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In this study, the potential of use of waste diatomaceous earth from production of diatomaceous earth for filtration purposes, as an alternative raw material for foam glass production, was explored. The Chemical and mineralogical composition, and the high temperature behavior of waste diatomite were studied to assess the suitability of this material for foam glass production. Glass-ceramic foams were prepared using NaOH solution as foaming agent, via hydrate mechanism. The Influence of different pretreatment and firing temperatures on the foam’ structure, bulk density and compressive strength was investigated. High temperature behavior was studied using TG/DTA analysis and high temperature microscopy. Phase composition was studied using X-ray diffraction analysis. Glass-ceramic foam samples of high porosity comparable to conventional foam glass products were fabricated. Both pretreatment temperature and foaming temperature were found to have a significant influence on foam properties. With increased pretreatment temperature pyrogenic carbon from thermal decomposition of organic matter contained in the raw material acted as an additional foaming agent and remained partially unoxidized in prepared foams. Bulk densities of prepared samples ranged from 150 kg/m3 to 510 kg/m3 and their compressive strength was between 140 and 1270 kPa.

In present study, nanosized iron oxides particles are synthetised by easy one step precipitation from Mohric salt (NH4)(2)Fe(SO4)(2)center dot 6H(2)O reacting with sodium hydroxide solution in temperature up to 60 degrees C. When changing the time of reaction, the iron oxide particles of different shape are prepared and when drying wet extracted particles at elevated temperature of 60 degrees C the change of 2D shaped morphology is observed. Depending on the time of reaction different ratios of FeOOH and Fe3O4 are obtained in this study. DTA - TGA, XRD, FTIR and SEM are used for the characterisation of particles in this study.

Phosphorus-containing heterocyclic cationic surfactants alkyldimethylphenylphospholium bromides with the alkyl chain length 14 to 18 carbon atoms were used for the stabilization of silver nanodispersions. Zeta potential of silver nanodispersions ranges from +35 to +70 mV, which indicates the formation of stable silver nanoparticles (AgNPs). Long-chain heptadecyl and octadecyl homologs of the surfactants series provided the most intensive stabilizing effect to AgNPs, resulting in high positive zeta potential values and smaller diameter of AgNPs in the range 50-60 nm. A comparison with non-heterocyclic alkyltrimethylphosphonium surfactants of the same alkyl chain length showed better stability and more positive zeta potential values for silver nanodispersions stabilized with heterocyclic phospholium surfactants. Investigations of biological activity of phospholium-capped AgNPs are represented by the studies of antimicrobial activity and cytotoxicity. While cytotoxicity results revealed an increased level of HepG2 cell growth inhibition as compared with the cytotoxicity level of silver-free surfactant solutions, no enhanced antimicrobial action of phospholium-capped AgNPs against microbial pathogens was observed. The comparison of cytotoxicity of AgNPs stabilized with various non-heterocyclic ammonium and phosphonium surfactants shows that AgNPs capped with heterocyclic alkyldimethylphenylphospholium and non-heterocyclic triphenyl-substituted phosphonium surfactants have the highest cytotoxicity among silver nanodispersions stabilized by the series of ammonium and phosphonium surfactants.

The rheological properties of alkali-activated systems are significantly affected by the nature of the alkaline activator. Hydroxide-activated systems' workability is typically lower than that of alkali-activated systems but can be improved by lignosulfonate plasticizer. However, the lignosulfonate plasticizer's effectivity depends on the dosage of lignosulfonate, the nature of hydroxide and pH of their solutions. Therefore, in this study, the effectiveness of lignosulfonate plasticizer with respect to alkali ion type (Na+, K+, Li+) in alkali hydroxide-activated systems based on ground granulated blast furnace slag was evaluated. The concentration of the alkaline activator (NaOH, KOH and LiOH) was the same in all cases of 4M. The superplasticizer dosage was 0%, 0.5% and 1.0% of dry matter of lignosulfonate plasticizer to the slag weight. Rheological properties were determined using a rotational rheometer equipped with vane in-cup geometry working in oscillation amplitude sweep mode, from which critical strain and corresponding viscoelastic variables were obtained.

Tento článek se zabývá procesem výroby anorganického pěnového skla při využití odpadní křemeliny jako vstupní suroviny. Odpadní křemelina byla nejprve podrobena analýze chemického a mineralogického složení. Pěnové sklo bylo vytvořeno pomocí práškové spékací metody lisováním do tablet za přídavku pěnícího činidla. Po výpalu bylo zkoumány vlastnosti pěnového skla pomocí rentgenové difrakční analýzy, rastrovacího elektronového mikroskopu, stanovení objemové hmotnosti a pevnosti v tlaku. Možnost využití odpadní křemeliny v surovinových směsích byla zkoumána v souladu s vlivem teploty výpalu a výslednými vlastnostmi anorganického pěnového skla., This article deals with the manufacturing process of inorganic foam glass with utilization of waste diatomite as a raw material. The waste diatomite was first subjected to an analysis of chemical and mineralogical composition. The foam glass was formed by a powder sintering method by pressing into pellets with the addition of a foaming agent. After firing, the properties of the foam glass were investigated using an X-ray diffraction analysis, scanning electron microscopy, bulk density, and compressive strength. The possibility of utilization of waste diatomite in raw material mixtures was investigated in accordance with the influence of firing temperature and the resulting properties of inorganic foam glass.

The work deals with the impact of crushed brick on properties of Portland cement binder. The source of brick recycled materials is not only the demolition waste, but also the waste from brick production. One way to reduce the amount of this recyclate is to use it in cement-based composite. The advantages of using bricks as aggregate are their lower bulk density compared to conventional aggregates. Economic and ecological benefits are also important, because less natural sources need to be mined. First, the phase composition of used brick aggregate, its particle size and morphology were analysed. Test specimens with different content of brick recyclate were prepared and tested for the mechanical properties. Subsequently, the microstructure of prepared samples was examined using a scanning electron microscope. The phase composition of samples was analysed by X-ray diffraction analysis.

Increasing utilization of secondary raw materials and alternative fuels results in increasing contents of metals in cements. Zinc is one of these elements. It comes to cement with secondary raw materials such as slag or fly ash or by the utilization of used tires as an alternative fuel. Zinc ions significantly prolong the hydration process in cement. This work deals with the influence of zinc ions in the form of very poorly soluble ZnO salt and easily soluble ZnCl2 and Zn(NO3)(2) on the hydration of cement blended with fly ash. Zinc was dosed in the range of 0.05%, 0.1%, 0.5% and 1% of cement weight. The effect of zinc on hydration was monitored by isothermal and isoperibolic calorimetry. A 15% addition of fly ash to cement mainly causes further retardation of hydration reactions due to the reactions of fly ash particles with Ca2+ ions from cement. The strongest effect on the hydration retardation from all investigated compounds showed in ZnO as it dissolves very slowly. On the contrary, for the dosage of 1% of zinc in the form of ZnCl2 significant acceleration of hydration occurred. In this work, a synergistic effect on the prolongation of hydration with a combination of cement, zinc and fly ash was demonstrated. The lengths of induction periods were assessed from detected calorimetric curves and from these lengths the curves were gained by fitting with the exponential function. Final products were next analyzed using X-ray diffraction., Zvyšující se míra využití druhotných surovin a alternativních paliv vede ke zvýšení obsahu kovů v cementech. Zinek je jedním z těchto prvků. Zinek následně přechází do cementu a druhotných surovinami, jako je struska nebo popílek. Zinek také přechází díky využití použitých pneumatik jako alternativního paliva. Ionty zinku významně prodlužují proces hydratace v cementu. Tato práce se zabývá vlivem iontů zinku ve formě velmi špatně rozpustné soli ZnO a snadno rozpustných ZnCl2 a Zn (NO3)2 na hydrataci cementu smíchaného s popílkem. Zinek byl dávkován v rozmezí 0,05%, 0,1%, 0,5% a 1% hmotnosti cementu. Vliv zinku na hydrataci byl sledován izotermickou a izoperibolickou kalorimetrií. 15% přidání popílku do cementu způsobí hlavně další zpomalení hydratačních reakcí v důsledku reakcí částic popílku s ionty Ca2+ z cementu. Nejsilnější účinek na zpomalení hydratace ze všech zkoumaných sloučenin se ukázal v ZnO, protože se rozpouští velmi pomalu. Naopak u dávky 1% zinku ve formě ZnCl2 došlo k významnému zrychlení hydratace. V této práci byl prokázán synergický účinek na prodloužení hydratace kombinací cementu, zinku a popílku. Délky indukčních period byly hodnoceny z detekovaných kalorimetrických křivek a z těchto délek byly křivky získány příslušné exponenciální funkei. Konečné produkty byly dále analyzovány pomocí rentgenové difrakce.