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15. Graphene- and Graphite Oxide-Reinforced Magnesium Oxychloride Cement Composites for the Construction Use

Author

Lauermannová, Anna-Marie, Lojka, Michal, Pavlíková, Milena, Pivák, Adam, Záleská, Martina, Pavlík, Zbyšek, Zmeškal, Oldřich, and Jankovský, Ondřej

Subjects
Materials science, General Chemical Engineering, water, chemistry.chemical_element, Graphite oxide, reduction, Analytical Chemistry, law.invention, chemistry.chemical_compound, silica Fume, law, Materials Chemistry, Physical and Theoretical Chemistry, Composite material, phase, Composites, doped Graphene, Graphene, Magnesium, Cement composites, Magnesium oxychlorides, chemistry, Multiwalled Carbon Nanotubes, adsorption, Ceramics and Composites, metal-Ionsmechanical-Properties, hydration
Abstract

Graphene and graphite oxide reinforced magnesium oxychloride cement (MOC) pastes were researched. To produce MOC pastes, the light-burnt magnesium oxide was added and dispersed in the magnesium chloride solution. The graphene powder, graphite oxide powder, and their combination were incorporated in the solution. The total amount of the nano additives was 0.5 % by the weight of the magnesium oxychloride binder. The morphology and microstructure of the hardened materials were studied using scanning electron microscopy (SEM). The phase composition of precipitated MOC-based products was investigated using X ray diffraction (XRD). The macrostructural parameters of the composites such as bulk density, specific density, and open porosity were evaluated. Mechanical strength and stiffness were analyzed by the measurement of flexural and compressive strength and dynamic elastic modulus. The electrical properties were examined by the use of impedance spectroscopy (IS). From the experimental results the model of the transport of electric charge in researched materials dispersion was estimated. The use of graphene- and graphite oxide-reinforcement of MOC matrix gave highly dense materials of low porosity, high mechanical resistance, whereas the used nano-additives enabled the produce of composites of high strength efficiency index. The addition of graphene particles and the formation of graphite agglomerates significantly decreased electrical resistivity of the MOC matrix which was originally characterized by low electrical conductivity.

Published
2021

22. Hydrotalcites in Construction Materials

Author

Lauermannová, Anna-Marie, primary, Paterová, Iva, additional, Patera, Jan, additional, Skrbek, Kryštof, additional, Jankovský, Ondřej, additional, and Bartůněk, Vilém, additional

Published
2020
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24. Carbon Dioxide Uptake by MOC-Based Materials

Author

Jankovský, Ondřej, primary, Lojka, Michal, additional, Lauermannová, Anna-Marie, additional, Antončík, Filip, additional, Pavlíková, Milena, additional, Pavlík, Zbyšek, additional, and Sedmidubský, David, additional

Published
2020
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27. Magnesium Oxybromides MOB-318 and MOB-518: Brominated Analogues of Magnesium Oxychlorides.

Author

Lauermannová, Anna-Marie, Lojka, Michal, Antončík, Filip, Sedmidubský, David, Pavlíková, Milena, Pavlík, Zbyšek, and Jankovský, Ondřej

Subjects
SUSTAINABLE buildings, SCANNING transmission electron microscopy, MAGNESIUM, FOURIER transform infrared spectroscopy, ENERGY dispersive X-ray spectroscopy, CONSTRUCTION materials, FIRE resistant polymers, TRANSLUCENCY (Optics)
Abstract

Featured Application: The data acquired from the conducted tests and analyses can be used in the design and development of energy-efficient low-carbon construction materials. Because magnesium oxybromide phases (MOB-318, MOB-518) are stable, non-defective and well densified, high mechanical resistance of MOB-based materials can be anticipated similarly to magnesium oxychloride cement (MOC). Analogous to MOC, precipitated MOB phases can accommodate a great volume of inorganic and organic fillers and aggregates, which enables the production of alternative construction materials for specific applications. MOB-based materials can thus meet specific technical, functional and performance criteria of building practice. As MOB-318 can transmit light, it can be used in the design of a novel, highly optically-transparent material for light-transmitting decorative panels, partition walls, facing panels, translucent bricks and other architectural elements. Another specific attribute of MOB is its marble-like appearance, which makes it suitable as a decorative material. MOB-based composites can also serve as flame retardants. As such, they can potentially find use in the form of insulation boards or ceiling slabs to ensure the fire safety of steel structure buildings. The search for environmentally sustainable building materials is currently experiencing significant expansion. It is increasingly important to find new materials or reintroduce those that have been set aside to find a good replacement for Portland cement, which is widely used despite being environmentally insufficient and energy-intensive. Magnesium oxybromides, analogues to well-known magnesium oxychloride cements, fit both categories of new and reintroduced materials. In this contribution, two magnesium oxybromide phases were prepared and thoroughly analyzed. The stoichiometries of the prepared phases were 5Mg(OH)2∙MgBr2∙8H2O and 3Mg(OH)2∙MgBr2∙8H2O. The phase analysis was determined using X-ray diffraction. The morphology was analyzed with scanning and transmission electron microscopy. The chemical composition was studied using X-ray fluorescence and energy dispersive spectroscopy. Fourier transform infrared spectroscopy was also used. The thermal stability and the mechanism of the release of gasses linked to the heating process, such as water and hydrobromic acid evaporation, were analyzed using simultaneous thermal analysis combined with mass spectroscopy. The obtained results were compared with the data available for magnesium oxychlorides. [ABSTRACT FROM AUTHOR]

Published
2020
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