Aggregate Abrasion Value (AAV):
The resistance of aggregate to wear is known as hardness of aggregate. This property is particularly more important for the concrete used for wearing surfaces like, road, runway, etc. It is measured in terms of aggregate abrasion value and determined by Deval Abrasion Test Machine or Los Angeles Abrasion Test Machine. The latter is more commonly used as it gives better representation of hardness. The test method combines the attrition and abrasion affects both. The test sample of clean aggregate is taken in standard manner as specified in IS 2386 (Part IV): 1963 and dried in oven at 105-110oC. It is placed in Los Angeles Abrasion Test Machine along with the specified abrasive charge. The abrasive charge is in the form of cast iron spheres or steel spheres. Each sphere is of approximately 48 mm in diameter and of 390-445 gm in weight. The aggregates together with the abrasive charge are rotated in the machine @ 20-33 revolutions per minute for 500-1000 revolutions (depending upon the grading of the aggregates). After completing the specified revolutions the aggregate is taken out and sieved through 1.7 mm sieve. A weight of the aggregate and coarser than 1.7 mm is taken after washing and drying in standard manner, which is known as final weight.
AAV = (Original weight - Final weight)/ Original weight × 100
A limiting value of abrasion-value for concrete aggregate is 16%.