Silicate composites have very low conductivity in general. It is possible to achieve an electrical resistivity decrease by adding an electro-conductive filler. The conductive mixture consists of cementitious binder, various types of silica sand, and graphite-based conductive fillers. One of the research focusses is partial substitution of ordinary raw materials by alternative components (waste materials by-products and secondary raw materials) and its influence on composite properties. The alternative components studied were fly ash as a partial binder replacement, waste graphite from two different sources and steel shavings as a substitute for conductive filler. Resistivity of cured conductive silicate-based specimens was analysed in relation to changes in physico-mechanical properties in context of microstructural changes in the hardened cementitious matrix (by optical and scanning electron microscopy with energy disperse analysis). Partial substitution of cement by fly ash was found to reduce the electrical resistivity of the composite. Some of the waste graphite fillers significantly reduce the resistivity of the cement composite and increase the compressive strength. It was proven, that is possible to replace primary conductive fillers by secondary raw materials.

Electroconductive cement-based composites are modern materials that are commonly used in many industries such as the construction industry, among others. For example, these materials can be used as sensors for monitoring changes in construction, grounding suspension, and resistance heating materials, etc. The aim of the research presented in this article is to monitor the impact of carbon particle character on cement-based electroconductive composites. Four types of graphite were analyzed. Natural and synthetic types of graphite, with different particle sizes and one with improved electrically conductive properties, were tested. For the analysis of the electrical conductivity of powder raw materials, a new methodology was developed based on the experience of working with these materials. Various types of graphite were tested in pure cement paste (80% cement, 20% graphite) as well as in a composite matrix, which consisted of cement (16.8%), a mixture of silica sand 0–4 mm (56.4%), graphite filler (20.0%) ground limestone (6.7%) and super plasticizers (0.1%). The resistivity and physical-mechanical properties of the composite material were determined. Furthermore, the resistivity of the test samples was measured with a gradual decrease in saturation. It may be concluded that graphite fillers featuring very fine particles and high specific surface are most suitable and most effective for creating electrically conductive silicate composites. The amount, shape and, in particular, the fineness of the graphite filler particles thus creates suitable conditions for the creation of an integrated internal electricity-conductive network. In the case of the use of a coarse type of graphite or purely non-conductive fillers, the presence of an electrolyte, for example, in the form of water, is necessary to achieve a low resistivity. Samples with fine types of graphite fillers achieved stable resistivity values when the sample humidity changed. The addition of graphite fillers caused a large decrease in the strength of the samples.

When developing new insulating materials, there is, in recent years, a pressure to replace the widely used polystyrene insulation for material, which is more sustainable and more eco-friendly. The shelf life of ETICS insulation on a building is around 25 – 30 years and that with proper care and repairs. When the polystyrene insulation is taken down from the building, there is a little to none chance of its recycling due to the residues of mortar and other building chemicals. When the insulation system on a building is repaired or replaced, a big advantage for the environment would be, if the main part of the system, as well as the whole system, would be biodegradable. For the sustainable building industry, the advantage is also in the source of the main raw material, as it is grown naturally instead of being chemically produced, as the polystyrene. That is the place, where the straw based insulating panel comes in. Even the use of the casein glue, which base is also natural, contributes to the environmental importance of this research. This paper if fully dedicated to the complexity of making an insulating panel of rye straw bonded with casein glue.Příspěvek je věnován vývoji izolačních panelů ze slámy, pojených kasinovým lepidlem

Cement composite materials with reduced resistivity are specialized building materials, which are constantly pushing their limits. Research into these composites requires a study of the influences of exposure conditions on resistivity. The mixes selected for the purpose of the research included the reference, pure cement mix, and mixes with proportions of graphite under and above the percolation threshold, with two different types of graphite. It was found that the resistivity of all the tested mixes decreases if moisture grows; the influence of moisture is more significant for mixes with graphite proportions below the percolation threshold. The resistivity of all the tested mixes decreases with increasing temperatures; the influence of a higher temperature (50 °C) is more significant for mixes with graphite proportions above the percolation threshold; however, these mixes are, at the same time, more resistant to permanent changes in resistivity caused by frost (−10 °C). It was found that the action of CO₂ causes a reduction in resistivity. Mixes with proportions of graphite above the percolation threshold show higher stability when exposed to CO₂. Mixes with proportions of graphite below the percolation threshold are extremely sensitive to horizontally oriented pressure loads. Increases in resistivity caused by vertical pressure loads were by 20–40%. The resistivity of the mixes with proportions of graphite above the percolation threshold was less sensitive to the pressure load.

This paper deals with hazardous waste solidification /stabilisation, specifically neutralization sludge that comes from active industrial sources and neutralization sludge that comes from old ecological sources. As solidification agents fluidized bed combustion ash, classic fly ash and ordinary Portland cement were used. According to the valid legislation and selected possible future use of solidification product a laboratory testing of proposed solidification /stabilisation recipes was performed. The results of leachability tests, unconfined compressive strength and ecotoxicological test showed that solidification product use as a technological and reclamation material on depots and setting pits is possible.Příspěvek se zabývá solidifikací/stabilizací nebezpečného odpadu, konkrétně neutralizačních kalů, které pocházejí z aktivních průmyslových zdrojů a neutralizačních kalů pocházejících ze starých ekologických zátěží. Jako solidifikační činidla byl použit fluidní a klasický popílek a portlandský cement.V souladu s platnou legislativou a s vybraným budoucím využitím solidifikátu bylo provedeno laboratorní ověření navržených receptur. Výsledky výluhových testů, pevnsoti v tlaku prostím a zkoušky ekotixicity prokázaly možnost využití solidifikátu jako technologického a rekultivačníého materiálu