This paper is focused on the permeability of cement composite samples with various admixtures. Permeability was examined by the rapid chloride permeability test due to the simple and relatively quick performance among the many methods. Permeability is one of the durability parameters considering the pore system of the composite structure. Ion diffusion provides information about inner pore structure by passing a charge through the sample. In real-life conditions, not only chlorides but also other ions can penetrate into the structure and cause corrosion. Various cement supplements were used as admixtures. The reference sample consisted of cement, fine sand, and water, while the rest of the samples consisted of 20% blast furnace slag, bypass dust, eggshells or recycled glass instead of the cement. The results showed lower permeability in samples containing blast furnace slag and eggshells and a higher charge passage in samples with recycled glass and bypass dust than for the reference sample.

Mine effluents represent a serious environmental problem on a global scale. Therefore, the effective treatment of this water is a serious issue in the scientific field. The adsorption process seems to be one of the attractive methods, especially due to the simplicity of design, affordability or high efficiency. The latest scientific knowledge has shown that the use of waste and natural adsorbents is economical and effective. This study aimed to evaluate the efficiency of the adsorption process of natural and waste materials—zeolite, bentonite and fly ash—under the influence of temperature and modification of these adsorbents. The novelty of this study resides in an adjustment of the modification method of adsorbents compared to previous research: thermal–alkaline treatment versus hydrothermal one. Another novelty is the use of modified fly ash from biomass combustion as an adsorbent in comparison with the previously used fly ash from coal combustion. The modification of the adsorbents made the adsorption process more effective at all experimental concentrations. The characterisation of adsorbent samples was performed using X-ray diffraction (XRD). The parameters of the adsorption isotherms, Langmuir, Freundlich and Temkin, were estimated by nonlinear regression analysis. The adsorption capacity of Cu(II) of fly ash was comparable to natural adsorbents. Adsorption processes were better described by pseudo-second-order kinetics. At the end of this study, the suitability of using the adsorbents to reduce the concentration of Cu(II) in neutral mine effluents was observed in the following order at 30 °C: unmodified fly ash > modified bentonite > unmodified zeolite. At the temperatures of 20 °C and 10 °C, the same trend of the suitability of adsorbents use was confirmed: modified bentonite > modified zeolite > modified fly ash. The practical applicability of this study lies in the expansion of knowledge in the field of adsorption processes and in the improvement of waste management efficiency of heating plants not only in Slovakia, but also globally.

This study investigates the performance of cement composites incorporating waste materials—blast furnace slag, bypass dust, eggshells, and recycled glass—as partial replacements for cement, following their exposure to sulphate attack in a corrosion chamber. It assesses changes in compressive strength, water absorbency, specific surface area, and degree of hydration post-exposure. A point evaluation system was used to compare the samples based on their resistance to the aggressive environment and the resultant property changes. While scoring differences among the samples were minimal, the reference sample without waste, slag sample and eggshells sample exhibited the best overall performance, whereas the glass- containing sample was the least effective. These results enhance our comprehension of the feasibility of employing specific waste materials as sustainable alternatives in cement composites.