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Asphalt pavement being a continuous flexible road surface has many advantages such as good driving comfort,low noise,high strength,small vibration and convenient maintenance due to which it have been used worldwide.But as a high grade road surface material,it have higher requirements for various road performances.Therefore,timely monitoring and evaluation of asphalt concrete becomes a key task.In order to measure characteristics of asphalt concrete efficiently and scientifically,this study proposes non-destructive ultrasonic testing.Nondestructive test technology(NDT)is a technique for determining and evaluating the usage of materials without damaging the original properties of the material.In this method,ultrasonic waves are excited by ultrasonic transducer,propagated through medium and received by the transducer at the other end.These elastic waves include longitudinal(L)and shear(S)waves.Longitudinal waves are called primary waves because they have highest propagation speed.Based on acoustic information such as wave velocity,amplitude and frequency;relationships between acoustic parameters and physical parameters such as density,void ratio and dynamic modulus of asphalt concretes are developed to verify the purpose of NDT testing.This study is segregated into two parts.In first part,four different types of asphalt concretes AC-13,SMA-13,AC-20 & AM-20 were developed in laboratory,which were used subsequently for density,void ratio,dynamic modulus and ultrasonic wave tests.Relationships of ultrasonic wave velocity with density,void ratio and dynamic modulus are developed,which can be used as practical references to evaluate density and degree of compaction of asphalt pavement by detection method.Further,dynamic moduli of asphalt concretes under high frequency are calculated using wave velocity and compared with measured dynamic moduli at frequency 10 Hz by UTM test machine.From this comparison,correction factors for asphalt concretes are calculated,which can be used to replace low frequency standard dynamic test,which is more expensive and time consuming by multiplying the correction factors with calculated dynamic moduli and provide a practical reference for dynamic moduli of different types of asphalt concrete at low strain.In second part,numerical modeling of ultrasonic wave velocity through asphalt concretes was carried out using explicit finite element method in ABAQUS software.Simulated wave velocity results under calculated dynamic moduli and measured dynamic moduli as input are compared with ultrasonic wave test results to verify the feasibility of nondestructive ultrasonic test for road pavement of low strain.In addition,effects of varying density,dynamic moduli,at different depths and times,attenuation,crack sizes and location on ultrasonic wave propagation are analyzed.