Use of ultrasonic tomography for the assessment of critical aspects of doweled joints in concrete pavements

The critical (design) parameters to be controlled for concrete pavements construction, in addition to the concrete strength, are slab`s thicknesses and doweled bars position at contraction joints, as they affect hugely structural performance, and, if not properly built may cause early ruptures. Construction compliance of such parameters is nowadays assessed through nondestructive techniques (NDT), such as ultrasonic low-frequency waves. Alignments of inserted doweled bars at contraction joints are analyzed herein for actual slabs as well as how thickness affects such position. Tests were carried out over an airport hangar apron after it has been built. Twenty-five concrete slabs were assessed using ultrasonic tomography allowing to verify disconformities of thicknesses and bars vertical and horizontal misalignments, with fair accuracy on measuring deviation angles of bars.