Concrete NDT :- Ultrasonioc Pulse Velosity Test The ultrasonic pulse is generated by an electroacoustical transducer. , When the pulse is induced into the concrete from a transducer, it undergoes multiple reflections at the boundaries of the differ& t material phases within the concrete. A complex system of stress waves is developed which includes longitudinal ( compressional ), shear ( transverse ) and surface ( rayleigh ) waves. The receiving transducer detects the onset of the longitudinal waves, which is the fastest. Because the velocity of the pulses is almost independent of the geometry of the material through which they pass and depends only on its elastic properties, pulse velocity method is a convenient technique for investigating structural concrete.