ABSTRACT
Aggregate can be defined as natural or processed sand, gravel or crushed stone or any combinations thereof. Natural aggregates are procured from pits or riverbeds whereas manufactured aggregates are obtained from quarries. 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. Petrographic examination of aggregates can be conducted to identify different parent rock materials and minerals in an aggregate sample. Such examination can provide valuable information regarding the suitability of aggregates for asphalt and concrete mixtures, particularly with respect to their durability, such as resistance against breakdown under freeze–thaw or moisture actions. For both asphalt and concrete mixes, the resistance against degradation by abrasion, or toughness, can be measured by the Los Angeles (LA) abrasion test.
