An instrument for monitoring the quality and thickness of slabs has be
en designed The quality is assessed by estimating the slab's Young's a
nd shear moduli from ultrasonic surface wave and ultrasonic body wave
velocities. The thickness is determined from results obtained with the
impact echo and above tests. In this paper the conceptual and actual
designs of the device are described, the advantages of; and problems w
ith the approaches reported the theoretical limitations of the methodo
logies expanded, and the results from several field-testing programs d
iscussed. Based on test results the device is quite promising and its
capabilities are more diverse than those of existing devices.