Solid State Phenomena Vol. 351

Abstract: The paper deals with the production of fiber cement and the use of alternative raw materials in its production. The paper describes the basic technologies used for the production of fiber cement with a description of their advantages and disadvantages for the given type of product. The paper also describes the most commonly used types of fillers and their impact on the final fiber cement products. The paper also describes selected alternative raw materials used for the production of fiber cement and their impact on the final products. The paper describes the possible use of waste dust from facade fiber cement boards in the production of corrugated sheets. Trial recipes were designed with partial replacement of original raw materials with waste dust. The fiber-cement corrugated sheets were produced with using Hatchesk technology. Mainly was investigated the influence of the addition of waste dust on the strength characteristics and the volume weight of the final products. The produced sheets were tested according to EN 494+A1: 2016 Fibre-cement profiled sheets and fittings - Product specification and test methods. The tested samples with waste dust reached comparable results like sheets produced according to standard recipe. No negative effect was proven of the addition of waste dust on the strength characteristics of final products.

Abstract: This paper deals with the research of a new chemically resistant cement repair mortar modified with selected secondary raw materials. The aim of this work is to study the influence of particle distribution of fly ash on selected characteristics of the developed remediation material. This new mortar will be suitable for use in the extremely aggressive environment of sewers. The monitored parameters include key physical-mechanical characteristics and resistance to the attack of aggressive biogenic sulfuric acid. The chemical resistance was tested by simulating the exposure environment in laboratory conditions, according to the methodology of DIN 19573. The obtained results show that by optimizing the particle distribution of fly ash it is possible to maintain the values of physical-mechanical characteristics and improve the chemical resistance of test specimens of new repair mortar.

Abstract: This article is focused on issues of concrete behavior under high temperatures. The aim of this work is to verify the influence of the addition of organic fibres on the fire resistance of concrete. Emphasis is placed on describing the possibility of using recycled fibres from PET or cellulose due to the positive ecological impact. Based on the obtained results, it is clear that it is possible to use fibres to increase fire resistance even from sources that do not come from primary production.

Abstract: The main aim of this research was to investigate the effect of the addition of coal fly ash as a secondary waste material on the synthesis and properties of forsterite ceramics. The utilization of fly ash as a raw material, which contains flux oxides, reduce the necessary firing temperature for the synthesis of forsterite ceramics in comparison with forsterite ceramics synthetized from high purity or industrial materials, while preserving its refractory properties. The results revealed that forsterite was synthesized as a major crystalline phase in all samples. The optimal firing temperature for obtaining good physico-mechanical parameters was found to be between 1400-1600°C for high purity or industrial materials, while mixtures containing fly ash could achieve similar parameters at lower firing temperatures between 1200-1300°C. The decrease in refractoriness was found to be within acceptable limits for utilization as a refractory material. These findings demonstrate the potential for cost reduction and energy savings through the use of secondary waste materials and reduced firing temperature in the synthesis of forsterite ceramics.

Abstract: The paper focuses on developing and testing polymeric materials for the CIPP method. The CIPP (cured-in-place pipe) method is a method, that focuses on rehabilitation without excavation, especially for sewer pipes. These developed materials are then saturated in special textile sleeves, which are pulled and cured directly in the sewer. Foam waste glass, basalt filler, waste glass from solar panels, and fly ash were used as secondary fillers for the tested formulations. The secondary raw materials in these materials improve the mechanical performance of the resulting composites and, in addition, improve their environmental and economic impact. The main subject of this paper is to verify the processability of these materials and verify their application/saturation into the textile lining. In particular, the determination of kinematic viscosity, fresh density, comparison of workability, and the so-called application test. The aim is to assess the influence of the added secondary raw materials on the processability and correct application to the lining so that the results are better or comparable to the reference material or have even better properties than the mass reference. According to research, basalt filler appears to be the most suitable secondary filler.

Abstract: This paper deals with the determination of k-value and activity index for ground granulated blast furnace slag (GGBFS). The aim of this paper is to determine the activity index and k value for different CEM I cement substitutes with ground granulated blast furnace slag. determination of the k-value is based on the relationship of the water/cement ratio and the compressive strength of concrete with GGBFS. The next goal is to create a mathematical function that describes the development of compressive strength depending on the age of the cement mortar or concrete and the amount of cement replacement with GGBFS. Based on the achieved compressive strengths were designed compressive strength function for concrete and cement mortar with high coefficient of determination (above 0.9). Furthermore, k-values were determined for different ages of concrete and replacement of cement with finely ground slag. These k-values increase as the age of the concrete increases.

Abstract: Electrically conductive composites based on silicates offer new possibilities for the use of composites not only in civil engineering but in the construction industry in general. These materials can be used, for example, for resistive heating of roads and highways, surge protection for buildings, EMI shielding, or smart sensors. This article focuses on cement composites where graphite powders are used as electrically conductive fillers. The research focuses on the behaviour and the change of the electrically conductive properties of these materials under mechanical loading. The changes in the resistivity of the composites when loaded in different directions on the electric current flow was investigated and studied. The specimens were loaded in the direction of electric current and in the direction perpendicular to the electric current.

Abstract: This article deals with the selection of a suitable gelling agent for refractory castable with a sol-gel binder system. The goal is to find the optimal ratio between gelation time, content, and concentration of the solution. Various salts (NaCl, NH₄Cl, Ca(NO₃)₂) are investigated as gelling agents. Gelation curves are constructed from gelation time observations. For the design of the formula of refractory castable with a sol-gel bond, it is important to know the behavior of the sol after mixing with the gelling agent. This is the goal of the experiment. In the end, we will obtain initial data for further proposals for the composition of refractory castable with a sol-gel bond.

Abstract: Measuring humidity in building materials is of great importance in assessing the condition of materials and also in building diagnostics, as the presence of humidity affects their physical and thermal insulation properties. In the construction industry, the use of non-destructive electrical measurement methods for testing the physico-chemical properties of materials is common and especially the electrical conductivity of materials is significantly affected by humidity.