants. Not surprisingly, decomposed granite is a particularly popular landscape choice in arid regions.
Depending on the climate and intended use, the DG can be worn alone with moderate compression to hold it in place, or it can be attached with stabilizers. If the granite spreads itself, it is usually contained with some type of border or frame to prevent the granite from being easily washed away. Conversely, if decomposed granite is set with stabilizers or resins, the hard cap will be more permanent and stable, but permeability will be reduced, making drainage an important consideration.
Decomposed granite generally refers only to naturally weathered granite; however, it is often spoken of interchangeably with crushed gravel and crushed stone. Each of these products has angular parts and usually a percentage of thin parts. They are often used for similar types of construction or landscaping processes.
The formation of decomposed granite occurs over time and is the natural result of weathering and erosion of granitic rocks. Wind and water physically and chemically affect granite, eventually breaking down the small pieces that form decomposed granite. The final product is mined in granite quarries, often together with other granite products such as large blocks, slabs, and manufactured crushed granite.