In Colorado, for example, nearly 45 million tons of aggregate, or about 12 tons per person, were produced during 1994. Aggregate Quality Aggregate quality is determined by its physical and chemical properties, and is a combination of these two parameters. The quality of the aggregate required for a specific use related directly to that use. For example, to be used in portland cement concrete, aggregate should be both physically satisfactory, and chemically innocuous. For this map, potential sources of aggregate are defined according to general physical and chemical quality.
Physical quality is defined as satisfactory, fair, or poor.
Satisfactory aggregate has physical properties that make it suitable for most purposes. Fair aggregate has physical properties that make it useful for many purposes, but it commonly can not be used where engineering specifications are strict such as in concrete or asphalt. Poor aggregate has physical properties that greatly limit its use. In many circumstances, potential sources of crushed stone can be processed to improve its quality to meet special requirements. Chemical quality is defined as either innocuous or deleterious.