Aggregate is a granular material, such as sand, gravel, crushed stone, crushed hydraulic-cement concrete, or iron blast-furnace slag, used with a hydraulic cementing medium to produce either concrete or mortar. Types of aggregates include Coarse aggregate and fine aggregate. The aggregate of each type is further sub-divided into many types and classification based on its size. The technique of Sieve Analysis is used for gradation of aggregate for use in concrete and for other applications. Aggregate is called bound material when it is mixed with cement or binding materials and referred to as unbound material when used without cement or binding materials. Types of Aggregates