Vojtěch Václavík

The growing production of construction and demolition waste has been stimulating the need to look for sustainable alternatives to natural aggregate used in the production of cement composites. This study evaluates the potential use of recycled brick material as a substitute for natural coarse aggregate in terms of environmental safety, mechanical properties, the solidification effect of the cement matrix, and life cycle assessment (LCA). Recycled brick materials sourced from four recycling yards were characterized using physical, chemical, and leaching tests. Cement composites containing 50%, 70%, 80%, and 100% replacement of natural coarse aggregate with recycled brick material were subsequently designed. The results demonstrated significant variability in the environmental properties of the recycled materials depending on their origin. Compressive strength after 28 days ranged from 31.8 to 36.2 MPa, and all mixtures met the requirements for strength classes C20/25 to C25/30 according to ČSN EN 206+A2. At the same time, a significant solidification effect of the cement matrix was confirmed, leading to a reduction in the concentrations of dissolved substances by 68.0–80.1% and sulfates by 97.8–99.2% compared to the original recycled material. A life-cycle assessment demonstrated a gradual reduction in the environmental impacts as the proportion of recycled brick material increased, with the best results achieved by a mixture with 100% replacement of natural aggregate. The results confirm that recycled brick material can be safely used as a full-fledged substitute for natural coarse aggregate while maintaining the required mechanical properties and reducing environmental impacts.

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The 5th International Conference on Advances in Environmental Engineering (AEE 2025) was proudly organized by the Faculty of Mining and Geology at VŠB-Technical University of Ostrava, Czech Republic, in partnership with the Faculty of Civil Engineering at the Technical University of Košice, Slovak Republic

The aim of this research was to evaluate the impact of revitalization measures implemented in the catchments of the Vortovský Stream and the Valčice Stream, located within the protected landscape area of the Žďárské vrchy in the Pardubice Region, Czech Republic. The assessment was conducted using rainfall–runoff models HEC-HMS 4.13(The Hydrologic Engineering Center’s-Hydrologic Modeling System) and MIKE SHE version 2020 (MIKE System Hydrological European), and hydraulic models HEC-RAS 6.6 and MIKE 11 version 2020. The study focused on comparing the effects of revitalization on flow velocity in the Valčice Stream with its original state, evaluating the ability of the reconstructed ponds Malý Černý and Velký Černý to transform flood waves, and assessing the overall effectiveness of the revitalized areas in water retention within the landscape. The results demonstrate that the reconstruction of the ponds on the Valčice Stream significantly contributed to the safe transformation of flood flows, and that the revitalization of part of the stream resulted in a reduction in flow velocity in the channel. Furthermore, the revitalization measures in the Vortovský Stream catchment were found to have a positive effect on enhancing water retention in the area.

This article deals with the potential use of by-products from Třinecké železárny company—namely steelworks slag and spent foundry sand (SFS)—as an alternative to natural aggregate in the production of high-strength concrete. The aim of the study was to design and experimentally verify two concrete mixtures. For the first mixture (Mixture 1), natural aggregate was fully replaced by steelworks slag. For the second mixture (Mixture 2), the replacement was made by a combination of steelworks slag and SFS in the same volume ratio. The results have shown that Mixture 1 achieved a strength class of C70/85 and was classified as high-strength concrete. In contrast, Mixture 2, despite optimization of the composition, only achieved a strength class of C35/40, which does not allow for its classification as high-strength concrete.

This study aims to provide a comprehensive assessment of the ecological status of two distinct sections of the Bílovka stream located in the Moravian-Silesian Region of the Czech Republic. The evaluation was conducted using the standardized HEM 2014 methodology, which assesses seventeen hydromorphological indicators across three spatial zones: the channel, the bank/riparian zone, and the floodplain. A comparative analysis between a near-natural reach and a section significantly modified by human activities revealed notable differences in ecological quality. The findings underscore the practical relevance of the HEM 2014 methodology for evaluating the current hydromorphological condition of watercourses and for informing the design of targeted restoration measures, particularly within urbanized landscapes.

This article discusses the selective demolition of a family house in Ostrava Hošťálkovice carried out by the construction company Tomáš STRAUB s.r.o. This selective demolition of the building was carried out in order to map the economic impact of selective demolition and the subsequent recycling process of the waste obtained in normal construction practice. The aim of the article is to familiarize readers with the economic impact of selective demolition and its influence on the method of execution, including the economic motivation of the execution subjects. At the same time, the article also compares the economic impact in other regions of the Czech Republic based on the input data obtained.

This article deals with the possibility of using a recycled aggregate from railway ballast and platforms for the production of cement composites with a full or partial replacement of natural aggregates. This study evaluates the physical and mechanical properties of fresh and hardened concrete, as well as its resistance to water pressure, microstructure, and environmental safety. Four concrete recipes using an aggregate at the end of its life cycle from railway ballast (0/25 mm) and from the layers under the asphalt covering of the platforms (0/32 mm) were designed, with a 100% replacement for 0/25, 55% replacement (coarse fraction) for 0/32, and 45% sand for 0/4. The results have shown a significant influence of the type of aggregate on the strength, bulk density, and watertightness of the concrete. At 28 days, the compressive strengths of mixes R250, R400, R250N, and R400N were approximately 8, 20, 30, and 35 MPa, respectively, while after 90 days they increased to 10, 22, 37, and 45 MPa. The corresponding fresh concrete bulk densities ranged from about 1.95 to 2.27 g/cm³, and the water penetration depths ranged between 16 mm (best) and 27 mm (worst) among the mixes. Analyses of aqueous leachates have confirmed that the cement matrix effectively stabilizes the contaminants contained in the recycled aggregate and that the resulting products comply with the legislative limits. This study shows that an aggregate at the end of its life cycle from railway ballast and platforms can be effectively used to produce sustainable cement composites (concrete) with suitable mechanical properties and minimal environmental risks.

This article deals with the design of a technically, legislatively, and economically balanced sewerage system for the municipality of Ropice, which has long lacked a central sanitary sewer system. On the basis of the analysis of the territorial conditions, hydro-technical calculations, and legislative requirements, two potential solutions are compared—a decentralized domestic WWTP and a central separate sewerage system with a treatment plant. The final concept favors the central solution in order to ensure operational reliability, sustainability, and the possibility of using grants. This study provides a model example of an applicable solution for rural settlements with similar wastewater management problems.

Cork-derived biochars produced by slow pyrolysis (C-SP) and microwave-assisted pyrolysis (C-MWP) were evaluated for the removal of hexavalent chromium [Cr(VI)] from aqueous solutions. The materials were characterized by proximate/elemental analysis, N₂ physisorption (BET), thermogravimetry and FTIR. C-SP exhibited a higher specific surface area (174.5 m²·g⁻¹), a larger micropore volume and stronger O–H/C–O surface signatures than C-MWP, which showed partial aromatization and less-developed texture. Batch equilibrium adsorption experiments at pH 2.0 with initial Cr(VI) concentrations of 5–150 mg·L⁻¹ and kinetic experiments (c₀ = 40 mg·L⁻¹) were analyzed by nonlinear fitting to standard isotherm and kinetic models. The experimentally observed maximum uptakes were qmax,obs = 32.7 mg·g⁻¹ (C-SP) and 35.9 mg·g⁻¹ (C-MWP) at pH 2.0. Under screening conditions (pH 1.1, 45 min), removals reached 72% (1.44 mg·g⁻¹) for C-SP and 87% (1.73 mg·g⁻¹) for C-MWP. The Freundlich model provided the best fit to the equilibrium data for C-SP, consistent with adsorption on an energetically heterogeneous surface, whereas for C-MWP the fitted isotherm models did not yield physically meaningful parameters. Kinetic modeling showed rapid initial uptake consistent with energetic heterogeneity of surface sites. However, kinetic fits alone do not determine whether uptake is dominated by physical adsorption, chemical binding or redox reactions; direct surface/speciation analyses would be required to substantiate mechanistic assignments.