The paper presents the statical research tests of rod bolt made of plastic with a length of 5.5 m, which were performed in a modern laboratory test facility at the Department of Underground Mining of the University of Science and Technology. Innovative The Self-excited Acoustic System (SAS) used to measure stress changes in the bolt support was characterized. The system can be used for the non-destructive evaluation of the strain of the bolt around the excavations as well as in tunnels. The aim of the study was to compare the re-sults recorded by two different measuring systems, thanks to which it will be possible to assess the load of long bolt support by means of the non-destructive method. The speed and simplicity of measurement, access to the sensors, accuracy of measurement and reading should be kept in mind in determining the load of rock bolt support . In addition, the possibility of damage to the sensor as a re-sult of technological or natural hazards should also be taken into account. In economic conditions, the „technical - balance laws of production”, which ex-cludes the use of load sensors on each bolt must be preserved. The use of indi-vidual load sensors of rock bolt support for the boundary state, allows appro-priate protection actions of the mining crew against sudden loss of excavation stability to be taken. The paper presents two basic effects used in the ultrasonic measurement sys-tem. The first result was the existence of stable limit cycle oscillations for posi-tive feedback. This effect is called the self-excited effect. The second effect is called the elasto-acoustic effect. It means that with the change of elastic stress-es in the material bring the change of the speed of propagation of the wave. In this connection, the propagation time between measuring heads is also changed. This effect manifests itself in the change in the oscillation frequency of the self-excited system. For this reason, by measuring the frequency of self-excited oscillation, it is possible to indirectly determine the level of effort of the tested material.

The paper presents a 3D model and simulations of corroding reinforcement bars in a concrete element. Electric potential distributions are calculated in the concrete matrix and on its surface for two rebars arrangements with one or three active (anodic) sites to assess the reliability and identify possible problems when standard test measurements for corrosion assessment in concrete structures are used and conclusion on the corrosion state is inferred. The values of the potential strongly depend on a concrete layer thickness and beyond the threshold of 5-7 cm it is hardly possible to detect the number of active sites on the rebar. Also conductivity – which is not constant in real world constructions – is an important factor. Thus without estimation of the state of concrete it is difficult to draw reliable conclusions on the corroding activity from shear potential measurements on the surface.

In the framework of non-destructive evaluation (NDE), an accurate and precise characterization of defects is fundamental. This paper proposes a novel method for characterization of partial detachment of thermal barrier coatings from metallic surfaces, using the long pulsed thermography (LPT). There exist many applications, in which the LPT technique provides clear and intelligible thermograms. The introduced method comprises a series of post-processing operations of the thermal images. The purpose is to improve the linear fit of the cooling stage of the surface under investigation in the logarithmic scale. To this end, additional fit parameters are introduced. Such parameters, defined as damage classifiers, are represented as image maps, allowing for a straightforward localization of the defects. The defect size information provided by each classifier is, then, obtained by means of an automatic segmentation of the images. The main advantages of the proposed technique are the automaticity (due to the image segmentation procedures) and relatively limited uncertainties in the estimation of the defect size.

Pot-cored coils are commonly used as probes in eddy current testing. In this paper, an analytical model of such a coil placed over a three-layer plate with a hole has been presented. The proposed solution enables the modelling of both magnetic and non-magnetic conductive plates that contain different types of hole, i.e. a through, a surface, an inner or a subsurface hole. The problem was solved by using the truncated region eigenfunction expansion (TREE) method. The analysis was carried out in a cylindrical coordinate system in which the solution domain was radially limited. With the employment of the filamentary coil, the expressions for the magnetic vector potential, and subsequently for the impedance of the cylindrical coil were obtained. The final formulas were presented in a closed form and then implemented in Matlab. The resistance and reactance values were compared with the results obtained in the experiment and using the finite element method in the Comsol Multiphysics package. In each of the cases, good agreement was obtained.

Construction and demolition (C&D) waste management should be accordance with the waste management hierarchy. In practice, C&D waste are often downcycling. It is the result of many factors, including lack of awareness about the value inherent in waste. The paper presents analysis of the adaptability of non-destructive testing (NDT) methods for technical assessment of waste properties. As part of the work, non-destructive testing methods were described and classified in accordance with material and the features they enable testing. The publication presents examples of the use of NDT in the recovery of building materials during construction projects, in the field of influence of technical information of waste on the way it is managed. Finally, a scheme of waste management process during the renovation of an object with the application of NDT methods was presented.

The article presents the results of non-destructive testing and analyses carried out for a brick masonry building from the 19th century, which has many irregularities that involve a lack of inspections and tests of its technical condition for many years, as well as a failure to carry out necessary repairs. The conducted organoleptic tests enabled the most significant building damage to be indicated, and its causes were determined on the basis of the results of non-destructive tests and analyses. These causes include mainly wall cracks, ceiling deflections and excessive dampness. It also contains the relationships, which were developed using non-destructive dielectric and resistive methods when testing the moisture content of the brick walls. These results may be useful for other researchers dealing with brick masonry buildings from a similar period of time. The authors' intention was to present the existing poor technical condition of the brick masonry building and indicate its causes, as well as to present that a lack of appropriate maintenance can lead to a situation in which the life or health of residents is threatened.

From the construction made in the “white box” technology, first of all tightness is required - on the structural elements there should not be any cracks or scratches, through which water could penetrate, which in consequence may lead to deformation of structural elements and even loosing of their load-bearing capacity. Among the methods enabling the location of weakened places in watertight concrete, the ground penetrating radar (GPR) method is effective because the local occurrence of water in the structure evokes a clear and unambiguous anomaly on the radargram. In addition, the GPR method allows you to indicate places where water flows without the necessity of excluding the object from use and interference in the construction layers. The designation of such locations will make it possible to undertake technical activities that can facilitate the takeover of water and thus ensure the desired load-bearing capacity and usability of the object. Using the GPR method, you can also designate places that have already been deformed – discontinuities or breaking. The article presents a case study of investigations that determine the causes of leakage of tunnels made in the “white box” technology in: twice within the bottom slab of the tunnel (1 GHz air-coupled and 400 MHz ground-coupled antenna) and once in the case of tunnel walls (1.6 GHz ground-coupled antenna).

The paper presents an example of the application of vibratory machining for castings based on the results of visual testing. The purpose of the work is to popularize non-destructive testing and vibratory machining as finishing process, especially in the case of cast objects. Visual testing is one of the obligatory non-destructive tests used for castings and welded joints. The basic requirements concerning the dimensional accuracy and surface texture of cast components are not met if visible surface flaws are detected. The tested castings, which had characteristic traces of the casting process, were subjected to vibratory machining. The machining with loose abrasive media in vibrating containers is aimed at smoothing the surface and reducing or completely removing flashes. To complement the visual testing were also conducted research on the contact profilometer Taylor Hobson PGI 1200. Particular attention was focused on measuring the height of flashes and changes in the surface of smoothed details based on BNIF No. 359 touch-visual patterns. Based on the work, it can be concluded that vibratory machining allows for removal flashes and smoothing of the surface of aluminum alloy cast objects.