Changes in the Parameters of the Electromagnetic Response of Model Dielectric Samples with Air Cavity Defects under External Deterministic Acoustic Impact

The paper discusses the possibility of testing the air inclusions saturation in cement-sand samples using the acoustic-electrical transformations phenomenon in heterogeneous dielectric materials. An experiment technique is presented including contact external acoustic excitation and contactless registration of the electromagnetic response to such an impact. Methods of samples deterministic acoustic excitation by a ball impact and the experimental determination of the impact energy are described. The model samples size and composition are described, including air cavities in a polyethylene sheath. The experimental studies geometry is shown, indicating the direction of the samples acoustic excitation and the location of the electromagnetic receiving plates. It is shown that the defect-free samples and with air cavities, have different amplitude and frequency of the electromagnetic signals spectral components. The samples with air cavities have the average weight of the EMS spectrum changes towards lower frequencies. This frequency shift effectively reflects the concentration of air cavities defects in a cement-sand samples and this effect can be used when testing concrete products for the presence of air inclusions, and, accordingly, will allow determining the frost resistance of products.