There are two main classes of aggregates: natural and manufactured.
Natural aggregates come from sand and gravel deposits. These formations often contain materials like clays and silts that must be thoroughly processed out before using the sand and gravel in commercial applications. Manufactured aggregates are obtained from deposits of sedimentary rock or igneous rock. These types of aggregates need to be blasted, ripped or excavated and processed down to fit commercial specifications. Deleterious material needs to be removed from both classes of aggregates. Processing these materials typically requires various steps including reduction and sizing and also may include dewatering and sorting. Producers can use a variety of crushing, screening, dewatering and conveying equipment to meet their desired specifications.