MODULI OF PAVEMENT SYSTEMS FROM SPECTRAL ANALYSIS OF SURFACE WAVES

A nondestructive technique for pavement evaluation is necessary to determine moduli of the various materials in existing pavement systems. Dynamic field testing can be used to calculate moduli from velocities of surface waves propagating through the different layers of the pavement system. A new, efficient technique incorporating an impulsive source has been developed to replace the slower, steady-state vibration technique. Frequency and phase content of the surface waves generated by the source are collected with portable spectral-analysis instrumentation. Results for field tests conducted at two flexible pavement sections yielded wave velocities measured by the spectral-analysis technique that were within 10 percent of velocities determined from crosshole tests performed at both sites. This comparison confirms that an accurate profile of velocity versus depth (hence modulus versus depth) can be obtained by using this rapid, nondestructive spectral-analysis technique. (Author)