THE NONDESTRUCTIVE TESTING OF CONCRETE: AN UPDATE

Abstract In the last time a lot of new developments in the field of nondestructive testing (NDT) methods justified to prepare a study on the state of these methods, carried out by the author by order of the German Research Foundation (DFG). The author presents a general classification of these methods in a graphical form [1]. Since the 1960s the author himself has been actively involved in research, teaching, practical applications and expertise in this held, so that final conclusions on the advantages and limitations of all these methods, which are always also influenced by the author's own experience, represent a “balanced“ view on this topic [2]. The assessment of the concrete strength in-situ nondestructively is a very controversial subject. The results obtained by NDT methods in many companies by the author are compared with the destructively obtained ones by these building companies. The good agreement of both categories of results is a further support for the use of NDT and for a quantitative approach of their accuracy. Own developments in the use of simultaneous NDT to predict the compressive strength of concrete are also presented [3]. Due to the strict limitation of the paper's extent, only the determination of concrete compressive strength will be discussed.