Abstract
Current research and development of non-linear ultrasonic spectroscopy methods shows these methods to be very promising for material testing and defectoscopy in the near future. Our experiments focused on the testing of lightweight concrete specimens using the single-frequency excitation method. We studied the concrete specimens' structure after having been stressed by a mechanical force. Measurements were realized before and after mechanical loading.
Highlights
According to the relevant standards, there are three kinds of concrete: lightweight, plain and heavyweight concrete
The volume mass of lightweight concrete is less than 2000 kg/m3
Depending on the intended application, the lightweight concrete group consists of three subgroups: thermal insulating lightweight concretes, their intended application falling into the thermal insulation field, structural insulating lightweight concretes, their function being both supporting and insulating, and, last but not least, structural lightweight concretes, whose main function is their bearing capacity and the main requirement is strength combined with low volume mass. (Kucharczykova & Kersner, 2008; Korenska et al 2005, Plskova et al 2009)
Summary
According to the relevant standards, there are three kinds of concrete: lightweight, plain and heavyweight concrete. On the basis of non-linear effect studies, new NDT methods have been designed (Van den Abeele et al 2000, Zaitsev et al 2006). These methods are based on the elastic wave non-linear spectroscopy. Existing linear acoustic methods focus on the energy of waves reflected at structural defects, analyzing the reflected wave energy, wave velocity or amplitude variations None of these "linear" wave characteristics is as sensitive to small cracks as the specimen non-linear response (Nagy, 1998; Van den Abeele et al 2001; Van den Abeele et al 2009). It is predicted that these advanced techniques can contribute a great deal to the improvement and refinement of the NDT methods in the building industry practice
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