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Abstract- Non-destructive methods are nowadays widely used to evaluate the performance of structures and infrastructures, including pavements. In this paper, Ultrasonic Pulse Velocity (UPV) test is investigated for evaluation of the behavior of Hot Mix Asphalt (HMA) mixtures. The effect of different mixtures parameters, including gradation, bitumen and filler contents are studied by means of indirect computation of Elastic modulus of HMA from UPV test and its comparison with experimentally derived Stiffness modulus values from Indirect Stiffness Modulus (ITSM) test.
Keywords- UPV test, HMA, stiffness modulus, Young's modulus
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1. INTRODUCTION
Many factors affect the mechanical properties of HMA mixtures, such as the percent of fractured particles (F.P %), bitumen content, temperature, gradation and filler content [1, 2]. Based on the literature, it would be useful to study the relation between Stiffness Modulus (SM) and UPV test parameters. For this purpose, the first step is to investigate the effect of different mix parameters and the accuracy of results presented by UPV. The purpose of Non-Destructive Test (NDT) methods is to obtain information on a given structure without causing any destruction or damage to the investigated area. Various NDT methods have been developed and applied in engineering with varying degrees of success [3-5]. Current wavebased NDT methods, such as UPV, impact echo, and spectral analysis of surface waves (SASW), have been used for the evaluation of material properties. In this study, the variation of UPV test results of HMA mixtures with regard to changing the gradation, filler and bitumen contents of mixtures were investigated. Assessment of the UPV test results were done by means of a comparison of the indirectly derived Young's modulus of the HMA specimens from the UPV test and their stiffness modulus from ITSM test.
2. EXPERIMENTAL PROCEDURES
The binder was selected to be 60-70 penetration degree asphalt binder, produced by Isfahan Refinery, Iran. The penetration test was carried out since it is the standard used in Iran, although many countries are moving toward performance grade designation. The properties of used bitumen were tested and were all within the limits defined for 60-70 asphalt cement by the standards [6]. Two types of gradations were used and shown in Table 1, which is in accordance with Iranian standards for...