Strata Mechanics Research Institute

The aim of this study was to analyze properties of natural and waste-containing porous materials intended for use in construction. Experiments using the hydrostatic buoyancy method were conducted to assess the fundamental characteristics of studied samples that include bulk density, porosity, and water absorption. The investigation focused on the behavior of both natural and laboratory-prepared porous materials subjected to water absorbability measurement. The time required for complete saturation process with water was determined, together with the minimum saturation time that still ensured satisfactory measurement accuracy. For composite-cement stones, the results of bulk density measurements and the characterization of pore space, including total, open, and isolated porosity, were analyzed. Based on the findings, practical recommendations were proposed regarding the displacement procedure and the interpretation of results obtained during the determination of absorbability of materials with complex internal structures. The conclusions drawn from the research conducted are crucial for environmental protection, as they contribute to better characterization and assessment of the quality of products with a smaller negative impact on the planet.

HighlightsWhat are the main findings?Bottom ash (BA) demonstrates strong potential for use as a secondary binder in sustainable construction materials.Smaller particle size increases compressive strength.Thermal treatment at 1000 °C improves binding activity and raises water permeability values.The mechanical performance of BA-based composites is primarily controlled by chemical activation.What are the implications of the main finding?Bottom ash can be reused in sustainable construction.Proper pretreatment enhances the reactivity of BA-based composites.The results demonstrate that proper thermal treatment can transform BA into a reactive component suitable for cementitious systems.The growing demand for sustainable and circular construction materials has increased interest in reusing by-products from municipal solid waste incineration. Due to the variability in the chemical composition of bottom ash (BA) between different plants, sampling seasons, and particle sizes, an individualized approach depending on its origin is essential. This study examines the potential of BA as a binding material in composite structures. Composites were prepared from BA fractions of different granulometries, including ground and thermally treated material. Compressive strength tests and structural analyses of density, porosity, and water permeability were performed to evaluate the influence of particle size and heat treatment on binding activity. The results show that smaller particle sizes significantly improved compressive strength, while the highest strength was obtained for samples calcined at 1000 °C, with an average increase of 84% compared to untreated material. Thermal treatment enhanced binding activity through the mobilization of hydration-active compounds bound in non-reactive mineral phases formed during water cooling and also increased water permeability due to the breakdown of porous structures. These findings confirm the potential of BA as a secondary binder in construction materials; however, further research is needed to improve its reactivity and mechanical performance.

Conducting mining operations in fault zones is a very challenging task, both from a technological perspective and also due to the safety of the miners. Therefore, it is essential to determine the impact of mining parameters on the possibility of fault activation, which in many cases leads to high seismic activity. The article presents the results of numerical analyses of the impact of longwall mining in the vicinity of tectonic faults on the state of stress in the rock masses. The authors demonstrated the influence of the advancement of the longwall face and its direction on the risk of rock burst, both for mining conducted in the footwall and hanging wall.

The article presents concepts and experimental studies for an energy harvester designed to convert short, pulsating, turbulent airflows into electrical energy. Such flows occur in the vicinity of roads, highways, and railway tracks, among other places, and are caused by passing vehicles. A laboratory prototype is built in the form of a pendulum deflected from an equilibrium position by the airflow. The pendulum’s oscillations are converted into electrical energy using an electrodynamic transducer. The harvester uses a magnetic system that increases the frequency of the oscillations and increases the energy efficiency of the system. The harvester can be used to power local low-power electrical devices, such as highway monitoring systems. It is possible to place a set of multiple harvesters in the vicinity of the road, creating a visual effect of reeds waving in the wind.

The present work aims to analyse the influence of present-day burial depths of coal seams on the sorption properties towards CH4 and CO2, respectively. For medium-rank coals located in the southwestern area of the Upper Silesian Coal Basin (USCB), the gravimetric sorption measurements were carried out with pure gases at a temperature of 30 °C. The variability of CO2/CH4 exchange sorption and diffusivity ratios was determined. It was revealed that in coal seams located at a depth above 700 m, for which the sorption exchange ratio was the greatest, the process of CO2 injection for permanent storage was more beneficial. In the coal seams lying deeper than 700 m with a lower CO2/CH4 sorption ratio, the CH4 displacement induced by the injection of CO2 (CO2-ECBM recovery) became more favourable.

Slags and ashes generated in thermal waste treatment facilities require proper management. In line with the principles of the circular economy, new, more economical and ecological possibilities for utilizing these substances are sought. These waste materials exhibit characteristics similar to rocks in many aspects. This study focuses on analyzing the similarities and differences between nine selected rocks and three samples of slags and ashes obtained from municipal waste incineration. The main research device used was a polarizing microscope, using reflected, transmitted and fluorescent light. Additionally, low-pressure gas adsorption equipment, as well as helium and quasi-liquid pycnometers, were used for complementary analysis. The parameters analyzed mainly covered broadly defined petrographic properties of rocks and slags, with a particular emphasis on porosity, porous structure and the spatial distribution of pores and fractures. The conducted analyses confirmed a significant similarity between slags and ashes and clastic sedimentary rocks such as sandstones and mudstones. The research results underscore the importance of petrographic microscopic studies for analyzing materials other than rocks. They also allow for exploring applications for slags and ashes in areas traditionally reserved for natural rock resources. The findings also indicate the necessity of using methods other than microscopic ones to describe the pore space of rocks. The lower measurement range of the optical microscope is limited to approximately 1 μm, covering only macropores. Other methods extend this characteristic to micro- and mesopores. Therefore, a combination of different methods is often employed to obtain a more comprehensive characterization of rock porosity.

MeasureMents of the Methane ConCentration along the longwall exCavations and longwallone of the most hazardous places in mines are longwall areas.they emit a considerable amount of methane to the ventilation air. the emission depends on many but mostly known factors.the article presents the research results on changes in the methane concentration along the longwall excavations and longwall.the distributions were obtained based on a measurement experiment at the Zg Brzeszcze mine in Poland.the author's research aimed to experimentally determine the concentration of methane as a function of the length of excavation for the longwall excavations and longwall.As a result, methane concentration trends along the excavations were obtained.the conclusions show the pros and cons of the method used, and it allows to set the right direction in the development of measurement systems and sensors.

The paper presents the results of assessment studies of the time course for technical wear in masonry buildings located in the area of mining-induced ground deformations.By using fuzzy inference system (FIS) and the "if-then" rule, corresponding language labels describing actual damage recorded in structure components were translated into scalar outputs describing the degree of damage to the building.Adopting this approach made it possible to separate damage resulting from additional effects coming from mining--induced ground deformations and the natural wear and tear of masonry structure.By using statistical analysis an exponential function for the condition of building damage and the function of natural wear and tear were developed.Both phenomena were subject to studies as a function of time regarding the technical age of building structure.The results obtained were used to develop a model for the course of technical wear of traditionally constructed buildings used within mining areas.In the course of natural wear and tear buildings located in mining areas are additionally exposed to forced ground deformations.The increase of internal forces in structure components induced by those effects results in creating an additional stress factor and damage.The hairline cracks and cracks of building structure components take place when the intensity value of mining effects becomes higher than the component stress resistance and repeated effects result in the decrease of structure rigidity.The observations of building behaviour in mining areas show that the intensity of mining activity and the multiplicity of its effect play a substantial role in the course of technical wear of buildings.The studies show that the level of damage resulting from mining effects adds up to natural wear and tear of the building and impairs the global technical condition as compared to similar buildings used outside mining areas.