ABSTRACT
Aggregate is defined as processed soil. Natural aggregates are obtained from quarries or riverbeds. The process of obtaining aggregates consists of blasting or dredging. Large-size particles are crushed to obtain usable sizes that range from 50 mm to less than 0.075 mm for most pavement mixes. Since aggregates are derived from parent rocks, their characteristics depend on the properties of the parent rocks. The parent rocks can be classified in terms of their geologic origins, which dictate their chemical composition and hence many of the other key properties that affect their behavior and performance. Artificial aggregates are obtained as by-products of other industrial processes (such as slag from the production of steel).
