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    Utilization of by-products for vacuum insulation panels production
    (IOP Publishing, 2018-07-12) Zach, Jiří; Peterková, Jitka; Novák, Vítězslav
    The paper deals with the possibilities of utilization of alternative raw materials from the textile industry for the production of vacuum insulation panels with extremely low thermal conductivity value. The paper presents current research findings on the behavior of fibrous structures on an organic basis at extremely low pressure. In addition, the paper presents the practical findings and results of experimental work in the production area and the behavior of vacuum insulation panels with an alternative core insulator based on organic fibers.
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    Immobilization of Heavy Metals in Natural Zeolite-blended Cement Pastes
    (Elsevier, 2016-09-26) Vyšvařil, Martin; Bayer, Patrik
    This paper deals with the investigation of efficiency of natural zeolite-blended cement pastes for the immobilization of heavy metals. Natural zeolite was used to partially replace ordinary Portland cement (OPC) at rates of 0% and 20% by weight of a binder and soluble heavy metal salts were added to a mixing water in an amount of 1% and 5% by weight of the binder. The flexural and compressive strength of the cement pastes were investigated, while the leachability of the heavy metals was determined. Additionally, scanning electron microscopy was performed to investigate the microstructure of the cement pastes, while the pore size distribution was analyzed with mercury intrusion porosimetry. The results indicated that the flexural and compressive strengths of the pastes containing 20 wt.% of natural zeolite were higher than those with OPC alone. It was also found out that the effectiveness in reducing the leachability of Ba, Cd, Cu, Ni and Pb was better for the natural zeolite-blended cement pastes.
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    Development of Vacuum Insulation Panels with Utilization of Organic By-Products
    (MDPI, 2020-03-04) Zach, Jiří; Novák, Vítězslav; Peterková, Jitka; Bubeník, Jan
    The need for the development of new, advanced building materials increases every year, especially due to the necessary diminution of energy performance for building structures and for building production itself (including the production of building materials). Along with the energy performance problems in construction, the issue of CO2 emission associated with building and the production of building materials is also important. In the field of advanced thermal insulation materials, vacuum insulation panels (VIPs) give the best results. However, their high-energy performance and material consumption present a problem. This work represents an initial part of the development of alternative insulators, based on agricultural and textile industry waste usable in the production of VIP. This article recapitulates basic knowledge regarding key thermal insulation properties of developed insulators and their fire reactions, which impact possible usage in building structures
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    Carbon Nanotubes in Cementitious Composites: Dispersion, Implementation, and Influence on Mechanical Characteristics
    (Hindawi, 2016-06-14) Jarolím, Tomáš; Labaj, Martin; Hela, Rudolf; Michnová, Kamila
    In article were descibed possibilities of CNT's dipersion. Implementation CNT to the cements matrix and it's influence to the mechanical properties
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    Long-term Observation of Yeelimite Clinker Hydration in Environment of Saturated Water Vapour
    (Elsevier, 2016-08-03) Pekárková, Jana; Kulísek, Karel; Gazdič, Dominik; Fridrichová, Marcela
    Due to ecological overloading decrease, industrial by-products are utilized. Fly ash also belongs among these by-products. In Portland-composite cements, the high-temperature fly ash is applied nowadays, but fluidized bed combustion fly ash (FBC fly ash) is not used. The reason is that the FBC fly ash hydrates to form an undesirable ettringite, C3A.3CaSO4.32H2O. Decomposition temperature of ettringite in ambient conditions is most often mentioned in a range of 50 °C to 110 °C. In order to assess the ettringite long-term stability, ettringite was synthesized by hydration of mineral yeelimite, 3CaO.3Al2O3.CaSO4. The aim of this paper is long-term observation of the hydration of yeelimite in environment of saturated water vapour and examination of how stable the products of hydration are under given conditions. Raw materials for preparation of yeelimite were gypsum, limestone and corundum, weighed according to stoichiometric ratio of yeelimite. The mixture was heated at temperature of 1200 °C, soak 3 hours. After quenching and grinding, yeelimite was hydrated with a water-yeelimite ratio of 0.3. The system was cured as pastes and stored in conditions at laboratory temperature and in settings of saturated water vapour (100% R.H.). In order to follow the progress of synthesis regularly, namely up to age of 180 days of hydration, X-ray diffraction (XRD) was chosen using diffractometer Empyrean PANalytical (CuK-alpha). Based on the XRD patterns, only minor part of ettringite was formed, whilst a majority of yeelimite was preserved. It has been found that ettringite was not the only one product of yeelimite hydration. From an age of 20 days of hydration, a small amount of monosulfate was identified, whose quantity rose gradually. Especially at later ages of hydration, transformation of ettringite into monosulfate was observed.