The spectral analysis of surface waves (sasw) test can be used rapidly in the field to determine the stiffness and thickness of the pavement surface layer. The test is equally applicable to asphalt concrete and portland cement concrete pavements. One of the most important features is that testing can be performed quickly (in approximately 5 min at each location). Values of young's modulus andthickness of the surface layer are determined using a straightforward procedure. Analytical studies are presented to substantiate this procedure and to optimize its use. Several case studies from asphalt concrete pavements and one portlandcement concrete pavement are presented. The results show that this adaptation of the sasw test provides values of young's modulus that are sensitive to the elastic stiffness of the surface layer and also provides reasonable estimates of the thickness of the surface layer. In addition, changes in the stiffness of the surface layer with time and temperature are easily monitored in situ. This paper appears in transportation research record no. 1260, Measurement of pavement surface condition 1990.
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