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.

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.

Experimental Study on Desulfurized Gypsum Modified Magnesium Oxychloride Cement

2011 ◽  
Vol 236-238 ◽  
pp. 1554-1558
Author(s):  
Zhi Jie Zhang ◽  
Tao Li ◽  
Ping An Liu
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Abrasion Loss ◽  
Magnesium Oxychloride ◽  
Abrasive Tools ◽  
Magnesium Oxychloride Cement ◽  
Softening Coefficient ◽  
Oxychloride Cement

The influences of desulfurization gypsum on the properties of both Magnesium oxychloride cement (MOC) pastes and MOC abrasive tools were investigated in this study. By incorporating desulfurization gypsum in the MOC pastes, the compressive strength of MOC paste improved slightly. With 5% gypsum addition, the flexural strength of MOC pastes increased by 36%, the abrasion loss of MOC abrasive tools decreased by 35%, the strength softening coefficient greatly increased. The mechanism maybe due to the microstructure of the MOC pastes became more compact with gypsum adding, the rate of hydrolyzation reaction of MOC phases would be postponed.

Influence of Calcium Added Slag on the Strength and Water-Repellency of Magnesium Oxychloride Cement

2013 ◽  
Vol 278-280 ◽  
pp. 437-439
Author(s):  
Yu Jie Jin ◽  
Li Guang Xiao ◽  
Feng Luo
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Water Repellency ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Softening Coefficient ◽  
Oxychloride Cement

The influence of dosage of calcium added slag on the strength and water-repellency of Magnesium oxychloride cement was studied in this paper. The results indicated that the compressive strength of magnesium oxychloride cement enhanced while the flexural strength remained unchanged when the dosage of calcium added slag between 5%-30%. The compressive strength of magnesium oxychloride cement was 110.0 MPa when the dosage of Calcium added slag was 20%, which increased the strength of 17%. The calcium added slag significantly improved the water-repellency of Magnesium oxychloride cement. The softening coefficient of magnesium oxychloride cement was more than 0.82, and the highest is 1.07.

Magnesium Oxychloride Cement Concrete with Recycled Tire Rubber

1996 ◽  
Vol 1561 (1) ◽  
pp. 6-12 ◽  
Author(s):  
Timothy D. Biel ◽  
Hosin Lee
Keyword(s):  
Tensile Strength ◽  
Portland Cement ◽  
Shear Failure ◽  
Portland Cement Concrete ◽  
Cement Concrete ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Rubber Concrete ◽  
Concrete Matrix ◽  
Oxychloride Cement

Either portland cement or magnesium oxychloride cement was used as binders for concretes that incorporated fine rubber aggregate, ranging from 0 to 25 percent by volume. The concretes were tested for their compressive and split tensile strengths to determine whether the use of a magnesium oxychloride cement along with recycled tire rubbers would improve concrete properties. Failure of the concrete around the rubber particles was attributed to tension failure, leading to weak shear failure of the concrete matrix. Both portland and magnesium oxychloride cement concretes lost 90 percent of their compressive strength with 25 percent rubber by volume. The portland cement concrete retained 20 percent of its tensile strength, and the magnesium oxychloride cement concrete retained 35 percent of its tensile strength. Both compressive and tensile strengths of magnesium oxychloride cement rubber concrete were significantly higher than rubberized portland cement rubber concrete.

Improved Magnesium Cement for Durable Hemp Composite Boards

2022 ◽  
Author(s):  
Jelizaveta Zorica ◽  
Maris Sinka ◽  
Genadijs Sahmenko ◽  
Diana Bajare
Keyword(s):  
Compressive Strength ◽  
Water Resistance ◽  
Chemical Reactivity ◽  
Ease Of Use ◽  
Lower Amount ◽  
Insulation Material ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Cement Board ◽  
Oxychloride Cement

Hemp concrete is a well-known bio-based building material, but due to its relatively low compressive strength is mainly used as an insulation material with a load-bearing wooden frame. There are possibilities to expand hemp concrete application in construction by substituting traditional lime with magnesium cement. Magnesium oxychloride cement is a material already known for some time and nowadays used in building board production. Strength, lightweight, ease of use are advantages that highlight relatively new magnesium oxychloride type boards compared to traditional sheeting materials such as plywood, gypsum plasterboard and fibre-cement board. Therefore, similar parameters are thought to be reached by producing magnesium oxychloride hemp board. In this work, magnesium cement water resistance was studied and possibilities to improve it was examined by adding fly ash and nanosilica. Among the nanomaterials used in building materials, nanosilica has gained significant interest by performing a beneficial effect in improving the mechanical properties of concretes. In addition, due to its ultrafine size and high chemical reactivity, the performance of nanosilica is much better with a lower amount of admixture required. Results show that applied nanosilica slightly reduced the compressive strength of magnesium cement in a dry state, but at the same time significantly increased its water resistance. Hemp magnesium oxychloride cement board prototype samples were produced and demonstrate promising results for further manufacturing of hemp composite boards.

Compressive strength of fly ash magnesium oxychloride cement containing granite wastes

2013 ◽  
Vol 38 ◽  
pp. 1-7 ◽  
Author(s):  
Ying Li ◽  
Hongfa Yu ◽  
Lina Zheng ◽  
Jing Wen ◽  
Chengyou Wu ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Magnesium Oxychloride ◽  
Magnesium Oxychloride Cement ◽  
Oxychloride Cement
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