Review of NDT methods in the assessment of concrete and masonry structures

This paper reviews the state of non-destructive testing (NDT) methods as ap plied to the civil engineering industry in the Millennium Year, 2000. The b asic principles of NDT methods are described with particular reference to t he five major factors that influence the success of a survey: depth of pene tration, vertical and lateral resolution, contrast in physical properties, signal to noise ratio and existing information about the structure. The mai n NDT methods used in engineering investigations are discussed and illustra ted with brief case histories from the literature. The integration of NDT s urveys into the investigation of structures is described. The underlying re asons why NDT methods are perceived as 'not working' by the structural engi neer are identified as: a lack of understanding of variability of both the construction materials used and NDT methods themselves. (C) 2001 Published by Elsevier Science Ltd.