Problems of acoustic testing of large-size concrete building structures: Fid-Bau Portal

Problems of acoustic testing of large-size concrete building structures

Kachanov, V.K. / Sokolov, I.V. / Avramenko, S.L.

New methods and devices for acoustic testing of large-size (>1.5 m) concrete building structures (foundations, walls of buildings, airfield pavements, bridge pillars, slabs, blocks, beams, etc.) based on the use of methods of free and forced vibrations are reviewed. The impact-echo (IE) method (in some cases, the resonance method) is a quite widespread technique for acoustic testing of concrete BCs (abroad) and is virtually the only acoustic method enabling testing of extended articles thicker than 1.5 m in the case of one-way access. Unfortunately, the IE (or resonance) method is not developing in Russia for testing large-size concrete articles; there are virtually no publications on the results of domestic researchers. There is only scanty information on the use of foreign equipment and no appropriate standards determining the position of this method among other NDT methods. No appropriate equipment for the IE method as applied to testing of BCs is manufactured in Russia. The IE method has certain limitations: the testing techniques and devices existing abroad allow inspection by the IE method of virtually any thickness but only for extended articles (foundations, walls, floors, and piles) whose lengths and widths exceed their thicknesses by a factor of >5. The existing testing techniques are unsuitable for testing compact articles (for which at least one dimension differs from the thickness by a factor of <5, a feature typical of supports, columns, blocks, etc.). To solve the formulated problem, research has been performed at the Moscow Power Engineering Institute in order to develop techniques for testing compact concrete articles and measuring the velocity of sound in large-size compact concrete BCs with shapes unknown beforehand, as well as to develop flexible multifunctional equipment supporting various techniques (the resonance and IE methods and any variations of these methods) for solving problems of testing of extended compact concrete BCs. The results of these studies will be considered in subsequent publications.