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Aggregate is the most fundamental and widely used component of construction. it is used as an unbound material which constitutes about 100% of the volume of base courses, 95 to 93% of the volume of asphalt and about 85 to 75% of the volume of Portland cement concrete. Aggregate is exposed to a number of physical and chemically degrading forces during processing, transporting, and construction. As the main load carrying component of unbound and bituminous and Portland cement concretes, the aggregate must be clean, hard, sound, durable, resistant to abrasion, uniform in quality and free of any detrimental quantities of soft, friable, thin, elongated or laminated pieces, disintegrated material, alkali or other deleterious substance. For assesing the abrasion resistance of aggregates, the most common method is the Los Angeles abrasion and impact test (LAAI) which determines the relative competence or resistance to abrasion of the aggregates. |
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