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

Flame Retardant Coatings: Additives, Binders, and Fillers

This review provides an intensive overview of flame retardant coating systems. The occurrence of flame due to thermal degradation of the polymer substrate as a result of overheating is one of the major concerns. Hence, coating is the best solution to this problem as it prevents the substrate from igniting the flame. In this review, the descriptions of several classifications of coating and their relation to thermal degradation and flammability were discussed. The details of flame retardants and flame retardant coatings in terms of principles, types, mechanisms, and properties were explained as well. This overview imparted the importance of intumescent flame retardant coatings in preventing the spread of flame via the formation of a multicellular charred layer. Thus, the intended intumescence can reduce the risk of flame from inherently flammable materials used to maintain a high standard of living.

The Effect of Doping High Volume Magnesium Sulfate on Properties of Magnesium Oxychloride Cement

The composite gelling system of chlorine and magnesium thioxide was prepared by mixing different mass fractions of magnesium sulfate solution into MOC. Detailed studies regarding the influences of magnesium sulfate replacing magnesium chloride on the setting time, compressive strength, and water resistance of magnesium oxychloride cement (MOC) have been carried out in this paper. The phase composition and micro morphology of the hydration products in the mixed system were analyzed by XRD and SEM. The results show that the addition of magnesium sulfate prolongs the setting time and reduces the compressive strength of the mixed MOC. Compared with the primordial MOC system, the water resistance of the mixed system improved, with the mixed system exhibiting optimal water resistance when the mass fraction of magnesium sulfate was 30%. The phases of the mixed system were composed of 5Mg(OH)2·MgCl2·8H2O and 5Mg(OH)2·MgSO4·7H2O phases. The microscopic morphology shows that the interior of air-cured MOC was composed of a large number of needle-like crystals, and continuous crystal structures have close contact and a strong bonding force. Cracks and pores appear on the surface after submerging in water, and the crystallization state of the internal crystals becomes worse. The compressive strength and water stability of MOC were closely related to the crystal morphology.

Perspective of Using Magnesium Oxychloride Cement (MOC) and Wood as a Composite Building Material: A Bibliometric Literature Review

The building industry is known as one of the biggest consumers of natural resources and an important producer of CO₂ emissions. The biggest greenhouse gas emissions are recorded in the production of cement and metallic building materials. The purpose of this paper is to investigate if magnesium oxychloride cement (MOC) can be used as an alternative to the ordinary Portland cement in the mixture of wood–cement composite building materials in order to decrease the negative impact of the construction industry on the environment. The research methodology includes bibliometric literature research, a scientometric analysis and an in-depth discussion. The data used for the research were obtained by interrogating the ISI Web of Science database, selected using the guidelines of the PRISMA method and processed with the help of VOSviewer and Bibliometrix software. The research results indicate an increasing interest in this topic; for example, in the last five years, three times more articles were published on the subject of MOC cement than the number of all articles collected in previous years. Compared to ordinary Portland cement, MOC cement presents a good match with wood, so MOC can be a substitute for ordinary cement to manufacture wood-cement particleboard, especially for the wood species that have high incompatibility with ordinary cement.

Co-Doped Magnesium Oxychloride Composites with Unique Flexural Strength for Construction Use

In this study, the combined effect of graphene oxide (GO) and oxidized multi-walled carbon nanotubes (OMWCNTs) on material properties of the magnesium oxychloride (MOC) phase 5 was analyzed. The selected carbon-based nanoadditives were used in small content in order to obtain higher values of mechanical parameters and higher water resistance while maintaining acceptable price of the final composites. Two sets of samples containing either 0.1 wt. % or 0.2 wt. % of both nanoadditives were prepared, in addition to a set of reference samples without additives. Samples were characterized by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and energy dispersive spectroscopy, which were used to obtain the basic information on the phase and chemical composition, as well as the microstructure and morphology. Basic macro- and micro-structural parameters were studied in order to determine the effect of the nanoadditives on the open porosity, bulk and specific density. In addition, the mechanical, hygric and thermal parameters of the prepared nano-doped composites were acquired and compared to the reference sample. An enhancement of all the mentioned types of parameters was observed. This can be assigned to the drop in porosity when GO and OMWCNTs were used. This research shows a pathway of increasing the water resistance of MOC-based composites, which is an important step in the development of the new generation of construction materials.

MOC Doped with Graphene Nanoplatelets: The Influence of the Mixture Preparation Technology on Its Properties

The ongoing tendency to create environmentally friendly building materials is nowadays connected with the use of reactive magnesia-based composites. The aim of the presented research was to develop an ecologically sustainable composite material based on MOC (magnesium oxychloride cement) with excellent mechanical, chemical, and physical properties. The effect of the preparation procedure of MOC pastes doped with graphene nanoplatelets on their fresh and hardened properties was researched. One-step and two-step homogenization techniques were proposed as prospective tools for the production of MOC-based composites of advanced parameters. The conducted experiments and analyses covered X-ray fluorescence, scanning electron microscopy, energy-dispersive spectroscopy, high-resolution transmission electron microscopy, sorption analysis, X-ray diffraction, and optical microscopy. The viscosity of the fresh mixtures was monitored using a rotational viscometer. For the hardened composites, macro- and micro-structural parameters were measured together with the mechanical parameters. These tests were performed after 7 days and 14 days. The use of a carbon-based nanoadditive led to a significant drop in porosity, thus densifying the MOC matrix. Accordingly, the mechanical resistance was greatly improved by graphene nanoplatelets. The two-step homogenization procedure positively affected all researched functional parameters of the developed composites (e.g., the compressive strength increase of approximately 54% after 7 days, and 37% after 14 days, respectively) and can be recommended for the preparation of advanced functional materials reinforced with graphene.

Foam Glass Lightened Sorel's Cement Composites Doped with Coal Fly Ash

Lightweight Sorel’s cement composites doped with coal fly ash were produced and tested. Commercially available foam granulate was used as lightening aggregate. For comparison, reference composites made of magnesium oxychloride cement (MOC) and quartz sand were tested as well. The performed experiments included X-ray diffraction, X-ray fluorescence, scanning electron microscopy, light microscopy, and energy dispersive spectroscopy analyses. The macro- and microstructural parameters, mechanical resistance, stiffness, hygric, and thermal parameters of the 28-days matured composites were also researched. The combined use of foam glass and fly ash enabled to get a material of low weight, high porosity, sufficient strength and stiffness, low water imbibition, and greatly improved thermal insulation performance. The developed lightweight composites can be considered as further step in the design and production of alternative and sustainable materials for construction industry.

Water-to-Cement Ratio of Magnesium Oxychloride Cement Foam Concrete with Caustic Dolomite Powder

Magnesium oxychloride cement (MOC) foam concrete (MOCFC) is an air-hardening cementing material formed by mixing magnesium chloride solution (MgCl2) and light-burned magnesia (i.e., active MgO). In application, adding caustic dolomite powder into light-burned magnesite powder can reduce the MOCFC production cost. The brine content of MOC changes with the incorporation of caustic dolomite powder. This study investigated the relationship between the mass percent concentration and the Baumé degree of a magnesium chloride solution after bischofite (MgCl2·6H2O) from a salt lake was dissolved in water. The proportional relationship between the amount of water in brine and bischofite, and the functional formula for the water-to-cement ratio (W/C) of MOC mixed with caustic dolomite powder were deduced. The functional relationship was verified as feasible for preparing MOC through the experiment.

Magnesium Oxychloride Cement Composites with MWCNT for the Construction Applications

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.

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

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.

Eco-Friendly Materials Obtained by Fly Ash Sulphuric Activation for Cadmium Ions Removal

Wastes are the sustainable sources of raw materials for the synthesis of new adsorbent materials. This study has as objectives the advanced capitalization of fly ash, by sulphuric acid activation methods, and testing of synthesized materials for heavy metals removal. Based on the previous studies, the synthesis parameters were 1/3 s/L ratio, 80 °C temperature and 10% diluted sulphuric acid, which permitted the synthesis of an eco-friendly adsorbent. The prepared adsorbent was characterized through SEM, EDX, FTIR, XRD and BET methods. Adsorption studies were carried out for the removal of Cd²⁺ ions, recognized as ions dangerous for the environment. The effects of adsorbent dose, contact time and metal ion concentrations were studied. The data were tested in terms of Langmuir and Freundlich isotherm and it was found that the Langmuir isotherm fitted the adsorption with a maximum adsorption capacity of 28.09 mg/g. Kinetic data were evaluated with the pseudo-first-order model, the pseudo-second-order model and the intraparticle diffusion model. The kinetics of cadmium adsorption into eco-friendly material was described with the pseudo-second-order model, which indicated the chemisorption mechanism.