siyab houshmandi khanghahi
Ahmet TORTUM
seyed javid zakavi
Abstract
Since aggregates constitute a major part of the volume and mass of an asphalt mixture, they obviously have considerable effect on its performance. In fact, nominal maximum aggregate size (NMAS) and consequently the air-void content of an asphalt mixture play a very important role in its performance, particularly in terms of indirect tensile strength and modulus of elastisity. Three materials with 9.5, 12.5 and 19 mm NMAS were used in this research. Specimens were prepared by Marshall asphalt mix design method with 4, 7 and 10% air-void content, and indirect tensile strength and ultrasonic tests were performed on them. Based on the results of indirect tensile strength test, parameters including yield horizontal strain, total fracture energy, fracture energy to failure, horizontal tensile stress, and vertical compressive stress, and of ultrasonic test, parameters including acoustic wave velocity and modulus of elastisity were investigated. The results of indirect tensile strength test show that the asphalt mixture with 4% air-void content outperforms other specimens. Moreover, increasing the air-void content reduces the values of all parameters of indirect tensile strength and ultrasonic tests. Increasing the NMAS diameter increases the acoustic wave velocity and modulus of elastisity.
Keywords
Asphalt, Air-void, Aggregate, Ultrasonic, Indirect tensile strength
