AdMaS MSH - Technologie hmot a dílců

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    Effect of wood chips properties on mineralogical composition and microstructure of silicate matrix based composites
    (IOP Publishing, 2018-07-16) Melichar, Tomáš; Bydžovský, Jiří; Dufka, Amos
    The research presented in this article was focused on proving the effect of wood chips parameters on the hardening process of silicate matrix in cement-bonded particleboard. Namely content of humidity in the chips (in range 30 to 90%) was significant. This amount of humidity was chosen with respect to real conditions of cement-bonded particleboards production. Influence of humidity could be reflected in the content of sugar (cellulose etc.) in wooden chips. The sugars affect the hardening of matrix negatively. Thus, phase composition and microstructure of matrix of cement-bonded particle boards were analysed during 2 to 28 days. Investigation of physico-chemical parameters and microstructure was also supplemented by verification of the basic material characteristics of cement-bonded particleboards (strength and modulus of elasticity in bending, transverse tensile strength perpendicular to the plane of the board, etc.).
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    The influence of the addition of gypsum on some selected properties of lime-metakaolin mortars
    (IOP Publishing, 2018-07-16) Majerová, Jana; Drochytka, Rostislav
    The renovation and replacement of historical plasters is still a very current topic. Today’s trend is for the production of dry mortar mixtures that can be used for the renovation of historic buildings. The article therefore focuses on the preparation of gypsum-modified lime-metakaolin mortar. An experiment consisted of two stages. In the first stage of the experiment, the basic technological properties of fresh and hardened mortars were examined (bulk density of fresh and hardener mortar, compressive and flexural strength). The second stage aimed at monitoring the hydration process in different environments. Environments should simulate real factors affecting the plaster (humidity, low and higher temperatures). To determinate of the phase composition, the X-ray diffraction analysis was used. The results showed that gypsum in the lime-metakaolin plaster caused an increase in compressive and flexural strength. The presence of gypsum also conduced to the formation of ettringite and this has caused volumetric changes.
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    The evaluation of the effect of crystallization additives on long term durability of self-compacting concrete
    (IOP Publishing, 2018-07-16) Dufka, Amos; Melichar, Tomáš
    The article deals with the influence of crystallisation additives on the life of self-compacting concrete (so-called SCC concrete) in case of exposure to aggressive gases. The effect of crystallization additives on the properties of such modified composites is generally tested during exposure of liquid media, in this case the attention is focused on influence of selected types of aggressive gases (CO2 and SO2). The impact of individual types of aggressive gases is assessed on the basis of a set of physico-mechanical and physico-chemical analyses.
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    Fracture Mechanism of Interpenetrating Iron-Tricalcium Phosphate Composite
    (Trans Tech Publications, 2017-01-01) Horynová, Miroslava; Casas Luna, Mariano; Montufar Jimenez, Edgar Benjamin; Díaz de la Torre, Sebastian; Čelko, Ladislav; Klakurková, Lenka; Diéguez-Trejo, Guillermo; Dvořák, Karel; Zikmund, Tomáš; Kaiser, Jozef
    The usage of iron alloys for bone fractures treatment has been limited due to its high density and elastic modulus, as compared to bone. In contrast, the use of tricalcium phosphate (TCP), a ceramic that promotes bone healing, is mostly limited by its brittle nature. In the present work the fracture mechanism of a novel iron-TCP interpenetrated composite fabricated by spark plasma sintering was studied. Specimens were subjected to a diametral tensile-strength-test. The work of fracture was determined by indirect tensile loading conditions using the diametral tensile strength test. The results revealed that iron has a clear toughening effect on the microstructure of tricalcium phosphate specimens consolidated by spark plasma sintering. This is a promising result to overcome the limited usage of tricalcium phosphate to treat only non-load bearing bone defects.