scholarly journals The Impact of Graphene and Diatomite Admixtures on the Performance and Properties of High-Performance Magnesium Oxychloride Cement Composites

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5708
Author(s):  
Anna-Marie Lauermannová ◽  
Filip Antončík ◽  
Michal Lojka ◽  
Ondřej Jankovský ◽  
Milena Pavlíková ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Pore Size ◽  
High Performance ◽  
Graphene Nanoplatelets ◽  
Silica Sand ◽  
X Ray ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
The Impact ◽  
Oxychloride Cement

A high-performance magnesium oxychloride cement (MOC) composite composed of silica sand, diatomite powder, and doped with graphene nanoplatelets was prepared and characterized. Diatomite was used as a 10 vol.% replacement for silica sand. The dosage of graphene was 0.5 wt.% of the sum of the MgO and MgCl2·6H2O masses. The broad product characterization included high-resolution transmission electron microscopy, X-ray diffraction, X-ray fluorescence, scanning electron microscopy and energy dispersive spectroscopy analyses. The macrostructural parameters, pore size distribution, mechanical resistance, stiffness, hygric and thermal parameters of the composites matured for 28-days were also the subject of investigation. The combination of diatomite and graphene nanoplatelets greatly reduced the porosity and average pore size in comparison with the reference material composed of MOC and silica sand. In the developed composites, well stable and mechanically resistant phase 5 was the only precipitated compound. Therefore, the developed composite shows high compactness, strength, and low water imbibition which ensure high application potential of this novel type of material in the construction industry.

scholarly journals Magnesium Oxychloride Cement Composites Lightened with Granulated Scrap Tires and Expanded Glass

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4828 ◽  
Author(s):  
Milena Pavlíková ◽  
Adam Pivák ◽  
Martina Záleská ◽  
Ondřej Jankovský ◽  
Pavel Reiterman ◽  
...  
Keyword(s):  
Resistance Coefficient ◽  
Added Value ◽  
Silica Sand ◽  
Low Carbon ◽  
Magnesium Chloride Solution ◽  
Scrap Tires ◽  
Filling Materials ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Oxychloride Cement

In this paper, light burned magnesia dispersed in the magnesium chloride solution was used for the manufacturing of magnesium oxychloride cement-based composites which were lightened by granulated scrap tires and expanded glass. In a reference composite, silica sand was used only as filler. In the lightened materials, granulated shredded tires were used as 100%, 90%, 80%, and 70% silica sand volumetric replacement. The rest was compensated by the addition of expanded glass granules. The filling materials were characterized by particle size distribution, specific density, dry powder density, and thermal properties that were analyzed for both loose and compacted aggregates. For the hardened air-cured samples, macrostructural parameters, mechanical properties, and hygric and thermal parameters were investigated. Specific attention was paid to the penetration of water and water-damage, which were considered as crucial durability parameters. Therefore, the compressive strength of samples retained after immersion for 24 h in water was tested and the water resistance coefficient was assessed. The use of processed waste rubber and expanded glass granulate enabled the development of lightweight materials with sufficient mechanical strength and stiffness, low permeability for water, enhanced thermal insulation properties, and durability in contact with water. These properties make the produced composites an interesting alternative to Portland cement-based materials. Moreover, the use of low-carbon binder and waste tires can be considered as an eco-efficient added value of these products which could improve the environmental impact of the construction industry.

scholarly journals Synthesis, Structure, and Thermal Stability of Magnesium Oxychloride 5Mg(OH)2∙MgCl2∙8H2O

2020 ◽  
Vol 10 (5) ◽  
pp. 1683 ◽  
Author(s):  
Adéla Jiříčková ◽  
Michal Lojka ◽  
Anna-Marie Lauermannová ◽  
Filip Antončík ◽  
David Sedmidubský ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Compressive Strength ◽  
Portland Cement ◽  
Mass Spectroscopy ◽  
Carbon Footprint ◽  
X Ray ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Thermal Stability Of ◽  
Oxychloride Cement

Today, low-energy and low-carbon footprint alternatives to Portland cement are searched because of huge CO2 emissions coming from Portland clinker calcination. Because of some superior properties of magnesium oxychloride cement (MOC) and the lower carbon footprint of its production, MOC became an intensively studied material with high application potential for the design and development of construction products. In this contribution, magnesium oxychloride with stoichiometry 5Mg(OH)2∙MgCl2∙8H2O (Phase 5) was prepared and characterized. The kinetics of formation and the phase composition of the material were determined using X-ray diffraction and consequent Rietveld analysis. The morphology was studied by scanning electron microscopy, and the chemical composition was determined by both energy-dispersive spectroscopy and X-ray fluorescence. Moreover, the simultaneous thermal analysis in combination with mass spectroscopy and Fourier-transform infrared spectroscopy was employed to study the thermal stability. Using mass spectroscopy, we were able to clarify the mechanism of water and hydrochloric acid release, which was not previously reported. The observed structural and chemical changes induced by exposure of studied samples to elevated temperatures were linked with the measured residual macro and micro parameters, such as bulk density, specific density, porosity, water absorption, compressive strength, and pore size distribution. The Phase 5 revealed a needle-like crystalline morphology which formed rapidly and was almost completed after 96 h, resulting in relatively high material strength. The four-day compressive strength of magnesium oxychloride cement was similar to the 28-day compressive strength of Portland cement. The thermal stability of Phase 5 was low as the observed disruptive thermal processes were completed at temperatures lower than 470 °C.

Influence of MgCl2 Solution Concentration on Strength of Magnesium Oxychloride Cement Concrete

2012 ◽  
Vol 450-451 ◽  
pp. 791-795 ◽  
Author(s):  
Hong Xia Qiao ◽  
Yao Liu ◽  
Ming Ru Zhou ◽  
Hong Fa Yu ◽  
Jian Feng
Keyword(s):  
Solution Concentration ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Cement Concrete ◽  
X Ray ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Mgcl2 Solution ◽  
Scanning Electron ◽  
Oxychloride Cement

The molar ratio of MgO and MgCl2 affects prominently on the strength of Magnesium Oxychloride Cement Concrete. Different ratios were used to explore the optimum mixture proportion with the highest uniaxial compressive strength. The influence of the MgCl2 solution concentration is presented. XRD (X-ray diffraction) and SEM (scanning electron microscope) was used to analyze the micro-mechanism.

scholarly journals Effect of Calcination Temperature on Mechanical Properties of Magnesium Oxychloride Cement

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 607
Author(s):  
Chenggong Chang ◽  
Lingyun An ◽  
Rui Lin ◽  
Jing Wen ◽  
Jinmei Dong ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Calcination Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Scanning Electron ◽  
Oxychloride Cement

In order to make full use of magnesium chloride resources, the development and utilisation of magnesium oxychloride cement have become an ecological and economic goal. Thus far, however, investigations into the effects on these cements of high temperatures are lacking. Herein, magnesium oxychloride cement was calcinated at various temperatures and the effects of calcination temperature on microstructure, phase composition, flexural strength, and compressive strength were studied by scanning electron microscopy, X-ray diffraction, and compression testing. The mechanical properties varied strongly with calcination temperature. Before calcination, magnesium oxychloride cement has a needle-like micromorphology and includes Mg(OH)2 gel and a trace amount of gel water as well as 5 Mg(OH)2·MgCl2·8H2O, which together provide its mechanical properties (flexural strength, 18.4 MPa; compressive strength, and 113.3 MPa). After calcination at 100 °C, the gel water is volatilised and the flexural strength is decreased by 57.07% but there is no significant change in the compressive strength. Calcination at 400 °C results in the magnesium oxychloride cement becoming fibrous and mainly consisting of Mg(OH)2 gel, which helps to maintain its high compressive strength (65.7 MPa). When the calcination temperature is 450 °C, the microstructure becomes powdery, the cement is mainly composed of MgO, and the flexural and compressive strengths are completely lost.

scholarly journals Magnesium Oxychloride Cement Composites with Silica Filler and Coal Fly Ash Admixture

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2537 ◽  
Author(s):  
Adam Pivák ◽  
Milena Pavlíková ◽  
Martina Záleská ◽  
Michal Lojka ◽  
Ondřej Jankovský ◽  
...  
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Coal Fly Ash ◽  
Cement Industry ◽  
Silica Sand ◽  
Great Decrease ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
And Storage ◽  
Oxychloride Cement

Worldwide, Portland cement-based materials are the most commonly used construction materials. As the Portland cement industry negatively affects the environment due to the excessive emission of carbon dioxide and depletion of natural resources, new alternative materials are being searched. Therefore, the goal of the paper was to design and develop eco-friendly, low-cost, and sustainable magnesium oxychloride cement (MOC)-based building material with a low carbon footprint, which is characterized by reduced porosity, high mechanical resistance, and durability in terms of water damage. To make new material eco-efficient and functional, silica sand which was used in the composition of the control composite mixture was partially replaced with coal fly ash (FA), a byproduct of coal combustion. The chemical and mineralogical composition, morphology, and particle morphology of FA were characterized. For silica sand, FA, and MgO, specific density, loose bulk density, and particle size distribution were measured. Additionally, Blaine specific surface was for FA and MgO powder assessed. The workability of fresh mixtures was characterized by spread diameter. For the hardened MOC composites, basic structural, mechanical, hygric, and thermal properties were measured. Moreover, the phase composition of precipitated MOC phases and their thermal stability were investigated for MOC-FA pastes. The use of FA led to the great decrease in porosity and pore size compared to the control material with silica sand as only filler which was in agreement with the workability of fresh composite mixtures. The compressive strength increased with the replacement of silica sand with FA. On the contrary, the flexural strength slightly decreased with silica sand substitution ratio. It clearly proved the assumption of the filler function of FA, whereas its assumed reactivity with MOC cement components was not proven. The water transport and storage were significantly reduced by the use of FA in composites, which greatly improved their resistance against moisture damage. The heat transport and storage parameters were only slightly affected by FA incorporation in composite mixtures.

Study on Recycle of Sawdust Sorel’s Cement Concrete Waste

2010 ◽  
Vol 113-116 ◽  
pp. 382-385
Author(s):  
Cheng Dong Li ◽  
Hong Fa Yu
Keyword(s):  
High Temperature ◽  
X Ray Diffraction ◽  
Cement Concrete ◽  
X Ray ◽  
Temperature Conditions ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Great Harm ◽  
Oxychloride Cement

Magnesium oxychloride cement sawdust concrete box caused great harm to the environment. This article introduced the method to recycle the box. Magnesium oxychloride cement sawdust concrete was gradually heated, in the range of 0 ~ 800°C, and then the residue was calcined at 700 ° C. Studies showed that the 5•1•8 and sawdust in the box was decomposed into MgO in high temperature conditions. The X-ray diffraction examination results showed that the content of this MgO reached 90%. The application the MgO is very wide.

scholarly journals Magnesium Oxychloride Cement Composites with MWCNT for the Construction Applications

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 484
Author(s):  
Michal Lojka ◽  
Anna-Marie Lauermannová ◽  
David Sedmidubský ◽  
Milena Pavlíková ◽  
Martina Záleská ◽  
...  
Keyword(s):  
Structural Parameters ◽  
Mechanical Resistance ◽  
Cement Composites ◽  
Multi Walled Carbon Nanotubes ◽  
The Subject ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Phase And Chemical Composition ◽  
Walled Carbon Nanotubes ◽  
Oxychloride Cement

In this contribution, composite materials based on magnesium oxychloride cement (MOC) with multi-walled carbon nanotubes (MWCNTs) used as an additive were prepared and characterized. The prepared composites contained 0.5 and 1 wt.% of MWCNTs, and these samples were compared with the pure MOC Phase 5 reference. The composites were characterized using a broad spectrum of analytical methods to determine the phase and chemical composition, morphology, and thermal behavior. In addition, the basic structural parameters, pore size distribution, mechanical strength, stiffness, and hygrothermal performance of the composites, aged 14 days, were also the subject of investigation. The MWCNT-doped composites showed high compactness, increased mechanical resistance, stiffness, and water resistance, which is crucial for their application in the construction industry and their future use in the design and development of alternative building products.

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