Almost any type of stone available can be used in the creation of aggregate. Most aggregates consist of sand, gravel and crushed stone. The crushed stone component of aggregates accounts for approximately 85 percent of its weight. Gravel and sand designed for construction applications make up the last 15 percent of the aggregate. Aggregate is a low-cost product per ton, but is very heavy, which can greatly increase transportation costs.
Aggregates are also often used to form the foundation of asphalt as well as concrete pavement. It can take approximately 25,000 tons of aggregate to supply the proper foundation for a single mile of two-lane asphalt road. Proper asphalt driveway construction calls for a crushed stone foundation that reaches several inches below the surface. Having the proper foundation beneath asphalt and concrete pavement helps prevent cracking, crumbling, bending, sinking and a host of other issues linked with asphalt and concrete pavement.
A layer of crushed stone is usually installed below a home or building's foundation. These crushed stone layers help provide stability for a foundation. Aggregate provides the perfect base for concrete, a widely used material for building foundations. Aggregate is also used in erosion control projects. Erosion control stone's function is exactly as its name implies, it merely acts to curb the effects of erosion on an object. Railway ballasts are widely constructed out of aggregate.
North Carolina is one of America's largest crushed stone producers. In 2000, North Carolina's crushed stone production reached approximately 70,000,000 metric tons at a value of just under half a billion dollars. Approximately 135 crushed stone quarries as well as 500 gravel and sand production locations make up North Carolina's network of aggregate production facilities. Sand, gravel and crushed stone plants account for roughly 85 percent of North Carolina's permitted mining operations. Aggregate mining operations are taking place within 80 of the state's 100 counties. Most of the aggregate flowing around North Carolina is transported via dump truck. In certain cases, railroads and barges are employed to transport aggregate.