This study examines the verification of the mechanical properties of ordinary concrete with Portland cement (OPC) and high-performance concretes (HPCs) after exposure to the effects of varying temperatures, in addition to durability tests as part of the experimental testing. Particular emphasis is placed on the comparison between OPC and HPC. Before describing the behavior of concrete under the influence of heat and the difference between ordinary and high-performance concrete, the microstructures of both hardened mixtures were monitored, and the chemical compounds of the used Portland cement and silica fume were analyzed using a scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR). For the experiments, compressive strength and flexural strength tests were performed before and after stressing at elevated temperatures. Furthermore, the experiments included the following: a study of concrete color changes under the influence of elevated temperatures, the use of the ultrasonic pulse method, the determination of resistance to water and chemical de-icing agents, and an examination of the frost resistance of concrete. This study considers the differences between the two concretes—OPC and HPC—especially in terms of their mechanical properties, as well as their durability and resistance to chemicals. This research contributes to the understanding of the properties of the two types of concrete; subsequently, it can help in the selection of concrete for specific applications.

Although both beryllium and its compounds display high toxicity, little attention has been focused on the removal of beryllium from wastewaters. In this research, magnetically modified biochar obtained from poor-quality wheat with two distinct Fe_xO_y contents was studied as a sorbent for the elimination of beryllium from an aqueous solution. The determined elimination efficiency was higher than 80% in both prepared composites, and the presence of Fe_xO_y did not affect the sorption properties. The experimental q_max values were determined to be 1.44 mg/g for original biochar and biochar with lower content of iron and 1.45 mg/g for the biochar with higher iron content. The optimum pH values favorable for sorption were determined to be 6. After the sorption procedure, the sorbent was still magnetically active enough to be removed from the solution by a magnet. Using magnetically modified sorbents proved to be an easy to apply, low-cost, and effective technique.

Arguably the most important element in the sustainability of concrete development is the discovery of an optimal sustainable binder and substitution for the increasingly depleted reserves of natural aggregates. Considerable interest has been shown in alkali-activated materials, which possess good characteristics and could be considered environmentally friendly because of their use of secondary materials in production. The aim of this study was the determination of the mechanical properties of three different mixtures based on the same locally accessible raw materials. The reference mixture contained Portland cement, the second mix contained a finely ground granulated blast furnace slag instead of cement, and the third mixture contained a portion of light artificial aggregate. The experiments focused on the testing and mutual comparison of the processability of the fresh mixture and mechanical characteristics (like compressive and flexural strength, as well as resistance to high temperatures and surface layer tear strength tests). Reinforced concrete beams without shear reinforcement and with three levels of reinforcement were also tested with a three-point bend test. The results show that, overall, the mechanical properties of all the tested mixtures were similar, but each had its own disadvantages. For example, the blast furnace slag-based mixture had a more vulnerable surface layer or a debatable loss of bulk density in the light aggregate mix at the expense of the mechanical properties. One of the main results of the research is that it was possible to technologically produce beams from the alkali-activated concrete (AAC) mixture. Then, the performed beam experiments verified the mechanism of damage, collapse, and load capacity. The obtained results are essential because they present the use of AAC not only in laboratory conditions but also for building elements. In beams without shear reinforcement, the typical tensile cracks caused by bending and shear cracks appeared under loading, where their character was affected depending on the degree of beam reinforcement and loading.

A novel N-doped carbon material was obtained using a CVD-like procedure by depositing medium-sized pyridine-based molecules on copper-based substrates.