The efficient classification of materials in construction debris is crucial for their sorting and further valuable utilization. Current methods, whether relying on force sorters or separators, are reaching their limitations. In many cases, construction and demolition waste materials end up being downcycled or even sent to landfills. Our contribution is divided into two parts. The first part presents facts relating to the production of construction and demolition waste in the EU and justifies the urgency of responsible waste management. It also recaps the development of indirect methods of classification and briefly describes types of suitable sensors for material observation and algorithms for data evaluation. The second part describes our classification solution, developed by the faculties of civil engineering and electrical engineering at CTU in Prague. This method is based on the evaluation of data obtained with ordinary RGB cameras.

The efficient classification of materials in construction debris is crucial for their sorting and further valuable utilization. Current methods, whether relying on force sorters or separators, are reaching their limitations. In many cases, construction and demolition waste materials end up being downcycled or even sent to landfills. Our contribution is divided into two parts. The first part presents facts relating to the production of construction and demolition waste in the EU and justifies the urgency of responsible waste management. It also recaps the development of indirect methods of classification and briefly describes types of suitable sensors for material observation and algorithms for data evaluation. The second part describes our classification solution, developed by the faculties of civil engineering and electrical engineering at CTU in Prague. This method is based on the evaluation of data obtained with ordinary RGB cameras.

The article presents a project submitted by TAČR in the Environment for Life section 2. The goal of the project is to find the application of recycled glass fractions from photovoltaic panels in the field of construction. The project focuses on three basic silicate building materials, which are able to incorporate glass recyclate shards into their structure during the hydration, firing and melting process. The paper specifies the first results of testing possibilities for use of glass recyclate from photovoltaic panels for concrete masonry units. It compares particular recipes and its physical and mechanical properties with the main focus on the compressive strength. It then compares the values of these recipes with the values of commonly used composite materials for masonry units without recyclates.

The paper discusses the possibilities of diagnosing historical masonry structures by using non-destructive and destructive testing methods. First, the compressive strength of the masonry elements and the compressive strength of the mortar are determined, then the characteristic compressive strength of the masonry is calculated. It is important to assess the bond of the masonry and determine the presence of cracks. Finally, the moisture content and salinity of the masonry shall be determined.

The contribution focuses on the current topic of the replacement of historical burnt bricks in heritage-protected buildings. It presents the possibilities of selecting an adequate replacement by recycling historical masonry elements taken from demolished buildings while meeting the requirements placed on current masonry elements with an emphasis on their durability. A resonance method for classifying bricks into quality groups is presented here, along with basic aspects characterizing bricks from different historical periods, which represent another criterion for assessing their suitability for use in historical constructions.

Plastic waste in the construction industry can consist of various plastics such as polyethylene, polypropylene, PVC, ABS, polystyrene, polycarbonate. Plastic waste in construction can come from packaging, insulation and other materials. Plastic waste not generated in the construction industry is also recoverable. The best way is to recycle plastic waste into materials that can be used for building materials, fillings, structures, etc. They can also be used in the production of lightweight concrete.

In our practice, we often face the question of building stone provenance on historic buildings. However, methods providing relevant answers to this question are mostly of a destructive character requiring sampling. Therefore, our research has focused on the use of reflectance spectrometry, which is a very promising and effective non-destructive method. This paper discusses the basic principles and possibilities of this method with regard to its application to historic buildings and decorative stone.

The contribution summarizes the fundamental chapters of the transported standard to re-demolition audit and building dismantling as a standard procedure for structure removal. The purpose of the standard will be to prescribe how the pre-demolition audit should proceed, what information it should contain, and how the deconstruction of the building should take place, in order to achieve the maximum possible utilization of the obtained materials. The motivation is primarily the return of quality raw materials to production and the reduction of primary resource extraction, which is one of the goals of sustainable development.

The paper deals with the analysis of mineral construction and demolition waste management in the Czech Republic between 2007 and 2022. The analysis is based on data from the Czech Environmental Information Agency. It has been shown that the production of recycled mineral construction and demolition waste has quadrupled in this period and that the share of recycled mineral construction waste in the market of mineral materials for the construction industry is around 15%.

The main theme of this paper is the usage of the advanced time-dependent elasto-plastic material model for diaphragm walls modeling. First, a theory of time-dependent behaviour is briefly introduced. Next, the Shotcrete material model is described and calibration of materiál model in long term conditions based on laboratory testing is done. Finally, a real boundary value problem of deep excavation supported by diaphragm walls with the strut is solved. Reached values of intemal forces and deformations reached using different modelling methods are compared and discussed.

The paper focuses on the issue of permitting the construction of apartment buildings in the period of the First Republic, with a focus on the then building regulations. The paper uses the example of the construction of a specific apartment building in Brno to present the then system of building permits, selected technical requirements for the construction of apartment buildings, including the cost of permits and the possibility of obtaining a state contribution for construction.

In the presented paper, the results of the use of modified gypsum-based recyclate obtained from construction and demolition waste are analyzed. The selected recyclate comes from a real construction site of Moravostav Brno, a.s. and was subjected to modifications using a newly developed gypsum plasterboard recycling line. During the research, the influence of the recyclate treatment, especially in terms of grinding fineness, on the key properties of the dry gypsum mixture was monitored. Substitution of gypsum (or gypsum binder) in the mix was carried out in proportions of 10, 25 and 50 wt%. The resulting properties, such as bulk density, flexural tensile strength, compressive strength, volumetric changes and shrinkage, were monitored after 7 days of sample production.
In a follow-up step, gypsum blocks using treated gypsum recyclate and the designed dry gypsum slurry were semi-produced at Moravostav Brno, a.s. in January 2024. A segment of the wall was constructed from the blocks.
The results obtained clearly show that with appropriate treatment, it is possible to effectively replace part of the gypsum binder in the dry gypsum mixture using modified gypsum recyclate. These findings provide important information for the advanced use of gypsum plasterboard recycling in the construction industry, while highlighting the potential for more sustainable and environmentally friendly practices in building materials.

This article deals with the possible combination of high temperature fly ash with fluidized fly ash. The aim of this experiment is to verify the influence of the combination of these two secondary energy products not only on the parameters of cement mortar in its fresh state, but especially on its mechanical parameters in its hardened state.

By digitizing and automating processes throughout the building life cycle, the goal is to optimize the use of information so that it can be easily used either to reduce waste from buildings (waste prevention) or to have sufficient information about the materials and products used in the building at the end of its life cycle or as part of various renovations or retrofits. At the same time, improving the planning and management of the waste generated is a key effort. The paper presents the results of the European RECONMATIC project in this area, which progressively links information efficiency approaches with BIM processes. As such, the project has a broader focus and represents a paradigm shift in the management of C&D materials, from the traditionally conservative approach to C&D waste, to a similarly conservative approach of the construction industry, to construction production that seeks to achieve high waste recovery rates, and to the adoption of a responsive approach to waste recovery. The technologies to be used in this project (creating and working with a digital twin of the building, blockchain-based applications, precision prefabrication, efficient sorting through automation and robotics, etc.) are part of the themes that the project focuses on.

This paper presents research focused on studying the behaviour and properties of wood-cement composites under changes in relative humidity. The behaviour and the resulting changes in properties with variations in air (relative) humidity are significantly influenced by the chips contained. The chips are mineralised or stabilised during the manufacturing process. The by-product (particle mixture) from the production of cement-bonded particleboards, which was used to modify the composition of the composites, already contained mineralised spruce chips (i.e. stabilised properties and structure). The goal of the research was to study the sorption mechanisms in terms of dimensional and volumetric changes, including the assessment of the composite materials' performance properties (density, strength characteristics and modulus of elasticity). Thus, the influence of spruce chips stabilization in terms of different matrix compositions of the composites was also partially, indirectly analysed. Three variants of composites were tested - 2 types of reference (based on Portland and blended cement); 1 type with modification of the binder and filler with particle mixture produced during the production of cement particleboards (4% cement substitution, 4% substitution of primary chips). For the determination of each point of the sorption curves, the test bodies were always exposed to a given moisture content for a period of time to allow their mass to settle. The sorption isotherms indicate the different behaviour of the plates during the increase and decrease of the ambient air humidity. Differences were also observed in the case of hysteresis. The modification of the composition of the mixture for the production of cement-bonded particleboards has an effect, among other things, on the stabilisation of the spruce chips. The changes in physical and mechanical properties are practically negligible in terms of the practical use of the boards with modified composition.

This article deals with the possibility of assessing the k-value of power plant fly ash using durability. For cement mortars with replacement of 10, 20 and 30 % of Portland blended cement with fly ash, compressive strengths, efficiency indices, depth of talc water seepage and depth of carbonation were determined for ages of 7, 28, 60 and 90 days. For individual cement substitutes, k-values were determined for a given age using the relationship between water coefficient and compressive strength. According to the results of the hardness tests, the determined k-values were assessed and the k-values that are safe for the use of power plant fly ash in the aggressive environment XC and XD were determined.

This article follows up on Part 1, which dealt with the theoretical knowledge of partial fire protection of steel structures. It focuses on experimental work and numerical models, supplemented by parametric studies. Experiments were conducted on four steel samples, each subjected to a standard fire temperature curve for 60 minutes. The samples were tested with various thicknesses of coatback to determine its impact on the thermal behavior of steel. Numerical models were developed based on the experimental data and used for parametric studies, which examined the impact of various variables, such as the length and thickness of fire protection, on the temperature at the junction of the beam and column. The results show that the thickness and length of fire protection significantly influence the thermal stability of steel structures and can be used to design effective fire protection measures.

This article focuses on the partial fire protection of steel structures and provides a theoretical review of current methods and materials used in this area. Various types of passive fire protection systems are introduced, including intumescent coatings and their influence on heat transfer between protected and unprotected parts of the structure. The article deals with analytical and mathematical methods for determining the thermal properties and fire resistance of the materials used, with an emphasis on those that undergo thermal degradation. This article offers a comprehensive view of the theoretical foundations of partial fire protection of steel structures and proposes directions for further research in this area, providing a basis for Part 2: Experiments, Numerical Models, and Comparisons.

The article is focused on the issue of traditional timber joist floor structures and floor compositions from the period up to the first half of the 20^th century. In building practice, we very often encounter these structures in residential buildings that are the subject of structural changes. During these interventions, the basic ideas of the original technical solution are not always respected and some physical parameters of building are degraded. The article describes the principles that were devoted to these types of structures in historical legislative and standard regulations and further in professional literature. The original historical solutions are presented on a practical example. In relation to building interventions in historic timber joist floor structures, current legislative and standard regulations are described, as well as examples of modern solutions and their limitations.