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    Mortars with crystalline additive in aggressive environments
    (IOP Publishing, 2018-07-16) Žižková, Nikol; Nevřivová, Lenka; Lédl, Matěj; Keprdová, Šárka
    The paper describes how a crystalline additive influences the properties of cementbased composites. The investigation was focused on the degradation of mortars with crystalline additive exposed to selected aggressive environments. The specimens were tested for compressive and flexural strength. The influence on the microstructure is also discussed (high pressure mercury intrusion porosimetry, SEM, DTA). The results confirmed the positive influence of a crystalline additive on the values of compressive strength after exposure to all aggressive environments.
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    The Effect of the Wear of Rotor Pins on Grinding Efficiency in a High-speed Disintegrator
    (Kaunas University of Technology, 2018-02-19) Dvořák, Karel; Dolák, Dušan; Paloušek, David; Čelko, Ladislav; Jech, David
    One of the directions intensively investigated in the field of milling is high-energy milling (HEM). One type of HEM is high-speed grinding in high-speed disintegrators. This type of mill is particularly suitable for the grinding and activation of fine powder materials. It has several advantages, such as a very intensive and continual refining process. One disadvantage is that its grinding pins are prone to abrasion, which may result in a decrease of the efficiency of grinding. This effect was investigated in this paper.
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    Raw materials for mullite grog manufacturing
    (IOP Publishing, 2018-07-07) Nevřivová, Lenka
    The primary condition for manufacturing is the correct choice of raw material, a suitable treatment facility, and a kiln capable of firing at temperatures above 1400 °C. This paper assesses some local raw materials for grog manufacturing and compares the results with a mullite grog of similar properties that is available on the European market.
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    The FBC ash as a hydraulic ingredient of hydraulic lime
    (Elsevier, 2017-01-31) Dvořák, Karel; Kulísek, Karel; Gazdič, Dominik
    This work is focused on the possibilities of utilization of ashes from fluidized bed combustion, i.e. FBC ashes, for the manufacturing of hydraulic lime. Alternative hydraulic binders are becoming very popular in the present due to requirements on reducing CO2 emissions. FBC ash is an easily available, though not easily usable raw material. Because it has several hydraulic characteristics, it can create a hydraulic binder together with lime. Mixtures of hydrated lime and FBC ash from filters and from a bed were prepared in this work. The main criterion was the hydraulic modulus. The physico-mechanical properties were observed and were compared with the reference sample, which was hydraulic lime from industrial production. The prepared hydraulic limes achieved similar parameters as commercially manufactured hydraulic limes or lower strength class cements.
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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.