Dielectric Properties of Concrete Specimens after Heat Stress

Abstract

Concrete quality depends on various stress factors. The impedance spectroscopy method, as one of the non-destructive testing method group, was used to characterize concrete specimens and track the changes in the concrete spectrum after heat stress. The temperature range was between 0°C and 1200°C. Variances in the tan δ (f) and Im Z(f) or Re Z(f) of the specimens under investigation have been observed. The specimen quality has been described by means of the loss type prevailing in the material. The results of this study are expected to provide information about the correlation between the relative permittivity and changes in the structure for heat stress samples.

Impedance spectroscopy – comparison of dielectric model with experimental results

“…In theory, three types of model are distinguished [10]. Model 1, according to Cole's expression (related to Debye's equations for complex relative permittivity):…”

“…For the measurements, three sets of five specimens were created; these differed from each other in the forming compression force A frequency range of 40 Hz to 1 MHz was used to analyze the electrical properties of the prepared samples. The measurements were performed using an Agilent 33220A sine wave generator with an output voltage of 5.5 V and an Agilent 54645A dual channel memory oscilloscope, which were wired according to the schematic diagram [9,10].…”

“…For homogeneous materials, the theory of dielectric polarization was built by Debye [6][7][8][9][10]. However, experiments and conclusions on real substances showed differences from the basic theories.…”

Behaviour of cement composites with lightweight and heavyweight aggregates at high temperatures

“…The design of the composition of concrete was based on the experience with the problem of fire-resistant cement based composite materials, and on the results of literary search of technical literature [3], [4], [5], [6], [7], [8] …”

Impedance spectroscopy – comparison of dielectric models with a real RC circuit

“…Employing the apparatus for measurement by impedance spectroscopy methodology (IS) and using a block diagram [1][2][3][4][5], the RC circuit was automatically characterized using the IS alfa application which was programmed for these purposes [6][7].…”